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401 lines
13 KiB
401 lines
13 KiB
{
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"cells": [
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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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"# 实践1 python初印象\n",
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"\n",
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"## 学习目标\n",
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"1. 熟悉Jupyter lab交互开发环境\n",
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"2. 掌握Python 语句的编写，运行和修改\n",
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"3. 阅读Python微程序，尝试模仿改写程序"
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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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"## 1. 安装Jupyter lab \n",
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"如要在自己电脑本地使用 Jupyterlab 需要在命令提示符窗口（CMD）先用 Python 的包管理工具 pip 来安装：\n",
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"\n",
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"`pip install jupyterlab` \n",
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"\n",
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"然后就可以用\n",
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"\n",
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"`jupyter lab`\n",
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"\n",
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"来运行 Jupyterlab，打开 notebook 进行交互式编程的尝试。"
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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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"## 2.创建使用Notbook文件\n",
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"\n",
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"（1）Notbook文件 \n",
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"File菜单 -> New Notebook 创建一个新的Notbook文件 \n",
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"\n",
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"（2）单元格 \n",
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"Notbook文件是有若干单元格构成，单元格的类型可区分为：Code（代码）、Markdown、RAW。 \n",
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"\n",
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"Code类型的单元格中可以编写一条或多条python语句。按上方三角形运行（Run）按钮执行，或快捷键Ctrl+Enter；\n",
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"RAW类型的单元格是纯文本；\n",
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"Markdown类型的单元格支持Markdown格式，请自行查阅。 \n",
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"\n",
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"（3）使用工具栏命令可以增加，复制，删除，移动单元格。 "
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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": null,
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"metadata": {},
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"outputs": [],
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"source": [
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"#示例1 一条语句\n",
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"print(\"Hello Python World!\")"
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]
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},
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{
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"cell_type": "raw",
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"metadata": {},
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"source": [
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"说明： \n",
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"（1）print是一个Python标准输出函数，函数的功能是执行“打印”的功能。 \n",
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"（2）\"Hello, Python World!\"是字符串，在一对双引号中你可以输入任意文字，包括中文和标点符号，但使用引号要慎重。 \n",
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"（3）一对圆括号是函数的标志，和print函数名配合使用，不可缺少。 \n",
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"（4）圆括号里的是函数的参数。此处参数是一个字符串，也就是print函数输出的内容。 \n"
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]
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},
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{
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"cell_type": "raw",
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"metadata": {},
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"source": [
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"请在此下方增加一个code单元格，输入一个print命令并执行"
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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": null,
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"metadata": {},
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"outputs": [],
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"source": [
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"# 示例2 多条语句\n",
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"#Fl1-1 重要的事情说三遍\n",
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"print(\"重要的事情说三遍\")\n",
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"print(\"Hello Python World!\")\n",
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"print(\"Hello Python World!\")\n",
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"print(\"Hello Python World!\")"
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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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"## 3.认识程序的语法错误\n",
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"当编写的python程序代码没有遵循Python的语法规定时，会报错显示错误信息。学习阅读错误信息，快速定位错误位置，编写程序的基本功。 \n",
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" File \"C:\\Users\\qtzhu\\AppData\\Local\\Temp/ipykernel_5712/281370357.py\", line 1 \n",
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" print(\"重要的事情说三遍) <-- 出错的语句 \n",
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" ^\n",
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"SyntaxError: EOL while scanning string literal \n",
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"出错的类型:语法错误 文本串没有结束 \n",
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" \n",
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"下面程序有三处语法错误，你能找出来吗？(每找到一个错误，修改后重新执行，阅读错误信息提示)"
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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": null,
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"metadata": {},
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"outputs": [],
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"source": [
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"print(\"重要的事情说三遍)\n",
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"print(\"Hello Python World!\")\n",
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"print(\"Hello Python World!\"\n",
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"prin(\"Hello Python World!\")"
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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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"## 4.阅读Python微程序"
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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": null,
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"metadata": {},
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"outputs": [],
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"source": [
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"#Fl1-2\n",
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"s = 99999 * 99999\n",
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"print(s)"
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]
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},
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{
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"cell_type": "raw",
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"metadata": {},
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"source": [
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"##### 对此程序简单解读如下：\n",
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"（1）s是一个变量，它引用不同数据的值。 \n",
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"（2）\tPython语言允许采用大写字母、小写字母、数字、下划线_和汉字等字符及其组合给变量命名，但名字的首字母不能是数字，中间不能出现空格。 \n",
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"（3）\tPython语言中，“=”表示赋值运算，左侧变量s引用等号右侧的计算结果，包含赋值运算符（=）的语句称为赋值语句。 \n",
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"（4）\tprint函数可以输出字符串，例如\"Hello Python World\"，也可以直接输出变量（如s作为变量名）的值。 \n",
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"（5）\tPython中不需要加符号表示语句结束，换行表示一条语句的结束。 \n",
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"（6）\tFL1-2的程序功能是计算99999*99999并输出结果。 \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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"name": "stdout",
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"output_type": "stream",
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"text": [
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"Apr\n"
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]
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}
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],
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"source": [
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"# Fl1-3\n",
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"months=\"MonFebMarAprMayJunJulAugSepOctNovDec\" \n",
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"monthAbbrev = months[(4-1)*3:(4-1)*3+3]\n",
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"print(monthAbbrev)"
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]
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},
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{
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"cell_type": "raw",
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"metadata": {},
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"source": [
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"##### 对此程序简单解读如下： \n",
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"（1）\"JanFebMarAprMayJunJulAugSepOctNovDec\" 是一个字符串常量，一对西文双引号是字符串常量的界定符，一对西文单引号也是字符串常量的界定符。 \n",
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"（2）months是字符串变量。可以通过[ ]和下标来访问字符串中的一个或连续多个字符。 \n",
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" 一个字符：month[i] ，i表示下标，下标从0开始，month[0]表示第一个字符。 \n",
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" 多个字符：month[a:b]表示下标从a到b-1的子串。当n=1时，month[0:3]表示’Jan’ \n",
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"（3）FL1-3的程序功能是通过计算从字符串months中读出第4月的月份缩写。\n",
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"（4）试将第2句中的4改为1到12的任意整数，观察运行结果。\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": null,
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"metadata": {},
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"outputs": [],
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"source": [
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"# Fl1-4\n",
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"name=input(\"姓名：\")\n",
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"gender=input(\"性别:\")\n",
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"if gender==\"男\":\n",
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" print(\"{}先生,您好!\".format(name))\n",
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"else:\n",
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" print(\"{}女士,您好!\".format(name))"
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]
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},
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{
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"cell_type": "raw",
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"metadata": {},
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"source": [
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"对此程序简单解读如下：\n",
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"（1）input函数是一个标准输入函数，接受从键盘输入的字符串数据。函数的参数是一个字符串。执行input函数，首先会输出字符串，提示用户要输入的数据是什么，然后等待用户键盘输入数据，按回车键结束。程序开始的两条输入语句分别接受姓名和性别，数据类型为字符串。\n",
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"（2）if语句是一条选择语句，根据条件gender==\"男\"为真还是为假，进行不同的处理。\n",
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"（3）“==”是关系运算符”等于” ，判断左右两边是否相等，相等为True，不相等为False。注意和赋值运算符“=” 区分。\n",
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"（4）Python采用严格的“缩进”（指每一行代码开始前的空白区域）来表明程序的格式框架，即表示代码之间的包含和层次关系。两句print语句缩进表示了所属关系。\n",
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"（5）\"{}先生,您好!\".format(name)是格式化的字符串，name变量的值在输出时出现在{}位置。\n",
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"（5）FL1-4的功能是输入姓名和性别，根据性别的不同，选择不同的称呼输出问候语。\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": null,
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"metadata": {},
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"outputs": [],
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"source": [
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"# Fl1-5\n",
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"n=int(input(\"n=\"))\n",
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"s=0\n",
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"for i in range(n+1):\n",
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" s=s+i\n",
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"print(\"s=1+2+...{}={}\".format(n,s))"
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]
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},
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{
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"cell_type": "raw",
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"metadata": {},
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"source": [
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"对此程序简单解读如下：\n",
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"（1）input函数能够接受一个键盘输入的字符串。int函数将输入的字符串转化整数，例如输入100，第一条语句的功能为从键盘接受一个整数100，赋值给变量n。\n",
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"（2）Python通过保留字for实现迭代循环，基本使用方法如下：\n",
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" for <循环变量> in <可迭代对象> :\n",
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" <语句块>\n",
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"（3）range(n+1)函数生成一个0~n的整数序列，变量i遍历取值整数序列0~n中的每一个整数，执行s=s+i，实现将序列中每一个整数累加到s。\n",
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"（4）print函数中使用字符串的format方法构造了一个格式输出串，每一个占位槽{}对应一个format函数的一个参数。此处第一个{}对应n的值，第二个{}对应s的值。\n",
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"（5）FL1-5的程序功能是输入一个n，累计1到n的所有整数的和并输出。\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": null,
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"metadata": {},
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"outputs": [],
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"source": [
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"# Fl1-6\n",
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"nums = [12,50,21,56,8,19]\n",
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"n=len(nums)\n",
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"s=sum(nums)\n",
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"average=s/n\n",
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"print(\"average=\",average)"
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]
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},
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{
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"cell_type": "raw",
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"metadata": {},
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"source": [
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"对此程序简单解读如下：\n",
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"（1）nums是一个列表变量，其中存储了一组整数。\n",
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"（2）len和sum是内置函数，len函数求一个序列的长度，可以计算列表、字符串等对象的长度。sum函数是累加和函数，返回列表nums中所有整数的和。\n",
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"（3“/”是除法运算符,执行除法运算。\n",
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"（4）FL1-6的程序功能是求得一组整数的平均值并输出。\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": null,
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"metadata": {},
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"outputs": [],
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"source": [
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"# Fl1-6-1\n",
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"def mean(numbers):\n",
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" s = 0.0\n",
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" for num in numbers:\n",
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" s = s + num\n",
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" return s / len(numbers)\n",
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"\n",
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"nums = [0,1,2,3,4,5,6,7,8,9]\n",
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"print(mean(nums))"
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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": null,
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"metadata": {},
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"outputs": [],
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"source": [
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"对此程序简单解读如下：\n",
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"（1）nums是一个列表变量，其中存储了一组整数。\n",
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"（2）def定义个一个函数mean，函数有一个列表参数numbers，函数实现的功能是求列表numbers的平均值，return语句返回平均值\n",
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"（3）mean(nums)是调用函数mean的语句，讲列表nums传递（赋值）给列表参数numbers，函数返回nums的平均值。\n",
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"（4）FL1-6的程序功能是求得一组整数的平均值并输出。\n"
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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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"## 小试身手 "
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]
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},
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{
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"cell_type": "raw",
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"metadata": {},
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"source": [
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"（1）使用for语句改写下面程序，实现一下输出。\n",
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"重要的事情说三遍\n",
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"Hello Python World!\n",
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"Hello Python World!\n",
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"Hello Python World!"
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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": null,
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"metadata": {},
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"outputs": [],
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"source": [
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"print(\"重要的事情说三遍\")\n",
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"print(\"Hello Python World!\")\n"
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]
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},
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{
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"cell_type": "raw",
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"metadata": {},
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"source": [
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"（2）改写程序Fl1-2，实现求任意两个整数的乘积并输出。\n",
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" 要求：增加变量a和b，表示乘法运算的2个操作数，改写乘法的表达式。\n",
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" a变量和b变量的值由用户输入，输入两个整数。\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": null,
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"metadata": {},
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"outputs": [],
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"source": [
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"s = 99999 * 99999\n",
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"print(s)"
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]
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},
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{
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"cell_type": "raw",
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"metadata": {},
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"source": [
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"（3）改写程序FL1-3.py，实现输入一个月份，输出对应的英文缩写。"
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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": null,
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"metadata": {},
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"outputs": [],
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"source": [
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"months=\"MonFebMarAprMayJunJulAugSepOctNovDec\" \n",
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"n = 4\n",
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"monthAbbrev = months[(n-1)*3:(n-1)*3+3]\n",
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"print(monthAbbrev)"
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]
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},
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{
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"cell_type": "raw",
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"metadata": {},
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"source": [
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"(4)改写程序FL1-3.py，实现顺序输出12月份对应的英文缩写。"
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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": null,
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"metadata": {},
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"outputs": [],
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"source": [
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"months=\"MonFebMarAprMayJunJulAugSepOctNovDec\" \n",
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"n = 4\n",
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"monthAbbrev = months[(n-1)*3:(n-1)*3+3]\n",
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"print(monthAbbrev)"
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]
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}
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],
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"metadata": {
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"kernelspec": {
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"display_name": "Python 3 (ipykernel)",
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"language": "python",
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"name": "python3"
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},
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"language_info": {
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"codemirror_mode": {
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"name": "ipython",
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"version": 3
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},
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"file_extension": ".py",
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"mimetype": "text/x-python",
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"name": "python",
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"nbconvert_exporter": "python",
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"pygments_lexer": "ipython3",
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"version": "3.9.5"
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}
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},
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"nbformat": 4,
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"nbformat_minor": 4
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}
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