Simple if-else statement in Python

Question

I am writing a script that, if an array's elements are the subset of the main array, then it print PASS, otherwise, it print FAIL instead.

What should I add to my if-else statement below to make it works?

a = [1,2,3,4,5]
b = [1,2]
c = [1,9]

# The Passing Scenario 

if (i in a for i in b):
 print "PASS"
else:
 print "FAIL"

# The Failing Scenario

if (i in a for i in c):
 print "PASS"
else:
 print "FAIL"

Could there be a list like d = [1,1,2], and if so, would you consider it a "subset" of a or not? — Tim Pietzcker
– Tim Pietzcker, Commented Mar 19, 2014 at 8:34
Tim, you are right.. You have pointed out the loophole on my code to validate a subset. If I am not mistaken, in math, the d is not a subset of a. But for my script, I will still consider it as the "subset" of a. As it won't affect my expected result. Thanks for your reminder :) — user3431399
– user3431399, Commented Mar 22, 2014 at 13:51

Jayanth Koushik · Accepted Answer · 2014-03-19 08:14:18Z

3

Use all.

# the passing scenario
if all(i in a for i in b):
    print 'PASS'
else:
    print 'FAIL'

# the failing scenario
if all(i in a for i in c):
    print 'PASS'
else:
    print 'FAIL'

answered Mar 19, 2014 at 8:14

Jayanth Koushik

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1 Comment

user3431399 Over a year ago

Thanks a lot, this solve my problem :D Although other answers are useful too, but I am limited to this if-else structure. Thanks everyone :D

Tim Pietzcker · Accepted Answer · 2014-03-19 08:33:52Z

2

With sets, it's easy:

>>> a = [1,2,3,4,5]
>>> b = [1,2]
>>> c = [1,9]
>>> set(b).issubset(set(a))
True
>>> set(c).issubset(set(a))
False

answered Mar 19, 2014 at 8:33

Tim Pietzcker

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Comments

thefourtheye · Accepted Answer · 2014-03-19 09:01:17Z

2

This can be done with the set operations like this

a    = [1,2,3,4,5]
b, c = [1,2],[1,9]

print set(b) <= set(a)
# True
print set(c) <= set(a)
# False

answered Mar 19, 2014 at 9:01

thefourtheye

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