How to subset a list, then truncate its elements (Pandas)

Question

I have the following list, which is named my_List:

['SAMNY5PAP01_Max',
 'SAMNY5PAP02_Max',
 'SAMNY5PAP03_Max',
 'SAMNY5PAP01_Avg',
 'SAMNY5PAP02_Avg',
 'SAMNY5PAP03_Avg',
 'DVR_PUC_Max_Sum_SAMNY5PAP01',
 'DVR_PUC_Max_Sum_SAMNY5PAP02',
 'DVR_PUC_Max_Sum_SAMNY5PAP03',
 'DVR_PUC_Max_Count_SAMNY5PAP01',
 'DVR_PUC_Max_Count_SAMNY5PAP02',
 'DVR_PUC_Max_Count_SAMNY5PAP03',
 'DVR_PUC_Average_Sum_SAMNY5PAP01',
 'DVR_PUC_Average_Sum_SAMNY5PAP02',
 'DVR_PUC_Average_Sum_SAMNY5PAP03',
 'DVR_PUC_Average_Count_SAMNY5PAP01',
 'DVR_PUC_Average_Count_SAMNY5PAP02',
 'DVR_PUC_Average_Count_SAMNY5PAP03']

I'd like to:

a) take only the first three elements of my_List list (e.g.

['SAMNY5PAP01_Max', 'SAMNY5PAP02_Max', 'SAMNY5PAP03_Max']

b) then, take only the piece of the element before the '_Max' (e.g. ['SAMNY5PAP01', 'SAMNY5PAP01', 'SAMNY5PAP01']

I know how to do step 'a' above, as follows:

my_List = my_List[0:3]

This returns me:

['SAMNY5PAP01_Max', 'SAMNY5PAP02_Max', 'SAMNY5PAP03_Max']

How can I accomplish step 'b' above?

Thanks!

Answer 1

If you want to get rid of '_Max' you can try this:

my_List = [x[:-4] for x in my_List[:3]]

Or this:

my_List = [x.split("_")[0] for x in my_List[:3]]

Answer 2

If there are other possibilities like _MaxLength, etc. that would throw off indexing solutions, you can use regular expressions to accommodate those scenarios.

import re

[st.group(0) for st in [re.search(r'.*[^_Max]', el) for el in my_List[:3]]]