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?
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.
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
The try/except way is the Pythonic way of doing it, but if you really hate it, see if this serves your purpose:
a = ['hello','1','hi',2,'something','3']
pattern = re.compile(r'^(-?\d+)(\.\d+)?')
b = [float(item) if isinstance(item, str) and re.match(pattern, item)
else item for item in a]
What's about my short example:
a = ['hello','1','hi',2,'something','3']
for i, item in enumerate(a):
if str(item).isdigit():
a[i] = float(item)
print a
"1.0". Not sure if OP plans on having any of those, though.I think this is short and better way :
a = ['hello','1','hi',2,'something','3']
for index,value in enumerate(a):
if isinstance(value,int):
a[index] = float(value)
print a
OUTPUT IS:['hello', '1', 'hi', 2.0, 'something', '3']
