Look at the definition of the function that returns the modulus of the number passed:
def abs(number):
if number >= 0:
return number
return -number
But you can write it more succinctly. To do this, there must be an expression to the right of return
, but if
is an instruction, not an expression. In Python there is a construction that works like if-else
but is considered an expression. It is called the tern operator - the only operator in Python that requires three operands:
def abs(number):
return number if number >= 0 else -number
The general pattern looks like this: `
Let's rewrite the initial version of get_type_of_sentence()
in the same way.
It was :
def get_type_of_sentence(sentence):
last_char = sentence[-1]
if last_char == '?':
return 'question'
return 'normal'
Became:
def get_type_of_sentence(sentence):
last_char = sentence[-1]
return 'question' if last_char == '?' else 'normal'
print(get_type_of_sentence('Hodor')) # => normal
print(get_type_of_sentence('Hodor?')) # => question
You can put a ternary operator into a ternary operator. But you shouldn't do it that way because such code is hard to read and debug.
Implement a function flip_flop()
that takes a string as input and, if that string is 'flip'
, returns the string 'flop'
. Otherwise, the function should return 'flip'
.
Examples of calls:
print(flip_flop('flip')) # => 'flop'
print(flip_flop('flop')) # => 'flip'
Try writing two versions of the function: with the usual if-else, and with the ternary operator.
If you've reached a deadlock it's time to ask your question in the «Discussions». How ask a question correctly:
Tests are designed so that they test the solution in different ways and against different data. Often the solution works with one kind of input data but doesn't work with others. Check the «Tests» tab to figure this out, you can find hints at the error output.
It's fine. 🙆 One task in programming can be solved in many different ways. If your code passed all tests, it complies with the task conditions.
In some rare cases, the solution may be adjusted to the tests, but this can be seen immediately.
It's hard to make educational materials that will suit everyone. We do our best but there is always something to improve. If you see a material that is not clear to you, describe the problem in “Discussions”. It will be great if you'll write unclear points in the question form. Usually, we need a few days for corrections.
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Your exercise will be checked with these tests:
1import index
2
3
4def test1():
5 assert index.flip_flop('flip') == 'flop'
6 assert index.flip_flop('flop') == 'flip'
7
Teacher's solution will be available in: