如何将字符串中的数字转换为实际数字

Question

i have been given a string of numbers and have been tasked to reproduce only the numbers in the string with a funcion that prints within the function which i was able to do with the following.

# function that prints, no return the values in list
def reprint (f) :
    for numbers in (f):
        tokens = numbers.split(',')
        for values in tokens :

            print values,
        print


#Main        
stringlist =["1,25,999",
             "123.4,56.7890,13.571",
             "1,23.45,6,7.8"]

reprint (stringlist)

Returns

1 25 999
123.4 56.7890 13.571
1 23.45 6 7.8

The trick though is for floats to print with 2 decimal places and thats where i get stuck. I tried to add something like

if '.' in values :
    print "%.2f" % (values)
else print "%d" % (values)

but that didnt work, i get an error saying that print "3%d" % (values) TypeError: %d format: a number is required, not str. Any ideas on how to get the string treated as numbers?

EXPECTED Output =

1 25 999
123.40 56.79 13.57
1 23.45 6 7.80

Answer 1

Use ast.literal_eval to convert those strings into tuple of integers and floats and then use isinstance to check whether it's an int or float :

>>> from ast import literal_eval
for item in stringlist:
    tup =  literal_eval(item)
    for x in tup:
        if isinstance(x, float):
            print format(x, '.2f'),
        elif isinstance(x, int):
            print format(x, 'd'),
    print
...     
1 25 999
123.40 56.79 13.57
1 23.45 6 7.80

Answer 2

Use float() to convert to float number and int() to convert to an integer one.

if '.' in values :
   print "%.2f" % float(values)
else:
   print "%d" % int(values)

Answer 3

You could replace

print values,

with

if '.' in values:
   print '%.2f' % float(values),
else:
   print values,

Answer 4

You could do something like this:

>>> stringlist
['1,25,999', '123.4,56.7890,13.571', '1,23.45,6,7.8']
>>> for line in stringlist:
...     for s in line.split(','):
...         if '.' in s:
...             try:
...                 f=float(s)
...             except ValueError:
...                 print '{} is not a float'
...             else:
...                 print '{:.2f}'.format(f),
...         else:
...             try:
...                 i=int(s)
...             except ValueError:    
...                 print '{} is not an int'.format(s)
...             else:
...                 print i,
...      print