Pipe character in Python
Question:
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?
Answers:
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.
It is a bitwise-or.
The documentation for all operators in Python can be found in the Index – Symbols page of the Python documentation.
This is also the union set operator
set([1,2]) | set([2,3])
This will result in set([1, 2, 3])
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
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?
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.
It is a bitwise-or.
The documentation for all operators in Python can be found in the Index – Symbols page of the Python documentation.
This is also the union set operator
set([1,2]) | set([2,3])
This will result in set([1, 2, 3])
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