String formatting issue when using a function

Question

I have what I believe to be an embarrassingly simple problem, but three hours of googling and checking stackoverflow have not helped.

Let's say I have a very simple piece of code:

def secret_formula(started):
  jelly_beans = started*500
  jars = jelly_beans/1000
  crates = jars/100
  return jelly_beans,jars,crates

start_point = 10000

print("We'd have {} beans, {} jars, and {} crates.".format(secret_formula(start_point)))

What happens is I get the "IndexError: tuple index out of range". So I just print the secret_formula function to see what it looks like, and it looks like this:

(5000000, 5000.0, 50.0)

Basically, it is treating the output as one 'thing' (I am still very new, sorry if my language is not correct). My question is, why does it treat it like this and how do I make it pass the three outputs (jelly_beans, jars, and crates) so that it formats the string properly?

Thanks!

Sylvain Defresne · Accepted Answer · 2012-01-29 23:33:22Z

1

The format function of the string take a variable number of argument. The secret_formula function is returning a tuple. You want to convert that to a list of arguments. This is done using the following syntax:

print("We'd have {} beans, {} jars, and {} crates.".format(*secret_formula(start_point)))

The important par is the * character. It tell that you want to convert the following iterable into a list of argument to pass to the function.

answered Jan 29, 2012 at 23:33

Sylvain Defresne

45.2k12 gold badges81 silver badges88 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

popwat Over a year ago

Thanks! I tried to use the * but I was putting it in the wrong place so I gave up.

Collectives™ on Stack Overflow

String formatting issue when using a function

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related