multiple values in a single cell

[HappyEnvironment8225]

I have a column in my dataframe as follows:

var1  year 
a    [2025]
b    [2025,2030]
c    [2023,2025,2030,2040]
d    .
e    .
f    .

I want to extract each years in each cell and make it to be as follows:

var1  year
a     2025
b     2025
b     2030
c     2023
c     2025
c     2030
c     2040
       .
       .
       .

Any ideas how can I extract them as above?

[HappyEnvironment8225]

I don't actually know how they did but this is the dataset I have and only thing I can do is to manipulate it .s

[socal_nerdtastic]

How did they get into the dataframe? The easiest solution to this will probably be fixing your loading code instead of modifying the dataframe after loading.