I have a list where each element is stored as a string
A = ['a', 'b', 'c', '100','200.6']
How can I extract only the numeric elements
[100, 200.6]
I cannot convert the elements using [float(i) for i in temp] as string elements cannot be converted to float. I need to retain the string elements as they are and just filter out the numeric elements.
For simple cases, you can use re.match to check if the element matches a number with decimal point and then convert it to a float
>>> A = ['a', 'b', 'c', '100', '200.6']
>>> import re
>>> [float(e) for e in A if re.match(r'\d+\.?\d*$', e)]
[100.0, 200.6]
But as folks have pointed out in the comments, if you floats in unconventional formats, you have to write a utility function to convert the string to float when possible or return None and then filter the list
>>> def is_float(n):
... try:
... return float(n)
... except:
... return None
...
>>>
>>> A = ['a', 'b', 'c', '100', '200.6']
>>> list(filter(is_float, A))
['100', '200.6']
'10_000' can be cast to float. This article comes to mind here.
Filterdef is_number(s): try: float(s) return True except ValueError: return False filter(is_number, A)this is cleaner than adding your own for loop