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python 基础语法入门

python 基础语法入门

作者: 对方正在输出_ace | 来源:发表于2020-08-11 14:35 被阅读0次

1. 列表测试

    num_list=[1,2,3,4,5,6]
    print('num_list:{}'.format(num_list))
    print('num_list[-1]:{}'.format(num_list[-1]))
    print('num_list[-2]:{}'.format(num_list[-2]))
    print('num_list[:3]:{}'.format(num_list[:3]))
    print('num_list[:3:]:{}'.format(num_list[:3:]))
    print('num_list[0:3:]:{}'.format(num_list[0:3:]))
    print('num_list[3:]:{}'.format(num_list[3:]))
    print('num_list[3::]:{}'.format(num_list[3::]))
    print('num_list[::2]:{}'.format(num_list[::2]))
    print('num_list[0::2]:{}'.format(num_list[0::2]))

2.时间测试

import time
import datetime
    ts=time.time()
    date_time=time.localtime(ts)
    print(date_time)
    print(time.strftime("当前时间:%Y-%m-%d %H:%M:%S"))
    print(time.strftime("当前时间:%Y-%m-%d %H:%M:%S",time.localtime(1514829722)))
    time.sleep(10)
    print(time.mktime(time.localtime()))
    current_time=datetime.datetime.now()
    print("默认格式:{}".format(current_time))

3. json 测试

import json
user_info_dict={"aa":"sz",
                    "ag":1,
                    "lag":["p","y"],
                    "if_vip":True,
                    "gender":None}
    json_str=json.dumps(user_info_dict)
    python_dict=json.loads(json_str)
    print(json_str)
    print(type(json_str))
    print(type(user_info_dict))
    print(type(python_dict))

4.正则测试

import re
     str="p j p c"
     rs=re.match("p",str)
     print (rs)
     print (rs.group())
     rs=re.match(".","1")
     print (rs.group())
     rs=re.match("\s","\t")
     print (rs)
     rs=re.match("[ab]","bcc")
     print (rs.group())
     str=r"adb\\abc"
     print (str)
     html_data="<head><title>python</title></head>"
     rs=re.match(r"<(.+)><(.+)>.+</\2></\1>",html_data)
     print(rs)
     rs=re.match(r"<(?P<g1>.+)><(?P<g2>.+)>.+</(?P=g2)></(?P=g1)>",html_data)
     print(rs)
     patten=re.compile("\w{4,10}@163\.com")
     rs=re.match(patten,"python2018@163.com,python2020@163.com")
     print(rs)
     rs=re.match(patten,"abc@123.com")
     print(rs)
     rs=re.search(patten,"python2018@163.com,python2020@163.com")
     print(rs)
     rs=re.findall(patten,"python2018@163.com,python2020@163.com")
     print(rs)
     patten=re.compile("(\w{4,10}@(163|qq)\.com)")
     rs=re.findall(patten,"python2018@163.com,python2020@qq.com")
     print(rs)

5. url访问测试

import urllib
    response=urllib.urlopen("http://www.baidu.com")
    print (response.read().decode("utf8"))

6. numpy测试

import numpy as py
    a=[1,1,2,2,3,3,4,4]
    arr=np.array(a)
    print('a:{}'.format(a))
    print ('arr:{}'.format(arr))
    print ('arr shape:{}'.format(arr.shape))
    b=[[1,2,3,4],[5,6,7,8]]
    arr1=np.array(b)
    print('arr1:{}'.format(arr1))
    print ('arr1 shape:{}'.format(arr1.shape))
    arr1_reshape=arr1.reshape(4,2)
    print('arr1_reshape:{}'.format(arr1_reshape))
    print('arr1:{}'.format(arr1))
    arr1[0,0]=10
    print('arr1:{}'.format(arr1))
    print('arr1_reshape:{}'.format(arr1_reshape))
    arr5=np.arange(15)
    print('arr5:{}'.format(arr5))
    print('arr5[8]:{}'.format(arr5[8]))
    print('arr5[8:12]:{}'.format(arr5[8:12]))
    arr6=np.arange(25).reshape(5,5)
    print('arr6:{}'.format(arr6))#切片索引
    print('arr6[1,2:4]:{}'.format(arr6[1,2:4]))
    print('arr6[1:3,2:4]:{}'.format(arr6[1:3,2:4]))
    print('arr6[:,2:]:{}'.format(arr6[:,2:]))
    print('arr6[::2,2:]:{}'.format(arr6[::2,2:]))
    x=np.array([0,1,2,3,1])  #布尔型索引
    print('x:{}'.format(x))
    print('x==1:{}'.format(x==1))
    print('arr6[[False,True,False,False,True]]:{}'.format(arr6[[False,True,False,False,True]]))
    print('arr6[x==1]:{}'.format(arr6[x==1]))
    print('arr6[x!=1]:{}'.format(arr6[x != 1]))
    print('arr6[~(x==1)]:{}'.format(arr6[~(x == 1)]))
    print ('arr6.sum():{}'.format(arr6.sum())) #求和
    print ('arr6.mean():{}'.format(arr6.mean())) #均值
    print ('arr6.std():{}'.format(arr6.std())) #标准差
    print ('arr6.var():{}'.format(arr6.var()))  #方差
    print ('arr6.max():{}'.format(arr6.max()))  # 最大值
    print ('arr6.min():{}'.format(arr6.min()))  # 最小值
    print ('arr6.cumsum():{}'.format(arr6.cumsum()))  # 累计和
    print ('arr6.cumprod():{}'.format(arr6.cumprod()))  # 累计积
    print ('arr6.argmin():{}'.format(arr6.argmin()))  # 最小元素索引
    print ('arr6.argmax():{}'.format(arr6.argmax()))  # 最大元素索引
    print ('arr6.T:{}'.format(arr6.T)) #矩阵转置
    a = [ [1,0,0],
    [0,2,0],
    [0,0,3] ]
    print (np.linalg.inv(a)) #逆矩阵
    print ('arr6+arr6:{}'.format(arr6+arr6)) #矩阵的加法
    print ('arr6-arr6:{}'.format(arr6 - arr6))  # 矩阵的减法
    print ('矩阵6的点乘:{}'.format(arr6*arr6))
    print ('矩阵6乘矩阵6:{}'.format(arr6.dot(arr6)))
    print ('矩阵6的迹:{}'.format(np.trace(arr6)))
    print ('矩阵6的特征值:{}'.format(np.linalg.eig(arr6)[0]))
    print ('矩阵6的特征向量:{}'.format(np.linalg.eig(arr6)[1]))

7.padnas 测试

import pandas as pd
     s1 = pd.Series([1, 2, 3, 4, 5], index=[1, 2, 3, 4, 5])
     print('s1:{}'.format(s1))
     s1 = pd.Series([1,2,3,4,5])
     print('s1:{}'.format(s1))
     print('s1索引:{}'.format(s1.index))
     print('s1数值:{}'.format(s1.values))
     df=pd.DataFrame([[3,2,np.nan,np.nan],[2,5,3,np.nan],[3,4,5,np.nan],[9,5,3,np.nan]],
                     index=['a','b','c','d'],columns=['one','two','three','four'])
     print ('df:{}'.format(df))
     print ('df按列求和:{}'.format(df.sum()))
     print ('df按行求和:{}'.format(df.sum(axis=1)))
     print ('df去除空值:{}'.format(df.dropna()))
     print ('df条件去除空值:{}'.format(df.dropna(how='all',axis=1)))
     df=df.dropna(how='all',axis=1)
     print ('df用0补全空值:{}'.format(df.fillna(0)))
     print ('df用中位数补全空值:{}'.format(df.fillna(df.median())))
     print ('concat:{}'.format(pd.concat([df,df])))
     print ('append:{}'.format(df.append(df)))
     print ('merge:{}'.format(pd.merge(df, df,left_on='one',right_on='one',how='left')))

8.matplotlib测试

import numpy as np
import matplotlib.pyplot as plt
     x=np.random.randn(1000)
     y=np.random.randn(1000)
     plt.scatter(x,y,color='g',marker='*',alpha=0.5)
     plt.title("Scatter plot for 1000 random data from normal distrbution")
     plt.show()

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