create new column based on condition

[paul18fr]

you haven't gone to the code

[arvin]

Oops my bad.. I was looking at the previous post and trying to understand

[jefsummers]

Expansion and explanation on my code version. Here we use the dataframe "apply" function to apply a function to the dataframe

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import pandas as pd   def my_transform(x): #function to be applied to the dataframe     if x[0]>4: # refer to dataframe as "x". Test if first column is >4         return x[0] # if >4, return that value     else: #otherwise         return x[1] #return the value from the second column   df = pd.DataFrame(data=[[1,2,3],[4,5,6],[7,8,9]]) #create a simple dataframe with 3 rows and 3 columns df[3] = df.apply(my_transform, axis=1) #calls the function above, apply "by row" rather than by column (axis value) df #display result

Output:
	0	1	2	3
0	1	2	3	2
1	4	5	6	5
2	7	8	9	7