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Python Python Collections (Retired) Tuples Two-ples

2,097 Points

"When catching the values returned from a function, you have to have:" can u give me an example of this quiz?thx

I cant understand this quiz.

1 Answer

Chris Freeman
Chris Freeman
Treehouse Moderator 68,423 Points

From the quiz Two-ples:

"When catching the values returned from a function, you have to have:..."

"Catching", in this case, means assigning the returned values of a function call to a variable. Some functions return a single object, other functions may return multiple values. When returning multiple values, they are formed into a tuple.

It's an All or One rule. When more than one object is returned from a function, the receiving variables must be a single item, which will get assign the value of the tuple, or the exact number as the number number of objects returned so the return tuple can be properly unpacked.

Example, len() returns one object, an int, so exactly one variable can "catch" the output of this function:

length = len("this is  a string")

Trying to catch more, throws an error as int isn't an iterable collection:

In [24]: length = len("this is a string")

In [25]: length, width = len("this is  a string")
TypeError                                 Traceback (most recent call last)
<ipython-input-25-1043f5ccb688> in <module>()
----> 1 length, width = len("this is  a string")

TypeError: 'int' object is not iterable

In the example below cir_area returns two values as a tuple. The receiving variables need to be either one or two ("all").

$ ipython

In [1]: import math

In [2]: def cir_area(radius):
   ...:         """Return circumference and area of a circle given the radius."""
   ...:         cir = 2 * math.pi * radius
   ...:         area = math.pi * radius * radius
   ...:         return cir, area  # <-- (cir, area) also works here

In [3]: tup1 = cir_area(1)

In [4]: tup1
Out[4]: (6.283185307179586, 3.141592653589793)

In [5]: cur, area = cir_area(1)

In [6]: cur
Out[6]: 6.283185307179586

In [7]: area
Out[7]: 3.141592653589793

So back to the quiz:

Choose the correct answer below:

  • A The same number of variables as values
    • This works!
  • B Just a single variable
    • This works!
  • C Any number of variables up to the amount of return values (i.e. if 5 values come back, you can use 4 variables and the last will hold two values)
    • Not in Python
  • D Both A and B
    • The Correct Answer
2,097 Points

It helps me a lot.thx~