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Example of using sort_values ​​isin in pandas DataFrame

零下一度
零下一度Original
2017-05-25 11:16:464674browse

1. In the DataFrame of pandas, we often need to select rows with specified conditions based on a certain attribute. In this case, the isin method is particularly effective.

##

import pandas as pd
df = pd.DataFrame([[1,2,3],[1,3,4],[2,4,3]],index = ['one','two','three'],columns = ['A','B','C'])
print df
#        A  B  C
# one    1  2  3
# two    1  3  4
# three  2  4  3

At this time, suppose we select the row with a value of 1 in column A,

mask = df['A'].isin([1]) #括号中必须为list
print mask
# one       True
# two       True
# three    False
# Name: A, dtype: bool
print df[mask]
#      A  B  C
# one  1  2  3
# two  1  3  4

2. How to sort the DataFrame in pandas by the first keyword and the second keyword, you can use ## here #sort_values, which is sort_index in the old version.

##

import pandas as pd
df = pd.DataFrame([[1,2,3],[2,3,4],[2,4,3],[1,3,7]],
                  index = ['one','two','three','four'],columns = ['A','B','C'])
print df
#        A  B  C
# one    1  2  3
# two    2  3  4
# three  2  4  3
# four   1  3  7
df.sort_values(by=['A','B'],ascending=[0,1],inplace=True)
print df
#        A  B  C
# two    2  3  4
# three  2  4  3
# one    1  2  3
# four   1  3  7
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