如果列表中的列中的单词在新列中添加Y标志，则为python熊猫

Question

I can't figure out if statements in python pandas.

I have a dataframe df

Category | Count
A           45756
B           5857
C           57876

I create a list and then use it as a hierarchy

list_s = {'A':'Y',
'B':'Y'}
df['Flag'] = df['Category'].replace(list_s)

but I get

Category | Count   | Flag 
A           45756     Y
B           5857      Y
C           57876     C

instead of

Category | Count   | Flag 
A           45756     Y
B           5857      Y
C           57876     

Thank You!

Answer 1

Use map with a lambda function in which you utilize dictionary's get method where you can pass a default value

list_s = {'A':'Y', 'B':'Y'}
df['Flag'] = df['Category'].map(lambda x: list_s.get(x, ''))

print(df)

  Category  Count Flag
0        A  45756    Y
1        B   5857    Y
2        C  57876    

Answer 2

IIUC you can do it this way:

In [8]: df['Flag'] = df['Category'].map(list_s).fillna('')

In [9]: df
Out[9]:
  Category  Count Flag
0        A  45756    Y
1        B   5857    Y
2        C  57876