{
"cells": [
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## while循环：计算10以内自然数的和"
]
},
{
"cell_type": "code",
"execution_count": 1,
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"s=45\n"
]
}
],
"source": [
"i = 1\n",
"s = 0\n",
"while i<10:\n",
" s += i\n",
" i += 1\n",
"print(\"s=\"+`s`)"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## while循环：输入一个自然数，求其除了1和本身外的所有因子"
]
},
{
"cell_type": "code",
"execution_count": 4,
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"输入一个自然数,程序将求出它所有的因子14\n",
"因子是：2 7 \n"
]
}
],
"source": [
"i = 0\n",
"j = 2\n",
"stro = '因子是：'\n",
"i = input(\"输入一个自然数,程序将求出它所有的因子\")\n",
"while j < i:\n",
" if i % j == 0:\n",
" stro += `j` + ' '\n",
" j+=1\n",
"print stro"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## break语句演示"
]
},
{
"cell_type": "code",
"execution_count": 5,
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"B\n",
"B\n",
"B\n",
"B\n",
"B\n",
"B\n",
"B\n",
"B\n",
"B\n",
"B\n",
"I\n",
"T\n",
"T\n",
"T\n",
"T\n",
"T\n",
"T\n",
"T\n",
"T\n",
"T\n",
"T\n"
]
}
],
"source": [
"for s in \"BIT\":\n",
" for i in range(10):\n",
" print s\n",
" if s == \"I\":\n",
" break"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## continue语句演示"
]
},
{
"cell_type": "code",
"execution_count": 6,
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"P\n",
"Y\n",
"H\n",
"O\n",
"N\n"
]
}
],
"source": [
"for s in \"PYTHON\":\n",
" if s == \"T\":\n",
" continue\n",
" print s"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## 列表"
]
},
{
"cell_type": "code",
"execution_count": 18,
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"100011\n",
"Beijing\n",
"3.14\n"
]
}
],
"source": [
"items = [] #声明一个空列表\n",
"items.append(100011)\n",
"items.append('Beijing')\n",
"items.append(3.14)\n",
"print items[0]\n",
"print items[1]\n",
"print items[2]"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"### append 与 extend 方法"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"#### append 表示把某个数据当做新元素 追加 到列表的最后面，它的参数可以是任意对象"
]
},
{
"cell_type": "code",
"execution_count": 19,
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"[1, 2, 3, [4, 5]]\n"
]
}
],
"source": [
"x = [1, 2, 3]\n",
"y = [4, 5]\n",
"x.append(y)\n",
"print(x)"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"#### extend 的参数必须是一个可迭代对象，表示把该对象里面的所有元素逐个地追加到列表的后面"
]
},
{
"cell_type": "code",
"execution_count": 20,
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"[1, 2, 3, 4, 5]\n"
]
}
],
"source": [
"x = [1, 2, 3]\n",
"y = [4, 5]\n",
"x.extend(y)\n",
"print(x)"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"### 向列表中插入元素"
]
},
{
"cell_type": "code",
"execution_count": 32,
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"[100011, 'Beijing', '\\xe5\\x9c\\x86\\xe5\\x91\\xa8\\xe7\\x8e\\x87', 3.14]\n"
]
}
],
"source": [
"items = []\n",
"items.append(100011)\n",
"items.append('Beijing')\n",
"items.append(3.14)\n",
"items.insert(2,'圆周率')\n",
"print items"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"### 删除或清空列表中的记录"
]
},
{
"cell_type": "code",
"execution_count": 54,
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"['a', 'b', 'd']\n",
"['a', 'b', 'd', 'a']\n",
"['b', 'd', 'a']\n"
]
}
],
"source": [
"my_list = ['a', 'b', 'c', 'd']\n",
"my_list.pop(2) #删除索引为 2 的元素\n",
"print my_list\n",
"my_list.append('a')\n",
"print my_list\n",
"my_list.remove('a') #remove 移除某个元素，而且只能移除第一次出现的元素\n",
"print my_list"
]
},
{
"cell_type": "code",
"execution_count": 26,
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"['a', 'b', 'c']\n"
]
}
],
"source": [
"my_list = ['a', 'b', 'c', 'd']\n",
"my_list.pop() #删除尾部元素\n",
"print my_list"
]
},
{
"cell_type": "code",
"execution_count": 55,
"metadata": {},
"outputs": [
{
"data": {
"text/plain": [
"3"
]
},
"execution_count": 55,
"metadata": {},
"output_type": "execute_result"
}
],
"source": [
"a = [4, 3, 5]\n",
"a.pop(1)"
]
},
{
"cell_type": "code",
"execution_count": 57,
"metadata": {
"collapsed": true
},
"outputs": [],
"source": [
"a = [4, 3, 5]\n",
"del a[1]"
]
},
{
"cell_type": "code",
"execution_count": 56,
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"['a', 'b', 'c', 'd']\n",
"[]\n"
]
},
{
"ename": "NameError",
"evalue": "name 'my_list' is not defined",
"output_type": "error",
"traceback": [
"\u001b[0;31m---------------------------------------------------------------------------\u001b[0m",
"\u001b[0;31mNameError\u001b[0m Traceback (most recent call last)",
"\u001b[0;32m<ipython-input-56-3938ed1f7307>\u001b[0m in \u001b[0;36m<module>\u001b[0;34m()\u001b[0m\n\u001b[1;32m 4\u001b[0m \u001b[0;32mprint\u001b[0m \u001b[0mmy_list\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m 5\u001b[0m \u001b[0;32mdel\u001b[0m \u001b[0mmy_list\u001b[0m \u001b[0;31m#删除列表\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0;32m----> 6\u001b[0;31m \u001b[0;32mprint\u001b[0m \u001b[0mmy_list\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m",
"\u001b[0;31mNameError\u001b[0m: name 'my_list' is not defined"
]
}
],
"source": [
"my_list = ['a', 'b', 'c', 'd']\n",
"print my_list\n",
"my_list = [] #清空列表\n",
"print my_list\n",
"del my_list #删除列表\n",
"print my_list"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"### 二级索引"
]
},
{
"cell_type": "code",
"execution_count": 30,
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"['Triangle:', '3,4,5', 6.0]\n",
"6.0\n"
]
}
],
"source": [
"lst_shape = [['Triangle:','3,4,5',6.0],['Rect:','5,6',30],['Circle:','5',78.5]]\n",
"print lst_shape[0]\n",
"print lst_shape[0][2]"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"### 检查列表是否为空"
]
},
{
"cell_type": "code",
"execution_count": 34,
"metadata": {
"collapsed": true
},
"outputs": [],
"source": [
"if len(items) == 0:\n",
" print(\"空列表\")"
]
},
{
"cell_type": "code",
"execution_count": 35,
"metadata": {
"collapsed": true
},
"outputs": [],
"source": [
"if items == []:\n",
" print(\"空列表\")"
]
},
{
"cell_type": "code",
"execution_count": 36,
"metadata": {
"collapsed": true
},
"outputs": [],
"source": [
"if not items:\n",
" print(\"空列表\")"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"### 切片"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"切片用于获取列表中指定范的子集，语法非常简单:"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": true
},
"outputs": [],
"source": [
"items[start:end:step] #从 start 到 end-1 位置之间的元素。step 表示步长，默认为1，表示连续获取，如果 step 为 2 就表示每隔一个元素获取。"
]
},
{
"cell_type": "code",
"execution_count": 38,
"metadata": {},
"outputs": [
{
"data": {
"text/plain": [
"[4, 5, 6, 7, 8]"
]
},
"execution_count": 38,
"metadata": {},
"output_type": "execute_result"
}
],
"source": [
"a = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]\n",
"a[3:8] # 第3到第8位置之间的元素"
]
},
{
"cell_type": "code",
"execution_count": 39,
"metadata": {},
"outputs": [
{
"data": {
"text/plain": [
"[4, 6, 8]"
]
},
"execution_count": 39,
"metadata": {},
"output_type": "execute_result"
}
],
"source": [
"a = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]\n",
"a[3:8:2] # 第3到第8位置之间的元素，每隔一个元素获取"
]
},
{
"cell_type": "code",
"execution_count": 40,
"metadata": {},
"outputs": [
{
"data": {
"text/plain": [
"[1, 2, 3, 4, 5]"
]
},
"execution_count": 40,
"metadata": {},
"output_type": "execute_result"
}
],
"source": [
"a = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]\n",
"a[:5] #省略start表示从第0个元素开始"
]
},
{
"cell_type": "code",
"execution_count": 41,
"metadata": {},
"outputs": [
{
"data": {
"text/plain": [
"[4, 5, 6, 7, 8, 9, 10]"
]
},
"execution_count": 41,
"metadata": {},
"output_type": "execute_result"
}
],
"source": [
"a = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]\n",
"a[3:] #省略end表示到最后一个元素"
]
},
{
"cell_type": "code",
"execution_count": 42,
"metadata": {},
"outputs": [
{
"data": {
"text/plain": [
"[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]"
]
},
"execution_count": 42,
"metadata": {},
"output_type": "execute_result"
}
],
"source": [
"a = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]\n",
"a[::] #都省略相当于拷贝一个列表"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"### 获取列表中的最后一个元素"
]
},
{
"cell_type": "code",
"execution_count": 43,
"metadata": {},
"outputs": [
{
"data": {
"text/plain": [
"10"
]
},
"execution_count": 43,
"metadata": {},
"output_type": "execute_result"
}
],
"source": [
"a = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]\n",
"a[-1]"
]
},
{
"cell_type": "code",
"execution_count": 44,
"metadata": {},
"outputs": [
{
"data": {
"text/plain": [
"10"
]
},
"execution_count": 44,
"metadata": {},
"output_type": "execute_result"
}
],
"source": [
"a = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]\n",
"a[len(a)-1]"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"### 连接两个列表"
]
},
{
"cell_type": "code",
"execution_count": 46,
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"[1, 2, 3, 4, 5, 6]\n"
]
}
],
"source": [
"listone = [1, 2, 3]\n",
"listtwo = [4, 5, 6]\n",
"\n",
"mergedlist = listone + listtwo\n",
"\n",
"print(mergedlist)"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## for循环"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": true
},
"outputs": [],
"source": [
"for i in range（N）:\n",
" 循环体LB\n",
"#函数range（N）的意义在于生成一个0到N-1的数字列表\n",
"for i in range（N，M）#range（N，M）的范围是从N到M-1。其中i的取值范围是[N,M)"
]
},
{
"cell_type": "code",
"execution_count": 60,
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"153\n",
"370\n",
"371\n",
"407\n"
]
}
],
"source": [
"# 输出水仙花数\n",
"for i in range(100,1000):\n",
" hun = i/100\n",
" ten = (i-hun*100)/10\n",
" num = i%10\n",
" if i == hun**3 + ten**3 + num**3:\n",
" print i"
]
},
{
"cell_type": "code",
"execution_count": 62,
"metadata": {},
"outputs": [
{
"ename": "SyntaxError",
"evalue": "invalid syntax (<ipython-input-62-9fd3efae8c5f>, line 1)",
"output_type": "error",
"traceback": [
"\u001b[0;36m File \u001b[0;32m\"<ipython-input-62-9fd3efae8c5f>\"\u001b[0;36m, line \u001b[0;32m1\u001b[0m\n\u001b[0;31m for rec in My_list：\u001b[0m\n\u001b[0m ^\u001b[0m\n\u001b[0;31mSyntaxError\u001b[0m\u001b[0;31m:\u001b[0m invalid syntax\n"
]
}
],
"source": [
"for rec in My_list:\n",
" 循环体LB\n",
"#用for循环遍历列表"
]
},
{
"cell_type": "code",
"execution_count": 63,
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"1\n",
"2\n",
"3\n",
"4\n",
"5\n",
"6\n",
"7\n",
"8\n",
"9\n",
"10\n"
]
}
],
"source": [
"a = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]\n",
"for r in a:\n",
" print r"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"补充：eval()函数：可简单理解为将string变成算术表达式来执行"
]
},
{
"cell_type": "code",
"execution_count": 64,
"metadata": {},
"outputs": [
{
"data": {
"text/plain": [
"8"
]
},
"execution_count": 64,
"metadata": {},
"output_type": "execute_result"
}
],
"source": [
"eval('3+5')"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"在Python3中可以用eval(input())将输入的内容转换为数字"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": true
},
"outputs": [],
"source": []
}
],
"metadata": {
"kernelspec": {
"display_name": "Python 2",
"language": "python",
"name": "python2"
},
"language_info": {
"codemirror_mode": {
"name": "ipython",
"version": 2
},
"file_extension": ".py",
"mimetype": "text/x-python",
"name": "python",
"nbconvert_exporter": "python",
"pygments_lexer": "ipython2",
"version": "2.7.13"
},
"toc": {
"nav_menu": {},
"number_sections": true,
"sideBar": true,
"skip_h1_title": false,
"toc_cell": false,
"toc_position": {},
"toc_section_display": "block",
"toc_window_display": false
}
},
"nbformat": 4,
"nbformat_minor": 2
}