python数据框dataframe功能总结（转载）

1.数据框增加一列，df['new'] = test[0]表示给df新增一列，列名为new，整列值为test[0]；

1.  
   import pandas as pd
2.  
    
3.  
   a = {'ip':[1,2,3,4],'name':[0,9,8,77],'time':['qq','ww','ee','rr']}
4.  
   df = pd.DataFrame(a)
5.  
   test = ['qqq','eeee']
6.  
   df['new'] = test[0]
7.  
   print(df)

2.数据框列内容筛选，

df1 = df[df['name'].isin([9,8])]表示筛选name列为9和8的数据框；

df2 = df[~df['name'].isin([9,8])]表示筛选name列不是9和8的数据框，~表示反；

df3 = df[(df['name'] > 9) | (df['name'] < 8)]表示筛选name列大于9或小于8的数据框，|表示或；
df4 = df[(df['ip'] > 2) & (df['ip'] <= 4)]表示筛选ip列大于2且小于等于4的数据框，&表示且。

1.  
   import pandas as pd
2.  
    
3.  
   a = {'ip':[1,2,3,4],'name':[0,9,8,77],'time':['qq','ww','ee','rr']}
4.  
   df = pd.DataFrame(a)
5.  
   df1 = df[df['name'].isin([9,8])]
6.  
   df2 = df[~df['name'].isin([9,8])]
7.  
   df3 = df[(df['name'] > 9) | (df['name'] < 8)]
8.  
   df4 = df[(df['ip'] > 2) & (df['ip'] <= 4)]
9.  
   print(df1)
10.  
    print(df2)
11.  
    print(df3)
12.  
    print(df4)

3.数据框，获取行数、列数及第几行第几列的值

1.  
   import pandas as pd
2.  
    
3.  
   a = {'ip':[1,2,3,4],'name':[0,9,8,77],'time':['qq','ww','ee','rr']}
4.  
   df = pd.DataFrame(a)
5.  
   print(df)
6.  
   colum_size = df.columns.size#列数 2
7.  
   row_size = df.iloc[:,0].size#行数 3
8.  
   num1 = df.iloc[[0]].values[0][0]#第一行第一列的值 1
9.  
   num2 = df.iloc[[1]].values[0][1]#第二行第二列的值 9
10.  
    print(colum_size)
11.  
    print(row_size)
12.  
    print(num1)
13.  
    print(num2)

4.数据框固定列顺序

1.  
   import pandas as pd
2.  
    
3.  
   a = {'ip':[1,2,3,4],'name':[0,8,8,77],'time':['qq','ww','ee','rr']}
4.  
   df = pd.DataFrame(a)
5.  
   b = ['name','ip','time']
6.  
   df1 = df.loc[:,b]
7.  
   print(df1)