convert list of string and number to string and float

Question

Say I have a list like this:

a = ['hello','1','hi',2,'something','3'] 

I want to convert the numbers in the list into float while keeping the strings.

I wrote this:

for i in a:
    try:
        i = float(i)
    except ValueError:
        pass

Is there a more efficient and neat way to do this?

Answer 1

Based on what you've already tried:

a = ['hello', '1.0', 'hi', 2, 'blah blah', '3']

def float_or_string(item):
    try:
        return float(item)
    except ValueError:
        return item


a = map(float_or_string, mylist)

Should do the trick. I'd say that a try:... except:... block is both a) efficient and b) neat. As halex pointed out, map() does not change the list in place, it returns a new list, and you set a equal to it.

Answer 2

You're changing the value of the variable i -> The content of the array a does not change! If you want to change the values in the array, you should rather implement it like this:

for index, value in enumerate(a):
    try :
        a[index] = float(value)
    except ValueError :
        pass