Better Way Than Using If-else Statement In Python

Possible Duplicate: Putting a simple if-then statement on one line I am working on a python expression and I want that expression to be compressed than using the if else stateme

Solution 1:

You can do:

s = [1, 2, 3, 4]
print 'y' if len(s) > 5 else 'n'

However I don't think this makes the code more readable (at a glance). Also note that if and else don't create a loop, they are simply statements for control flow. Loops are written using for and while.

Solution 2:

Short, but very obfuscated (don't do this):

print 'ny'[len(s) > 5]

[edit] the reason you should never do this, is because it uses properties of the language that are little known to most people, i.e. that bool is a subclass of int. In most situations where you find yourself writing code like the OP, it's usually better to create a flag variable

s_is_long = len(s) > 5

then you can use any of the more appropriate ways to write the print, e.g.:

print 'y' if s_is_long else 'n'

or

print {True: 'y', False: 'n'}[s_is_long]

or the most readable of all...

if s_is_long:
    print 'y'
else:
    print 'n'

Solution 3:

In this case you could use the try/except block:

try:
    print s.index(5)
except ValueError:
    print "5 not in list"

Solution 4:

Short and clear:

s = [1, 2, 3, 4]
output = {True: 'y',False: 'n'}
print output[len(s) > 5]

Solution 5:

Another variation:

print len(s)>5 and 'y' or 'n'

just added for completness. Don't try this at home! ;-)