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Python Python Collections (Retired) Dictionaries Membership

Posted by Ryan Carson
Ryan Carson
23,287 Points

Can't solve counts.py Code Challenge

I'm getting the error message "Bummer! Expected 1, got 1" error message on my Code Challenge.

The Challenge is:

Write a function named members that takes two arguments, a dictionary and a list of keys. Return a count of how many of the keys are in the dictionary.

Here's my code:

def members(dictionary, keys):
  count = 0
  for key in dictionary:
    if key in keys:
      count =+ 1
  return count

2 Answers

Milo Winningham
seal-mask
.a{fill-rule:evenodd;}techdegree
Milo Winningham
Web Development Techdegree Student 3,317 Points
Milo Winningham
.a{fill-rule:evenodd;}techdegree
Milo Winningham
Web Development Techdegree Student 3,317 Points

count =+ 1 will set the count to the number +1. To increment the count variable you'd need to use count += 1. We should get a better error message for this though.

Jose Luis Lopez
Jose Luis Lopez
19,179 Points
Jose Luis Lopez
Jose Luis Lopez
19,179 Points

def members(dictionary, keys): count = 0 for key in dictionary: if key in keys: count =+2 return count

This work for me

Dan Badertscher
Dan Badertscher
5,327 Points
Dan Badertscher
Dan Badertscher
5,327 Points

This worked for me as well. Can you please explain why we are using "count =+2" instead of "count=+1"?

Yu Cao
Yu Cao
2,414 Points
Yu Cao
Yu Cao
2,414 Points

You are doing it wrong. Because the example that was used to check for this question happened to yield 2. So when you use count=+2, it only returns a hardcoded number of 2. When you use it for another example that has 3 keys in the list, you are still getting 2 and that will be wrong. Milo's comment is correct and you should use count += 1 to increment your count by 1 for each key in the list. Your answer is definitely wrong and just happened to be the correct answer for this particular answer.