'New column with values depending on a value of other columns

I have 4 columns (stimA_pos, stimB_pos, stimC_pos, stimD_pos) of strings defining the positions of images (left, right, up, down). Another column shows the string of the chosen image (decision_resp). I would like to create a new column showing the chosen image instead of 'left', 'right, etc. This should be the result (decision_resp_img):

stimA_pos stimB_pos stimC_pos stimD_pos decision_resp decision_resp_img
up left down right left stimB
down up right left down stimA
left down right up right stimC
right left up down down stimD

Thanks for any help!

pandas


Solution 1:[1]

df1.join(df1.reset_index().
 melt(['index' ,'decision_resp'], var_name = 'decision_resp_img').
 query('decision_resp == value').set_index('index')['decision_resp_img'].
 str.replace('_pos', ''))

  stimA_pos stimB_pos stimC_pos stimD_pos decision_resp decision_resp_img
0        up      left      down     right          left             stimB
1      down        up     right      left          down             stimA
2      left      down     right        up         right             stimC
3     right      left        up      down          down             stimD

Solution 2:[2]

df["decision_resp_img"] = df.apply(lambda x: dict(zip((a:=dict(x[["stimA_pos","stimB_pos","stimC_pos","stimD_pos"]])).values(), a.keys()))[x["decision_resp"]].replace("_pos","") , axis=1)
df

output:

    stimA_pos   stimB_pos   stimC_pos   stimD_pos   decision_resp   decision_resp_img
0   up  left    down    right   left    stimB
1   down    up  right   left    down    stimA
2   left    down    right   up  right   stimC
3   right   left    up  down    down    stimD

Sources

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Source: Stack Overflow

Solution Source
Solution 1 onyambu
Solution 2 MoRe

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