CODEWITHSUNDEEP
pythonpython-3.x
Alan Coromano
Alan Coromano

Reputation: 26048

Parentheses in Python's method calling

Here is a simple Python code

for item in sorted(frequency, key=frequency.get, reverse=True)[:20]:
  print(item, frequency[item])

However, if call frequency.get() instead of frequency.get, it will give me the error of "get expected at least 1 arguments, got 0"

I came from Ruby. In Ruby get and get() would be exactly the same. Is it not the same in Python?

For example, here is http://www.tutorialspoint.com/python/dictionary_get.htm the description of get() and not get. What is get?

Upvotes: 0

Views: 168

Answers (1)

David Robinson
David Robinson

Reputation: 78660

frequency.get describes the method itself, while frequency.get() actually calls the method (and incorrectly gives it no arguments). You are right that this is different than Ruby.

For example, consider:

frequency = {"a": 1, "b": 2}
x = frequency.get("a")

In this case, x is equal to 1. However, if we did:

x = frequency.get

x would now be a function. For instance:

print x("a")
# 1
print x("b")
# 2

This function is what you are passing to sorted.

Upvotes: 9

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