I have data:

ID  merk_ac1  merk_ac2 merk_ac3
1   a         NA       NA
2   NA        b        NA
3   NA        a        b
4   a,b       NA       c

I tried using combine_first() but not cover the multiple values. I want the result like:

ID  merk_ac1  merk_ac2 merk_ac3 merk_ac
1   a         a                 a 
2             b                 b
3             a        b        a,b
4   a,b                c        a,b,c

CodePudding user response：

What about something like:

import numpy as np
import panas as pd

df['merk_ac'] = df.apply(lambda x: [element for element in x if ~np.isnan(element)],axis = 1)

assuming that in merk_ac you want a list with all the elements from the different columns of the original data frame

CodePudding user response：

You can use apply to concatenate string from multiple columns using join

import pandas as pd

a = ["a", pd.NA, pd.NA, "a,b"]
b = [pd.NA, "b", "a", pd.NA]
c = [pd.NA, pd.NA, "b", "c"]

df = pd.DataFrame({"a": a, "b": b, "c": c})
df["combined"]=df.apply(lambda row: ",".join([elem for elem in row if not pd.isna(elem)]), axis=1)
df.head()

OUTPUT: