[FIXED] How to append the last 4 letters of every item in a dataframe column to a list

Issue

I have an inventory system with two separate SKUs in a single string, example (FT3M-FL3M), I want to make a list called "first_item" and append the first 4 letters (first SKU) to it and do this for every item in the column. Then do the same but with taking the last 4 digits of each string (second SKU)

This is the example dataframe

| Index    | Skus           |
| -------- | -------------- |
| First    | FT3M-FL3M      |
| Second   | FT2M-FL2M      |
| Second   | FT1M-FB1M      |
| Second   | FT4S-FL4S      |
| Second   | FT4S-FB2M      |

This is the code I have:

first_list = []
for i in sku:
first_list.append(i[0:4])
print(first_list)

It clearly doesn't work and I get a massive list.

Solution

If you need a list of first / last n characters of a string inside a pandas column you can try:

# first
my_first = [x[:4] for x in df.wanted_column]

# last
my_last = [x[-4:] for x in df.wanted_column]

This gives you a possibility to filter the list on the fly if needed, for example:

my_filtered = my_first = [x[:4] for x in df.wanted_column if 'some_sku' not in x]

Answered By - Jonas Palačionis

Answer Checked By - Willingham (PHPFixing Volunteer)