Pipe character in Python

I see a "pipe" character (|) used in a function call:

res = c1.create(go, come, swim, "", startTime, endTime, "OK", ax|bx)

What is the meaning of the pipe in ax|bx?

This is also the union set operator

set([1,2]) | set([2,3])

This will result in set([1, 2, 3])

It is a bitwise OR of integers. For example, if one or both of ax or bx are 1, this evaluates to 1, otherwise to 0. It also works on other integers, for example 15 | 128 = 143, i.e. 00001111 | 10000000 = 10001111 in binary.

Yep, all answers above are correct.

Although you could find more exotic use cases for "|", if it is an overloaded operator used by a class, for example,

https://github.com/twitter/pycascading/wiki#pycascading

input = flow.source(Hfs(TextLine(), 'input_file.txt'))
output = flow.sink(Hfs(TextDelimited(), 'output_folder'))

input | map_replace(split_words, 'word') | group_by('word', native.count()) | output

In this specific use case pipe "|" operator can be better thought as a unix pipe operator. But I agree, bit-wise operator and union set operator are much more common use cases for "|" in Python.

In Python 3.9 - PEP 584 - Add Union Operators To dict in the section titled Specification, the operator is explained. The pipe was enhanced to merge (union) dictionaries.

>>> d = {'spam': 1, 'eggs': 2, 'cheese': 3}
>>> e = {'cheese': 4, 'nut': 5}
>>> d | e
{'spam': 1, 'eggs': 2, 'cheese': 4, 'nut': 5} # comment 1
>>> e | d
{'cheese': 3, 'nut': 5, 'spam': 1, 'eggs': 2} # comment 2

comment 1 If a key appears in both operands, the last-seen value (i.e. that from the right-hand operand) wins --> 'cheese': 4 instead of 'cheese': 3

comment 2 cheese appears twice, the second value is selected so d[cheese]=3

http://docs.python.org/reference/expressions.html#binary-bitwise-operations">Bitwise OR.

It is a bitwise-or.

The documentation for all operators in Python can be found in the Index - Symbols page of the Python documentation.