Start of main content## More like this

Merges two or more lists into a list of lists, combining elements from each of the input lists based on their positions.

- Use
`max()`

combined with a list comprehension to get the length of the longest list in the arguments. - Use
`range()`

in combination with the`max_length`

variable to loop as many times as there are elements in the longest list. - If a list is shorter than
`max_length`

, use`fill_value`

for the remaining items (defaults to`None`

). `zip()`

and`itertools.zip_longest()`

provide similar functionality to this snippet.

```
def merge(*args, fill_value = None):
max_length = max([len(lst) for lst in args])
result = []
for i in range(max_length):
result.append([
args[k][i] if i < len(args[k]) else fill_value for k in range(len(args))
])
return result
```

```
merge(['a', 'b'], [1, 2], [True, False]) # [['a', 1, True], ['b', 2, False]]
merge(['a'], [1, 2], [True, False]) # [['a', 1, True], [None, 2, False]]
merge(['a'], [1, 2], [True, False], fill_value = '_')
# [['a', 1, True], ['_', 2, False]]
```

### List difference based on function

Python, List

Returns the difference between two lists, after applying the provided function to each list element of both.

### List symmetric difference based on function

Python, List

Returns the symmetric difference between two lists, after applying the provided function to each list element of both.

### List union based on function

Python, List

Returns every element that exists in any of the two lists once, after applying the provided function to each element of both.