How to extract all UPPER from a string? Python

Question

``` #input my_string = 'abcdefgABCDEFGHIJKLMNOP' ``` how would one extract all the UPPER from a string? ``` #output my_upper = 'ABCDEFGHIJKLMNOP' ```

Accepted Answer

Using list comprehension:

```
>>> s = 'abcdefgABCDEFGHIJKLMNOP'
>>> ''.join([c for c in s if c.isupper()])
'ABCDEFGHIJKLMNOP'
```

Using generator expression:

```
>>> ''.join(c for c in s if c.isupper())
'ABCDEFGHIJKLMNOP
```

You can also do it using regular expressions:

```
>>> re.sub('[^A-Z]', '', s)
'ABCDEFGHIJKLMNOP'
```

Solution