import os
os.chdir(r"C:\Users\Hans\Desktop\pandas test")
import pandas as pd
df = pd.read_csv("pandas test.txt",sep= "\t",names =['test01','test2','test3'] )
#pd.read_csv可以读取txt，sep是以什么作为列的分隔符，names = 即指定的列名。
print(df)

import pandas as pd
import numpy as np
s1 = pd.Series([1,'a',5.2,7],index = ['a','c','d','f'])
print(s1)
print(s1.index)
#根据字典创建Series
s2 = pd.Series({'a1':123,'b2':342,'c3':321,'f2':567})
print(s2)
print(s2[['a1','f2']])#根据多个字典创建Series
data = {'state':['x1','x2','x3','x4'],'year':[2001,2002,2003,2004],'pop':[1.2,1.5,1.6,2.0]}
s3 = pd.DataFrame(data)
print(s3)

import pandas as pd
import numpy as np
#赋值操作
data = {'state':['x1','x2','x3','x4'],'year':[2001,2002,2003,2004],'pop':[1.2,1.5,1.6,2.0]}
df = pd.DataFrame(data)
print(df)
#赋值，且选择根据一定的规则进行赋值
df.loc[:,'aaa'] = df['year']-df['pop']
#注意这里需要：,如果不加：则是新增加一行，不是新增加一列
print(df)
#同时新添加多个列，但是原来的df表值不变，等于新生成一个df表
df01 = df.assign(M1 = lambda x :x['year']*10/200+21,M2 = lambda x : x['pop']*10
)
print("*"*50)
print(df01)