Creating a function by using lambda and apply

Question

I want to create a function by using lambda and apply tools. In this function, it should return "1.30" or "0" according to the condition. If in the column value is greater than 30, it returns "1.30" not "0". After that, I have to implement this function to the elements in the column.

I've tried something but I could not. Let me show you what I did before:

def catch(column_name):
if column_name < 30:
    print("1.30") 
else:
    print("0")

df.loc[:,df.columns.str.contains("age")].apply(lambda catch: catch > 30)

When I type like that, just shows me True or False. I don't want this

Answer 1

Anoher solution based on np.where to avoid ambiguous error of pandas when returning a list of True and False. Please see: https://www.learndatasci.com/solutions/python-valueerror-truth-value-series-ambiguous-use-empty-bool-item-any-or-all/

>>> import pandas as pd
>>> import numpy as np

>>> data = {"col1": [1,2,3,4,5], "age_1": [50,20,60,40,10], "age_2": [5,70,60,3,10]}
>>> df = pd.DataFrame(data)
>>> df

col1 age_1 age_2
1    50    5
2    20    70
3    60    60
4    40    3
5    10    10

>>> df[['age_1_p', "age_2_p"]] = np.where(df.iloc[:,df.columns.str.contains("age")]>30, 1.3, 0)
>>> df[['age_1_p', "age_2_p"]]

age_1_p age_2_p
1.3     0.0
0.0     1.3
1.3     1.3
1.3     0.0
0.0     0.0