I have a DataFrame like below
df = pd.DataFrame({
'A' : [x,x,x,x,x],
'B' : [1,2,1,1,2]
})
I would like to replace x by y where df['B'] == 2 I know there are lots of ways but what is the shortest code to accomplish this? I believe np.where is one way but can it change value (or overwrite variable) based on values in another column?
Here are some alternatives select by both conditions or using replace with select by one condition:
df = pd.DataFrame({
'A' : ['x'] * 5,
'B' : [1,2,1,1,2]
})
df.loc[df.B.eq(2) & df.A.eq('x'), 'A'] = 'y'
print (df)
A B
0 x 1
1 y 2
2 x 1
3 x 1
4 y 2
Or:
df.A = df.A.mask(df.B.eq(2) & df.A.eq('x'), 'y')
Or:
df.A = df.A.mask(df.B.eq(2), df.A.replace('x','y'))
Or:
df.loc[df['B'].eq(2), 'A'] = df['A'].replace('x', 'y')
Try using loc:
>>> df.loc[df['B'] == 2, 'A'] = df.loc[df['B'] == 2, 'A'].replace('x', 'y')
>>> df
A B
0 x 1
1 y 2
2 x 1
3 x 1
4 y 2
>>>
