Linking multiple python functions together

Question

Simple question on how to link (or string together) multiple functions that depend on each other. I have the following example function (in Jupyter):

### First function
def function_one():

    ## process one
    a = "one" + "two"
    print(a)

    ## process two
    b = "red" + "blue"
    print(b)

    ## process three
    c = "this" + "sucks"
    print(c)

    return a, b, c

### Second function
def function_two(a, b, c):

    ## process four
    d = a + b
    print(d)

    ## process five
    e = b + c
    print(e)

    ## process six
    f = a + c
    print(f)


    return d, e, f

### Third function
def function_three():

    g = a + b + c + d + e + f
    print(g)

    return g

### Calling functions
initial = function_one()
second = function_two(initial)
third = ... #I can't get past the following error to even link this function in

The first function works when called, but when I try to send that data downstream to the second function, I get this error:

onetwo
redblue
thissucks
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-10-7c5562b97c86> in <module>
      1 initial = function_one()
----> 2 second = function_two(initial)

TypeError: function_two() missing 2 required positional arguments: 'b' and 'c'

How do I remedy this?

Tomerikoo · Accepted Answer · 2020-04-20 06:18:56Z

4

When returning multiple objects, you are actually returning a tuple. Ex:

>>> def foo():
>>>     return 1, 2, 3

>>> type(foo())
<class 'tuple'>

So, right now the whole tuple is treated as argument a and hence b and c are missing. In order to pass that on as 3 separate arguments, you need to unpack that tuple:

initial = function_one()
second = function_two(*initial)
third = function_three(*initial, *second)

edited Apr 20, 2020 at 6:18

answered Apr 19, 2020 at 18:18

Tomerikoo

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1 Comment

papelr Over a year ago

This is... magical. Many thanks. I like the other answer, too, but I think yours is the simplest way. Thoughts?

Victor · Accepted Answer · 2020-04-19 18:38:09Z

2

Assign the return values to variables then pass it to the second function:

a, b, c = function_one()
function_two(a, b, c)

For your third function you need it to accept parameters as well

def function_three(a, b, c, d, e, f):
    g = a + b + c + d + e + f
    print(g)
    return g

Then putting it all together:

a, b, c = function_one()
d, e, f = function_two(a, b, c)
g = function_three(a, b, c, d, e, f)

edited Apr 19, 2020 at 18:38

answered Apr 19, 2020 at 18:15

Victor

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