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@@ -0,0 +1,1083 @@
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+{
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+ "cells": [
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+ {
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+ "cell_type": "code",
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+ "execution_count": 1,
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+ "metadata": {},
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+ "outputs": [
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+ {
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+ "data": {
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+ "text/plain": [
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+ "array([37.2, 37.6, 36.8])"
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+ ]
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+ },
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+ "execution_count": 1,
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+ "metadata": {},
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+ "output_type": "execute_result"
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+ }
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+ ],
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+ "source": [
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+ "import numpy as np\n",
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+ "\n",
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+ "X = np.array([[1.2, 1.5, 1.8],\n",
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+ " [1.3, 1.4, 1.9],\n",
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+ " [1.1, 1.6, 1.7]])\n",
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+ "y = np.array([5, 10, 9]).T\n",
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+ "\n",
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+ "\n",
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+ "\n",
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+ "\n",
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+ "\n",
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+ "X.dot(y)\n",
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+ "\n"
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+ ]
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+ },
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+ {
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+ "cell_type": "code",
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+ "execution_count": 2,
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+ "metadata": {},
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+ "outputs": [
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+ {
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+ "data": {
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+ "text/plain": [
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+ "array([ 5, 10, 9])"
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+ ]
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+ },
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+ "execution_count": 2,
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+ "metadata": {},
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+ "output_type": "execute_result"
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+ }
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+ ],
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+ "source": [
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+ "y"
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+ ]
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+ },
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+ {
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+ "cell_type": "code",
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+ "execution_count": 4,
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+ "metadata": {},
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+ "outputs": [
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+ {
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+ "data": {
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+ "text/plain": [
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+ "(3, 3)"
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+ ]
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+ },
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+ "execution_count": 4,
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+ "metadata": {},
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+ "output_type": "execute_result"
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+ }
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+ ],
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+ "source": [
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+ "X.shape"
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+ ]
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+ },
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+ {
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+ "cell_type": "code",
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+ "execution_count": 3,
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+ "metadata": {},
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+ "outputs": [
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+ {
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+ "name": "stdout",
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+ "output_type": "stream",
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+ "text": [
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+ "1.04 µs ± 64.3 ns per loop (mean ± std. dev. of 7 runs, 1,000,000 loops each)\n"
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+ ]
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+ }
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+ ],
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+ "source": [
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+ "%timeit X.dot(y)"
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+ ]
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+ },
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+ {
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+ "cell_type": "code",
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+ "execution_count": 5,
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+ "metadata": {},
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+ "outputs": [
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+ {
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+ "name": "stdout",
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+ "output_type": "stream",
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+ "text": [
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+ "20.1 µs ± 589 ns per loop (mean ± std. dev. of 7 runs, 100,000 loops each)\n"
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+ ]
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+ }
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+ ],
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+ "source": [
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+ "%%timeit\n",
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+ "total = []\n",
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+ "for i in range(X.shape[0]):\n",
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+ " each_price = 0\n",
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+ " for j in range(X.shape[1]):\n",
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+ " each_price += X[i,j] * y[j]\n",
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+ "# each_price = each_price + X[i,j] * y[j]\n",
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+ " total.append(round(each_price, 1))\n",
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+ "total "
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+ ]
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+ },
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+ {
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+ "cell_type": "markdown",
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+ "metadata": {},
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+ "source": [
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+ "## 第二题"
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+ ]
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+ },
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+ {
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+ "cell_type": "code",
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+ "execution_count": 6,
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+ "metadata": {},
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+ "outputs": [
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+ {
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+ "data": {
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+ "text/plain": [
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+ "array([6, 9, 6, 1, 1, 2, 8, 7, 3, 5, 6, 3, 5, 3, 5, 8, 8, 2, 8, 1, 7, 8,\n",
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+ " 7, 2, 1, 2, 9, 9, 4, 9])"
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+ ]
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+ },
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+ "execution_count": 6,
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+ "metadata": {},
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+ "output_type": "execute_result"
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+ }
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+ ],
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+ "source": [
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+ "np.random.seed(1)\n",
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+ "X = np.random.randint(1, 10, size=30)\n",
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+ "X"
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+ ]
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+ },
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+ {
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+ "cell_type": "code",
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+ "execution_count": 12,
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+ "metadata": {},
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+ "outputs": [
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+ {
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+ "data": {
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+ "text/plain": [
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+ "array([[6, 9, 6],\n",
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+ " [1, 1, 2],\n",
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+ " [8, 7, 3],\n",
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+ " [5, 6, 3],\n",
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+ " [5, 3, 5],\n",
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+ " [8, 8, 2],\n",
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+ " [8, 1, 7],\n",
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+ " [8, 7, 2],\n",
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+ " [1, 2, 9],\n",
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+ " [9, 4, 9]])"
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+ ]
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+ },
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+ "execution_count": 12,
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+ "metadata": {},
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+ "output_type": "execute_result"
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+ }
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+ ],
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+ "source": [
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+ "X.reshape(-1,3)"
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+ ]
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+ },
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+ {
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+ "cell_type": "code",
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+ "execution_count": 14,
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+ "metadata": {},
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+ "outputs": [
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+ {
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+ "data": {
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+ "text/plain": [
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+ "array([[6, 9, 6],\n",
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+ " [1, 1, 2],\n",
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+ " [8, 7, 3],\n",
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+ " [5, 6, 3],\n",
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+ " [5, 3, 5],\n",
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+ " [8, 8, 2],\n",
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+ " [8, 1, 7],\n",
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+ " [8, 7, 2],\n",
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+ " [1, 2, 9],\n",
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+ " [9, 4, 9]])"
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+ ]
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+ },
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+ "execution_count": 14,
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+ "metadata": {},
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+ "output_type": "execute_result"
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+ }
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+ ],
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+ "source": [
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+ "X1 = X.reshape(-1 ,3)\n",
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+ "X1"
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+ ]
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+ },
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+ {
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+ "cell_type": "code",
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+ "execution_count": 16,
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+ "metadata": {},
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+ "outputs": [
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+ {
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+ "data": {
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+ "text/plain": [
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+ "array([6, 2, 3, 3, 5, 2, 7, 2, 9, 9])"
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+ ]
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+ },
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+ "execution_count": 16,
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+ "metadata": {},
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+ "output_type": "execute_result"
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+ }
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+ ],
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+ "source": [
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+ "last1 = X1[:, 2]\n",
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+ "last1"
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+ ]
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+ },
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+ {
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+ "cell_type": "code",
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+ "execution_count": 17,
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+ "metadata": {},
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+ "outputs": [
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+ {
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+ "data": {
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+ "text/plain": [
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+ "array([False, True, True, True, False, True, False, True, False,\n",
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+ " False])"
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+ ]
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+ },
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+ "execution_count": 17,
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+ "metadata": {},
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+ "output_type": "execute_result"
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+ }
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+ ],
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+ "source": [
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+ "last1 <= 3"
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+ ]
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+ },
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+ {
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+ "cell_type": "code",
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+ "execution_count": 18,
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+ "metadata": {},
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+ "outputs": [
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+ {
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+ "data": {
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+ "text/plain": [
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+ "array([2, 3, 3, 2, 2])"
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+ ]
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+ },
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+ "execution_count": 18,
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+ "metadata": {},
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+ "output_type": "execute_result"
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+ }
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+ ],
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+ "source": [
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+ "# 返回符合条件的位置,位置以True False来表示\n",
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+ "temp1 = last1[last1 <= 3]\n",
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+ "temp1"
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+ ]
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+ },
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+ {
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+ "cell_type": "code",
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+ "execution_count": 24,
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+ "metadata": {},
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+ "outputs": [
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+ {
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+ "data": {
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+ "text/plain": [
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+ "(array([1, 2, 3, 5, 7]),)"
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+ ]
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+ },
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+ "execution_count": 24,
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+ "metadata": {},
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+ "output_type": "execute_result"
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+ }
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+ ],
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+ "source": [
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+ "# 返回符合条件的位置, 索引值\n",
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+ "np.where(last1 <= 3)"
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+ ]
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+ },
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+ {
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+ "cell_type": "code",
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+ "execution_count": 19,
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+ "metadata": {},
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+ "outputs": [
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+ {
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+ "data": {
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+ "text/plain": [
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+ "array([6, 2, 3, 3, 5, 2, 7, 2, 9, 9])"
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+ ]
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+ },
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+ "execution_count": 19,
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+ "metadata": {},
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+ "output_type": "execute_result"
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+ }
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+ ],
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+ "source": [
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+ "last1"
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+ ]
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+ },
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+ {
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+ "cell_type": "code",
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+ "execution_count": 20,
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+ "metadata": {},
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+ "outputs": [
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+ {
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+ "data": {
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+ "text/plain": [
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+ "array([6, 5])"
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+ ]
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+ },
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+ "execution_count": 20,
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+ "metadata": {},
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+ "output_type": "execute_result"
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+ }
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+ ],
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+ "source": [
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+ "temp2 = last1[(last1 > 3) & (last1 <= 6)]\n",
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+ "temp2"
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+ ]
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+ },
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+ {
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+ "cell_type": "code",
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+ "execution_count": 21,
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+ "metadata": {},
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+ "outputs": [
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+ {
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+ "data": {
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+ "text/plain": [
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+ "array([7, 9, 9])"
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+ ]
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+ },
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+ "execution_count": 21,
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+ "metadata": {},
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+ "output_type": "execute_result"
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+ }
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+ ],
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+ "source": [
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+ "temp3 = last1[last1 > 6]\n",
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+ "temp3"
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+ ]
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+ },
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+ {
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+ "cell_type": "code",
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+ "execution_count": 22,
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+ "metadata": {},
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+ "outputs": [],
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+ "source": [
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+ "last1[last1 <= 3] = 0"
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+ ]
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+ },
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+ {
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+ "cell_type": "code",
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+ "execution_count": 23,
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+ "metadata": {},
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+ "outputs": [
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+ {
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+ "data": {
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+ "text/plain": [
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+ "array([6, 0, 0, 0, 5, 0, 7, 0, 9, 9])"
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+ ]
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+ },
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+ "execution_count": 23,
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+ "metadata": {},
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+ "output_type": "execute_result"
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+ }
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+ ],
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+ "source": [
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+ "last1"
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+ ]
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+ },
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+ {
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+ "cell_type": "code",
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+ "execution_count": 24,
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+ "metadata": {},
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+ "outputs": [],
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+ "source": [
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+ "last1[(last1 > 3) & (last1 <= 6)] = 1"
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+ ]
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+ },
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+ {
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+ "cell_type": "code",
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+ "execution_count": 25,
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+ "metadata": {},
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+ "outputs": [
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+ {
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+ "data": {
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+ "text/plain": [
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+ "array([1, 0, 0, 0, 1, 0, 7, 0, 9, 9])"
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+ ]
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+ },
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+ "execution_count": 25,
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+ "metadata": {},
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+ "output_type": "execute_result"
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+ }
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+ ],
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+ "source": [
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+ "last1"
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+ ]
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+ },
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+ {
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+ "cell_type": "code",
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+ "execution_count": 26,
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+ "metadata": {},
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+ "outputs": [],
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+ "source": [
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+ "last1[last1 > 6] = 2"
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+ ]
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+ },
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+ {
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+ "cell_type": "code",
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+ "execution_count": 32,
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+ "metadata": {},
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+ "outputs": [
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+ {
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+ "data": {
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+ "text/plain": [
|
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+ "array([1, 0, 0, 0, 1, 0, 2, 0, 2, 2])"
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+ ]
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+ },
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+ "execution_count": 32,
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+ "metadata": {},
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+ "output_type": "execute_result"
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+ }
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+ ],
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+ "source": [
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+ "last1 "
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+ ]
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+ },
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+ {
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+ "cell_type": "code",
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+ "execution_count": 33,
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+ "metadata": {},
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+ "outputs": [],
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+ "source": [
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+ "X_train = X1[:, 0:2]"
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+ ]
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+ },
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+ {
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+ "cell_type": "code",
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+ "execution_count": 34,
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+ "metadata": {},
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+ "outputs": [
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+ {
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+ "data": {
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+ "text/plain": [
|
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+ "array([[6, 9],\n",
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+ " [1, 1],\n",
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+ " [8, 7],\n",
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+ " [5, 6],\n",
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+ " [5, 3],\n",
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+ " [8, 8],\n",
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+ " [8, 1],\n",
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+ " [8, 7],\n",
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+ " [1, 2],\n",
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+ " [9, 4]])"
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+ ]
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+ },
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+ "execution_count": 34,
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+ "metadata": {},
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+ "output_type": "execute_result"
|
|
|
+ }
|
|
|
+ ],
|
|
|
+ "source": [
|
|
|
+ "X_train"
|
|
|
+ ]
|
|
|
+ },
|
|
|
+ {
|
|
|
+ "cell_type": "code",
|
|
|
+ "execution_count": 35,
|
|
|
+ "metadata": {},
|
|
|
+ "outputs": [],
|
|
|
+ "source": [
|
|
|
+ "y_train = last1"
|
|
|
+ ]
|
|
|
+ },
|
|
|
+ {
|
|
|
+ "cell_type": "code",
|
|
|
+ "execution_count": 36,
|
|
|
+ "metadata": {},
|
|
|
+ "outputs": [
|
|
|
+ {
|
|
|
+ "data": {
|
|
|
+ "text/plain": [
|
|
|
+ "array([1, 0, 0, 0, 1, 0, 2, 0, 2, 2])"
|
|
|
+ ]
|
|
|
+ },
|
|
|
+ "execution_count": 36,
|
|
|
+ "metadata": {},
|
|
|
+ "output_type": "execute_result"
|
|
|
+ }
|
|
|
+ ],
|
|
|
+ "source": [
|
|
|
+ "y_train"
|
|
|
+ ]
|
|
|
+ },
|
|
|
+ {
|
|
|
+ "cell_type": "code",
|
|
|
+ "execution_count": 37,
|
|
|
+ "metadata": {},
|
|
|
+ "outputs": [
|
|
|
+ {
|
|
|
+ "data": {
|
|
|
+ "text/plain": [
|
|
|
+ "array([[1, 1],\n",
|
|
|
+ " [8, 7],\n",
|
|
|
+ " [5, 6],\n",
|
|
|
+ " [8, 8],\n",
|
|
|
+ " [8, 7]])"
|
|
|
+ ]
|
|
|
+ },
|
|
|
+ "execution_count": 37,
|
|
|
+ "metadata": {},
|
|
|
+ "output_type": "execute_result"
|
|
|
+ }
|
|
|
+ ],
|
|
|
+ "source": [
|
|
|
+ "X_train[y_train == 0] # 分类为0"
|
|
|
+ ]
|
|
|
+ },
|
|
|
+ {
|
|
|
+ "cell_type": "code",
|
|
|
+ "execution_count": 38,
|
|
|
+ "metadata": {},
|
|
|
+ "outputs": [
|
|
|
+ {
|
|
|
+ "data": {
|
|
|
+ "text/plain": [
|
|
|
+ "array([False, True, True, True, False, True, False, True, False,\n",
|
|
|
+ " False])"
|
|
|
+ ]
|
|
|
+ },
|
|
|
+ "execution_count": 38,
|
|
|
+ "metadata": {},
|
|
|
+ "output_type": "execute_result"
|
|
|
+ }
|
|
|
+ ],
|
|
|
+ "source": [
|
|
|
+ "y_train == 0"
|
|
|
+ ]
|
|
|
+ },
|
|
|
+ {
|
|
|
+ "cell_type": "code",
|
|
|
+ "execution_count": 46,
|
|
|
+ "metadata": {},
|
|
|
+ "outputs": [
|
|
|
+ {
|
|
|
+ "data": {
|
|
|
+ "text/plain": [
|
|
|
+ "array([[6, 9],\n",
|
|
|
+ " [5, 3]])"
|
|
|
+ ]
|
|
|
+ },
|
|
|
+ "execution_count": 46,
|
|
|
+ "metadata": {},
|
|
|
+ "output_type": "execute_result"
|
|
|
+ }
|
|
|
+ ],
|
|
|
+ "source": [
|
|
|
+ "X_train[y_train == 1] # 分类为1"
|
|
|
+ ]
|
|
|
+ },
|
|
|
+ {
|
|
|
+ "cell_type": "code",
|
|
|
+ "execution_count": 47,
|
|
|
+ "metadata": {},
|
|
|
+ "outputs": [
|
|
|
+ {
|
|
|
+ "data": {
|
|
|
+ "text/plain": [
|
|
|
+ "array([[8, 1],\n",
|
|
|
+ " [1, 2],\n",
|
|
|
+ " [9, 4]])"
|
|
|
+ ]
|
|
|
+ },
|
|
|
+ "execution_count": 47,
|
|
|
+ "metadata": {},
|
|
|
+ "output_type": "execute_result"
|
|
|
+ }
|
|
|
+ ],
|
|
|
+ "source": [
|
|
|
+ "X_train[y_train == 2] # 分类为2"
|
|
|
+ ]
|
|
|
+ },
|
|
|
+ {
|
|
|
+ "cell_type": "markdown",
|
|
|
+ "metadata": {},
|
|
|
+ "source": [
|
|
|
+ "## 面试题"
|
|
|
+ ]
|
|
|
+ },
|
|
|
+ {
|
|
|
+ "cell_type": "code",
|
|
|
+ "execution_count": 48,
|
|
|
+ "metadata": {},
|
|
|
+ "outputs": [],
|
|
|
+ "source": [
|
|
|
+ "# 奇数替换成-1 不改变arr的值\n",
|
|
|
+ "arr = np.array([0, 1, 2, 3, 4, 5, 6, 7, 8, 9])"
|
|
|
+ ]
|
|
|
+ },
|
|
|
+ {
|
|
|
+ "cell_type": "code",
|
|
|
+ "execution_count": 49,
|
|
|
+ "metadata": {},
|
|
|
+ "outputs": [
|
|
|
+ {
|
|
|
+ "data": {
|
|
|
+ "text/plain": [
|
|
|
+ "array([ 0, -1, 2, -1, 4, -1, 6, -1, 8, -1])"
|
|
|
+ ]
|
|
|
+ },
|
|
|
+ "execution_count": 49,
|
|
|
+ "metadata": {},
|
|
|
+ "output_type": "execute_result"
|
|
|
+ }
|
|
|
+ ],
|
|
|
+ "source": [
|
|
|
+ "np.where(arr % 2 == 1, -1, arr)"
|
|
|
+ ]
|
|
|
+ },
|
|
|
+ {
|
|
|
+ "cell_type": "code",
|
|
|
+ "execution_count": 50,
|
|
|
+ "metadata": {},
|
|
|
+ "outputs": [
|
|
|
+ {
|
|
|
+ "name": "stdout",
|
|
|
+ "output_type": "stream",
|
|
|
+ "text": [
|
|
|
+ "[[0 1 2 3 4]\n",
|
|
|
+ " [5 6 7 8 9]]\n",
|
|
|
+ "[[1 1 1 1 1]\n",
|
|
|
+ " [1 1 1 1 1]]\n"
|
|
|
+ ]
|
|
|
+ }
|
|
|
+ ],
|
|
|
+ "source": [
|
|
|
+ "# 垂直叠加两个数组\n",
|
|
|
+ "a = np.arange(10).reshape(2, -1)\n",
|
|
|
+ "print(a)\n",
|
|
|
+ "b = np.repeat(1, 10).reshape(2, -1)\n",
|
|
|
+ "print(b)"
|
|
|
+ ]
|
|
|
+ },
|
|
|
+ {
|
|
|
+ "cell_type": "code",
|
|
|
+ "execution_count": 54,
|
|
|
+ "metadata": {},
|
|
|
+ "outputs": [
|
|
|
+ {
|
|
|
+ "data": {
|
|
|
+ "text/plain": [
|
|
|
+ "array([[0, 1, 2, 3, 4, 1, 1, 1, 1, 1],\n",
|
|
|
+ " [5, 6, 7, 8, 9, 1, 1, 1, 1, 1]])"
|
|
|
+ ]
|
|
|
+ },
|
|
|
+ "execution_count": 54,
|
|
|
+ "metadata": {},
|
|
|
+ "output_type": "execute_result"
|
|
|
+ }
|
|
|
+ ],
|
|
|
+ "source": [
|
|
|
+ "np.concatenate([a, b], axis = 1)"
|
|
|
+ ]
|
|
|
+ },
|
|
|
+ {
|
|
|
+ "cell_type": "code",
|
|
|
+ "execution_count": 53,
|
|
|
+ "metadata": {},
|
|
|
+ "outputs": [
|
|
|
+ {
|
|
|
+ "data": {
|
|
|
+ "text/plain": [
|
|
|
+ "array([[0, 1, 2, 3, 4, 1, 1, 1, 1, 1],\n",
|
|
|
+ " [5, 6, 7, 8, 9, 1, 1, 1, 1, 1]])"
|
|
|
+ ]
|
|
|
+ },
|
|
|
+ "execution_count": 53,
|
|
|
+ "metadata": {},
|
|
|
+ "output_type": "execute_result"
|
|
|
+ }
|
|
|
+ ],
|
|
|
+ "source": [
|
|
|
+ "np.hstack([a, b])"
|
|
|
+ ]
|
|
|
+ },
|
|
|
+ {
|
|
|
+ "cell_type": "code",
|
|
|
+ "execution_count": 55,
|
|
|
+ "metadata": {},
|
|
|
+ "outputs": [
|
|
|
+ {
|
|
|
+ "data": {
|
|
|
+ "text/plain": [
|
|
|
+ "array([[0, 1, 2, 3, 4],\n",
|
|
|
+ " [5, 6, 7, 8, 9],\n",
|
|
|
+ " [1, 1, 1, 1, 1],\n",
|
|
|
+ " [1, 1, 1, 1, 1]])"
|
|
|
+ ]
|
|
|
+ },
|
|
|
+ "execution_count": 55,
|
|
|
+ "metadata": {},
|
|
|
+ "output_type": "execute_result"
|
|
|
+ }
|
|
|
+ ],
|
|
|
+ "source": [
|
|
|
+ "np.vstack([a, b])"
|
|
|
+ ]
|
|
|
+ },
|
|
|
+ {
|
|
|
+ "cell_type": "code",
|
|
|
+ "execution_count": 56,
|
|
|
+ "metadata": {},
|
|
|
+ "outputs": [
|
|
|
+ {
|
|
|
+ "data": {
|
|
|
+ "text/plain": [
|
|
|
+ "array([[0, 1, 2, 3, 4, 1, 1, 1, 1, 1],\n",
|
|
|
+ " [5, 6, 7, 8, 9, 1, 1, 1, 1, 1]])"
|
|
|
+ ]
|
|
|
+ },
|
|
|
+ "execution_count": 56,
|
|
|
+ "metadata": {},
|
|
|
+ "output_type": "execute_result"
|
|
|
+ }
|
|
|
+ ],
|
|
|
+ "source": [
|
|
|
+ "np.c_[a, b]"
|
|
|
+ ]
|
|
|
+ },
|
|
|
+ {
|
|
|
+ "cell_type": "code",
|
|
|
+ "execution_count": 57,
|
|
|
+ "metadata": {},
|
|
|
+ "outputs": [
|
|
|
+ {
|
|
|
+ "data": {
|
|
|
+ "text/plain": [
|
|
|
+ "array([2, 4])"
|
|
|
+ ]
|
|
|
+ },
|
|
|
+ "execution_count": 57,
|
|
|
+ "metadata": {},
|
|
|
+ "output_type": "execute_result"
|
|
|
+ }
|
|
|
+ ],
|
|
|
+ "source": [
|
|
|
+ "# 求两个集合的交互项\n",
|
|
|
+ "a = np.array([1,2,3,2,3,4,3,4,5,6])\n",
|
|
|
+ "b = np.array([7,2,10,2,7,4,9,4,9,8])\n",
|
|
|
+ "np.intersect1d(a, b)"
|
|
|
+ ]
|
|
|
+ },
|
|
|
+ {
|
|
|
+ "cell_type": "code",
|
|
|
+ "execution_count": 58,
|
|
|
+ "metadata": {},
|
|
|
+ "outputs": [
|
|
|
+ {
|
|
|
+ "data": {
|
|
|
+ "text/plain": [
|
|
|
+ "array([1, 2, 3, 4])"
|
|
|
+ ]
|
|
|
+ },
|
|
|
+ "execution_count": 58,
|
|
|
+ "metadata": {},
|
|
|
+ "output_type": "execute_result"
|
|
|
+ }
|
|
|
+ ],
|
|
|
+ "source": [
|
|
|
+ "# 从数组a中删除数组b中的所有项\n",
|
|
|
+ "a = np.array([1,2,3,4,5])\n",
|
|
|
+ "b = np.array([5,6,7,8,9])\n",
|
|
|
+ "\n",
|
|
|
+ "np.setdiff1d(a, b)"
|
|
|
+ ]
|
|
|
+ },
|
|
|
+ {
|
|
|
+ "cell_type": "code",
|
|
|
+ "execution_count": 59,
|
|
|
+ "metadata": {},
|
|
|
+ "outputs": [
|
|
|
+ {
|
|
|
+ "data": {
|
|
|
+ "text/plain": [
|
|
|
+ "(array([1, 3, 5, 7]),)"
|
|
|
+ ]
|
|
|
+ },
|
|
|
+ "execution_count": 59,
|
|
|
+ "metadata": {},
|
|
|
+ "output_type": "execute_result"
|
|
|
+ }
|
|
|
+ ],
|
|
|
+ "source": [
|
|
|
+ "# 获取a和b元素匹配的位置\n",
|
|
|
+ "a = np.array([1,2,3,2,3,4,3,4,5,6])\n",
|
|
|
+ "b = np.array([7,2,10,2,7,4,9,4,9,8])\n",
|
|
|
+ "\n",
|
|
|
+ "np.where(a == b)"
|
|
|
+ ]
|
|
|
+ },
|
|
|
+ {
|
|
|
+ "cell_type": "code",
|
|
|
+ "execution_count": 62,
|
|
|
+ "metadata": {},
|
|
|
+ "outputs": [
|
|
|
+ {
|
|
|
+ "data": {
|
|
|
+ "text/plain": [
|
|
|
+ "(array([1, 3, 4]),)"
|
|
|
+ ]
|
|
|
+ },
|
|
|
+ "execution_count": 62,
|
|
|
+ "metadata": {},
|
|
|
+ "output_type": "execute_result"
|
|
|
+ }
|
|
|
+ ],
|
|
|
+ "source": [
|
|
|
+ "# 如何从numpy数组中提取给定范围内的所有数字\n",
|
|
|
+ "# 获取5到10之间的所有项目\n",
|
|
|
+ "a = np.array([2, 6, 1, 9, 10, 3, 27])\n",
|
|
|
+ "indexs = np.where((a >= 5) & (a <= 10))\n",
|
|
|
+ "indexs"
|
|
|
+ ]
|
|
|
+ },
|
|
|
+ {
|
|
|
+ "cell_type": "code",
|
|
|
+ "execution_count": 63,
|
|
|
+ "metadata": {},
|
|
|
+ "outputs": [
|
|
|
+ {
|
|
|
+ "data": {
|
|
|
+ "text/plain": [
|
|
|
+ "array([ 6, 9, 10])"
|
|
|
+ ]
|
|
|
+ },
|
|
|
+ "execution_count": 63,
|
|
|
+ "metadata": {},
|
|
|
+ "output_type": "execute_result"
|
|
|
+ }
|
|
|
+ ],
|
|
|
+ "source": [
|
|
|
+ "a[indexs]"
|
|
|
+ ]
|
|
|
+ },
|
|
|
+ {
|
|
|
+ "cell_type": "code",
|
|
|
+ "execution_count": 64,
|
|
|
+ "metadata": {},
|
|
|
+ "outputs": [
|
|
|
+ {
|
|
|
+ "data": {
|
|
|
+ "text/plain": [
|
|
|
+ "array([ 6, 9, 10])"
|
|
|
+ ]
|
|
|
+ },
|
|
|
+ "execution_count": 64,
|
|
|
+ "metadata": {},
|
|
|
+ "output_type": "execute_result"
|
|
|
+ }
|
|
|
+ ],
|
|
|
+ "source": [
|
|
|
+ "a[(a >= 5) & (a <= 10)]"
|
|
|
+ ]
|
|
|
+ },
|
|
|
+ {
|
|
|
+ "cell_type": "code",
|
|
|
+ "execution_count": 65,
|
|
|
+ "metadata": {},
|
|
|
+ "outputs": [
|
|
|
+ {
|
|
|
+ "data": {
|
|
|
+ "text/plain": [
|
|
|
+ "array([[0, 1, 2],\n",
|
|
|
+ " [3, 4, 5],\n",
|
|
|
+ " [6, 7, 8]])"
|
|
|
+ ]
|
|
|
+ },
|
|
|
+ "execution_count": 65,
|
|
|
+ "metadata": {},
|
|
|
+ "output_type": "execute_result"
|
|
|
+ }
|
|
|
+ ],
|
|
|
+ "source": [
|
|
|
+ "# 如何交换二维numpy数组中的两列?\n",
|
|
|
+ "# 在数组arr中交换列0和1\n",
|
|
|
+ "arr = np.arange(9).reshape(3, 3)\n",
|
|
|
+ "arr"
|
|
|
+ ]
|
|
|
+ },
|
|
|
+ {
|
|
|
+ "cell_type": "code",
|
|
|
+ "execution_count": 66,
|
|
|
+ "metadata": {},
|
|
|
+ "outputs": [
|
|
|
+ {
|
|
|
+ "data": {
|
|
|
+ "text/plain": [
|
|
|
+ "array([[1, 0, 2],\n",
|
|
|
+ " [4, 3, 5],\n",
|
|
|
+ " [7, 6, 8]])"
|
|
|
+ ]
|
|
|
+ },
|
|
|
+ "execution_count": 66,
|
|
|
+ "metadata": {},
|
|
|
+ "output_type": "execute_result"
|
|
|
+ }
|
|
|
+ ],
|
|
|
+ "source": [
|
|
|
+ "arr[:, [1, 0, 2]]"
|
|
|
+ ]
|
|
|
+ },
|
|
|
+ {
|
|
|
+ "cell_type": "code",
|
|
|
+ "execution_count": 69,
|
|
|
+ "metadata": {},
|
|
|
+ "outputs": [
|
|
|
+ {
|
|
|
+ "data": {
|
|
|
+ "text/plain": [
|
|
|
+ "array([[3, 4, 5],\n",
|
|
|
+ " [0, 1, 2],\n",
|
|
|
+ " [6, 7, 8]])"
|
|
|
+ ]
|
|
|
+ },
|
|
|
+ "execution_count": 69,
|
|
|
+ "metadata": {},
|
|
|
+ "output_type": "execute_result"
|
|
|
+ }
|
|
|
+ ],
|
|
|
+ "source": [
|
|
|
+ "arr[[1, 0, 2], :]"
|
|
|
+ ]
|
|
|
+ },
|
|
|
+ {
|
|
|
+ "cell_type": "code",
|
|
|
+ "execution_count": 70,
|
|
|
+ "metadata": {},
|
|
|
+ "outputs": [
|
|
|
+ {
|
|
|
+ "data": {
|
|
|
+ "text/plain": [
|
|
|
+ "array([[0, 1, 2],\n",
|
|
|
+ " [3, 4, 5],\n",
|
|
|
+ " [6, 7, 8]])"
|
|
|
+ ]
|
|
|
+ },
|
|
|
+ "execution_count": 70,
|
|
|
+ "metadata": {},
|
|
|
+ "output_type": "execute_result"
|
|
|
+ }
|
|
|
+ ],
|
|
|
+ "source": [
|
|
|
+ "arr = np.arange(9).reshape(3, 3)\n",
|
|
|
+ "arr"
|
|
|
+ ]
|
|
|
+ },
|
|
|
+ {
|
|
|
+ "cell_type": "code",
|
|
|
+ "execution_count": 71,
|
|
|
+ "metadata": {},
|
|
|
+ "outputs": [
|
|
|
+ {
|
|
|
+ "data": {
|
|
|
+ "text/plain": [
|
|
|
+ "array([[6, 7, 8],\n",
|
|
|
+ " [3, 4, 5],\n",
|
|
|
+ " [0, 1, 2]])"
|
|
|
+ ]
|
|
|
+ },
|
|
|
+ "execution_count": 71,
|
|
|
+ "metadata": {},
|
|
|
+ "output_type": "execute_result"
|
|
|
+ }
|
|
|
+ ],
|
|
|
+ "source": [
|
|
|
+ "# 反转行\n",
|
|
|
+ "arr[::-1]"
|
|
|
+ ]
|
|
|
+ },
|
|
|
+ {
|
|
|
+ "cell_type": "code",
|
|
|
+ "execution_count": 72,
|
|
|
+ "metadata": {},
|
|
|
+ "outputs": [
|
|
|
+ {
|
|
|
+ "data": {
|
|
|
+ "text/plain": [
|
|
|
+ "array([[2, 1, 0],\n",
|
|
|
+ " [5, 4, 3],\n",
|
|
|
+ " [8, 7, 6]])"
|
|
|
+ ]
|
|
|
+ },
|
|
|
+ "execution_count": 72,
|
|
|
+ "metadata": {},
|
|
|
+ "output_type": "execute_result"
|
|
|
+ }
|
|
|
+ ],
|
|
|
+ "source": [
|
|
|
+ "# 反转列\n",
|
|
|
+ "arr[:, ::-1]"
|
|
|
+ ]
|
|
|
+ },
|
|
|
+ {
|
|
|
+ "cell_type": "code",
|
|
|
+ "execution_count": 75,
|
|
|
+ "metadata": {},
|
|
|
+ "outputs": [
|
|
|
+ {
|
|
|
+ "data": {
|
|
|
+ "text/plain": [
|
|
|
+ "array([[[[ 0, 1, 2],\n",
|
|
|
+ " [ 3, 4, 5]],\n",
|
|
|
+ "\n",
|
|
|
+ " [[ 6, 7, 8],\n",
|
|
|
+ " [ 9, 10, 11]]],\n",
|
|
|
+ "\n",
|
|
|
+ "\n",
|
|
|
+ " [[[12, 13, 14],\n",
|
|
|
+ " [15, 16, 17]],\n",
|
|
|
+ "\n",
|
|
|
+ " [[18, 19, 20],\n",
|
|
|
+ " [21, 22, 23]]],\n",
|
|
|
+ "\n",
|
|
|
+ "\n",
|
|
|
+ " [[[24, 25, 26],\n",
|
|
|
+ " [27, 28, 29]],\n",
|
|
|
+ "\n",
|
|
|
+ " [[30, 31, 32],\n",
|
|
|
+ " [33, 34, 35]]]])"
|
|
|
+ ]
|
|
|
+ },
|
|
|
+ "execution_count": 75,
|
|
|
+ "metadata": {},
|
|
|
+ "output_type": "execute_result"
|
|
|
+ }
|
|
|
+ ],
|
|
|
+ "source": [
|
|
|
+ "arr = np.arange(36).reshape(3, 2, 2, 3)\n",
|
|
|
+ "arr"
|
|
|
+ ]
|
|
|
+ },
|
|
|
+ {
|
|
|
+ "cell_type": "code",
|
|
|
+ "execution_count": null,
|
|
|
+ "metadata": {},
|
|
|
+ "outputs": [],
|
|
|
+ "source": []
|
|
|
+ }
|
|
|
+ ],
|
|
|
+ "metadata": {
|
|
|
+ "kernelspec": {
|
|
|
+ "display_name": "Python 3 (ipykernel)",
|
|
|
+ "language": "python",
|
|
|
+ "name": "python3"
|
|
|
+ },
|
|
|
+ "language_info": {
|
|
|
+ "codemirror_mode": {
|
|
|
+ "name": "ipython",
|
|
|
+ "version": 3
|
|
|
+ },
|
|
|
+ "file_extension": ".py",
|
|
|
+ "mimetype": "text/x-python",
|
|
|
+ "name": "python",
|
|
|
+ "nbconvert_exporter": "python",
|
|
|
+ "pygments_lexer": "ipython3",
|
|
|
+ "version": "3.11.3"
|
|
|
+ }
|
|
|
+ },
|
|
|
+ "nbformat": 4,
|
|
|
+ "nbformat_minor": 2
|
|
|
+}
|