strings

[Scribe]

Hi
Somewhat new to Python and would appreciated some help in selecting the
best builtins to achieve what I want.
I pass a string to a function, it is either
empty
spaces
alpha and digits
or
a decimal ie. 5,789.88
if it is a decimal I want to return the number without the commer any
others return 0.
Should be simple or maybe I am.
Any help apreciated.

 

[Nick Welch]

if it is a decimal I want to return the number without the commer any
others return 0.

"commer"?

str.isdigit() should do most of it for you.

def foo(mystr):
if mystr.isdigit():
return "the number without the commer (??) "
else:
return 0

 

[Peter Otten]

Hi
Somewhat new to Python and would appreciated some help in selecting the
best builtins to achieve what I want.
I pass a string to a function, it is either
empty
spaces
alpha and digits
or
a decimal ie. 5,789.88
if it is a decimal I want to return the number without the commer any
others return 0.
Should be simple or maybe I am.
Any help apreciated.

import locale

locale.setlocale(locale.LC_ALL, ("en", None))

def strtofloat(s):
try:
return locale.atof(s)
#return float(s.replace(",", ""))
except ValueError:
return 0.0


for s in "a 0 12 123.4 12,345.67 12,24a".split():
print s, "->", strtofloat(s)

Output:
a -> 0.0
0 -> 0.0
12 -> 12.0
123.4 -> 123.4
12,345.67 -> 12345.67
12,24a -> 0.0

Peter

 

[Alex Martelli]

Hi
Somewhat new to Python and would appreciated some help in selecting the
best builtins to achieve what I want.
I pass a string to a function, it is either
empty
spaces
alpha and digits
or
a decimal ie. 5,789.88
if it is a decimal I want to return the number without the commer any
others return 0.
Should be simple or maybe I am.
Any help apreciated.

def scribefun(astring):
try: return int(float(astring.replace(',','')))
except ValueError: return 0

This assumes you want to return e.g. 5789 for '5,789.88', i.e.,
an integer truncating the "decimal" (otherwise omit the int()).

Only possible issue is if the "alpha and digits" specifically
include an 'e' as the only "alpha", which builtin float() would
take as an indication of exponential notation; so for example
this would return 100, not 0, for '1e2'. If this is a problem
(unclear from your specs) it ain't all that hard to fix of course.


Alex