I have a list 'list\_of\_categories\_train' having values:
==========================================================

```
0                                      [Men, Tops, T-shirts]
1          [Electronics, Computers & Tablets, Components ...
2                            [Women, Tops & Blouses, Blouse]
3                   [Home, Home DÃ©cor, Home DÃ©cor Accents]
4                                [Women, Jewelry, Necklaces]
                                 ...                        
1048570                                 [Kids, Other, Other]
1048571           [Other, Daily & Travel items, Health Care]
1048572    [Women, Athletic Apparel, Pants, Tights, Leggi...
1048573                       [Men, Shoes, Fashion Sneakers]
1048574                    [Kids, Toys, Dolls & Accessories]
Name: category_name, Length: 1048575, dtype: object

```

I need to pick 1st word of each list and put it into dataframe. But it takes hours. what is the fastest way to do that?
My Code is:

```
i=0
while i <= len(list_of_categories_train)  :  
    data_train['noOfCategories']= list_of_categories_train[i][0]
    i=i+1

```