I have a df with one column containing a list of strings like so:

```
    'Name'     'Method'
1   foo        ['car', 'truck', 'transportation::plane']
2   bar        ['car', 'transportation::helicopter', 'boat']
3   baz        ['transportation::car', 'helicopter', 'boat']

```

I only want to keep the items in the lists under methods that contain "::" so that I get something like this:

```
    'Name'     'Method'
1   foo        ['transportation::plane']
2   bar        ['transportation::helicopter']
3   baz        ['transportation::car']

```

I know I could make a for loop to iterate through each list and then use list comprehension, but I feel like there must be a method that doesn't involve using a for loop. I tried the following

```
for j in range(len(df['Method'])):
    df['Method'].iloc[j] = [x for x in df['Method'].iloc[j] if "::" in x]

```

and it takes much longer to run than I would like.