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Welcome to the Python-For-Q-Developers wiki!

Q is an excellent programming language that is widely used in the financial industry. Take a look here to get a quick overview of the language.

Below tables contain Python (including libraries Numpy and pandas) equivalent of a Q command. If you don't find something then probably there is no syntactic difference, for example, indexing a list is l[i] in both Python and Q.

General

	command	Q	Python	Q example	Python example	comment
QQ	performance
QQ	codes verbosity			([] a: 8 * til 4)	pd.DataFrame({'a': 8 * np.array(range(4))})
QQ	using [], (), {}	optional	mandatory
P	learning curve
PP	external libraries

Data types

	command	Q	Python	Q example	Python example	comment
	boolean constants	1b 0b	True False
	generic null	::	None
	typed null	0N, 0n, `, " ", etc	not supported
	infinite values	0W, -0W, 0w, etc.	math.inf
QQ	type symbol/category	`	not supported	`foo`bar		Python supports enum by class Enum, but it there you need to provide the list of values during object creation. In Q symbol `foo is represented by an integer and all Q process contain a symbol map. This is a flexible, memory efficient and convenient feature
P	complex number	not supported	j		3 + 4j

Data Structures

	command	Q	Python	Q example	Python example	comment
P	tuples	not supported	comma is the separator		3, 1.0, "hello"
	set	not supported	set		{2, 3 , 2 , 4}	Q's set functions e.g. inter, distinct serve set purpose
	tables	([] )	DataFrame in library pandas	([] col1: 1 2; col2: 3 4)	pd.DataFrame( {'col1': [1, 2], 'col2': [3, 4]})	In Q data structure table is part of the language
PP	Class	not supported	Class		class ClassName: ...

Operators

	command	Q	Python	Q example	Python example	comment
	assignment	:	=	a: 3	a= 3
	tuple unpacking	not supported	supported		x, y = 1, 2
	variable assignment inside an expression	supported	not supported	z*2+ (z: 3), 4
	comparison	=	==	3 = 5	3 == 5
	integer division	div	//	7 div 5	7 // 5
	non-integer division	%	/	10 % 3	10 / 3
	length of list/dictionary/table	count	len	count l	len(l)
Q	applying monadic function on a list	each	map	f each l	map(f, l)	You can omit keyword each in Q if f handles lists as input (most built in functions like neg, log, etc.) for example log li works fine. Python is not that flexible, try math.log(li)