How do I add a row to a DF based on a condition checking if a value exists in a column

Question

I try to find a solution, but I can't :(

I have a DF where one of the columns is a "child" and another is "parent".

I need to check if the parent exists in a "child" column as a child itself, If not I want to create a new row where the value from the "parent" field will be entered as a "child" value and all the other values will be entered manually.

a_b_c - child; a_b - parent

a_b - child; a - parent

if a_b exists, do nothing and check next row, if not - create "a_b" child with "a" parent

Thank you soo much :)

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score 0 · Answer 1 · answered Jun 24 '20 at 14:15

I treated your example as a sample dataframe

   child parent
0  a_b_c    a_b
1    a_b      a

The following code extracts the rows in which the parent is not there in the child col

child_exists = df.parent.apply(lambda x: x in df.child.tolist())
df[~child_exists].parent # This will return the parents not present in the child col

How do I add a row to a DF based on a condition checking if a value exists in a column

1 Answers1