return value in Python

Question

I would like my function to return 1, 2, or 3 values, in regard to the value of bret and cret. How to do something more clever than this ? :

def myfunc (a, bret=False, cret=False):
  b=0
  c=0
  if bret and cret:
   return a,b,c
  elif bret and not cret:
   return a,b
  elif not bret and cret:
   return a,c
  else:
   return a

I'm not sure you want that. What if next question will be how to handle tuples with different lengths? — alko
– alko, Commented Dec 7, 2013 at 13:58
@alko Yup - especially for the two-form return where whether it's b or c is lost... — Jon Clements
– Jon Clements, Commented Dec 7, 2013 at 14:01
this is just an example @aro, in my real code b and c are more interesting values... — Basj
– Basj, Commented Dec 7, 2013 at 16:14

NPE · Accepted Answer · 2013-12-07 13:50:42Z

4

How about:

def myfunc(a, bret=False, cret=False):
   ...
   return (a,) + ((b,) if bret else ()) + ((c,) if cret else ())

answered Dec 7, 2013 at 13:50

NPE

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thefourtheye · Accepted Answer · 2013-12-07 13:46:25Z

3

def myfunc (a, bret=False, cret=False):
  b, c, ret = 0, 0, [a]
  if bret: ret.append(b)
  if cret: ret.append(c)
  return ret

answered Dec 7, 2013 at 13:46

thefourtheye

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Robert Kajic · Accepted Answer · 2013-12-07 14:00:14Z

2

def myfunc(a, bret=False, cret=False):
    return [v for v, ret in [(a, True), (0, bret), (0, cret)] if ret]

Take a moment to read about Python List Comprehensions. They are handy very often!

edited Dec 7, 2013 at 14:00

answered Dec 7, 2013 at 13:53

Robert Kajic

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Community · Accepted Answer · 2017-05-23 12:16:39Z

1

You might simply append your return values to a list or use yield. You can iterate over the result afterwards and do what you please. Here's an explanation to the yield-Keyword: What does the "yield" keyword do in Python?

edited May 23, 2017 at 12:16

CommunityBot

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answered Dec 7, 2013 at 13:48

TheWormKill

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ddetoni · Accepted Answer · 2013-12-07 14:03:03Z

1

You could return a list. Look:

def myfunc (a, bret=False, cret=False):

    list = []
    list.append(a)
    b=0
    c=0

    if bret:
        list.append(b)

    if cret:
        list.append(c)

    return list

Solve your question?

edited Dec 7, 2013 at 14:03

answered Dec 7, 2013 at 13:48

ddetoni

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2 Comments

Basj Over a year ago

no, the problem is not having a list. The problem is that this won't work anymore if 3 conditions, then there would be 2^3=8 cases to distinguish ! not beautiful ;)

NPE Over a year ago

This is equivalent to a much earlier solution posted by @thefourtheye (and I'd recommend against calling the variable list since this shadows the built-in function.)

Arovit · Accepted Answer · 2013-12-07 14:32:58Z

1

Please note if you have to return tuple (in your question it returns tuple) use this -

def myfunc(a, bret=False, cret=False):
    return tuple([a] + [0 for i in (bret, cret) if i])

edited Dec 7, 2013 at 14:32

answered Dec 7, 2013 at 13:56

Arovit

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2 Comments

NPE Over a year ago

This returns bret/cret instead of b/c.

Arovit Over a year ago

Return value is always - a, a,0 or a,0,0

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