Using a string in one column of a dataframe to reference a value in another column

Trying to use a value from a column in a dataframe (placeholder) to reference a specific column in the same dataframe... Wondering if this is possible. Examples of input and output below:

enter:

Output:

Any help would be greatly appreciated!

Correct answer

Attempt:

df["final"] = df.apply(lambda x: str(x[str(x["placeholder"])]) + "_id", axis=1)
print(df)

Print:

       id     1    2     3  placeholder    final
0    9234   923   12   942            2    12_id
1  203841  1230  438  1029            1  1230_id
2   94532  4380  312   349            3   349_id

If the column's type is integer, remove the inner str():

df["final"] = df.apply(lambda x: str(x[x["placeholder"]]) + "_ID", axis=1)

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