Linguagem Q - Funções
Tipos de funções
As funções podem ser classificadas de várias maneiras. Aqui, nós os classificamos com base no número e tipo de argumento que assumem e no tipo de resultado. As funções podem ser,
Atomic - Onde os argumentos são atômicos e produzem resultados atômicos
Aggregate - átomo da lista
Uniform (list from list)- Estendeu o conceito de átomo conforme se aplica a listas. A contagem da lista de argumentos é igual à contagem da lista de resultados.
Other - se a função não pertencer à categoria acima.
Operações binárias em matemática são chamadas dyadic functionsem q; por exemplo, “+”. Da mesma forma, as operações unárias são chamadasmonadic functions; por exemplo, “abs” ou “chão”.
Funções frequentemente utilizadas
Existem algumas funções usadas com frequência em qprogramação. Aqui, nesta seção, veremos o uso de algumas funções populares -
abdômen
q) abs -9.9 / Absolute value, Negates -ve number & leaves non -ve number
9.9todos
q) all 4 5 0 -4 / Logical AND (numeric min), returns the minimum value
0bMáx (&), Mín (|) e Não (!)
q) /And, Or, and Logical Negation
q) 1b & 1b / And (Max)
1b
q) 1b|0b / Or (Min)
1b
q) not 1b /Logical Negate (Not)
0basc
q)asc 1 3 5 7 -2 0 4 / Order list ascending, sorted list
/ in ascending order i
s returned
`s#-2 0 1 3 4 5 7
q)/attr - gives the attributes of data, which describe how it's sorted.
`s denotes fully sorted, `u denotes unique and `p and `g are used to
refer to lists with repetition, with `p standing for parted and `g for groupedmédia
q)avg 3 4 5 6 7 / Return average of a list of numeric values
5f
q)/Create on trade table
q)trade:([]time:3?(.z.Z-200);sym:3?(`ibm`msft`apple);price:3?99.0;size:3?100)de
q)/ by - Groups rows in a table at given sym
q)select sum price by sym from trade / find total price for each sym
sym | price
------ | --------
apple | 140.2165
ibm | 16.11385cols
q)cols trade / Lists columns of a table
`time`sym`price`sizecontagem
q)count (til 9) / Count list, count the elements in a list and
/ return a single int value 9porta
q)\p 9999 / assign port number
q)/csv - This command allows queries in a browser to be exported to
excel by prefixing the query, such as http://localhost:9999/.csv?select from trade where sym =`ibmcortar
q)/ cut - Allows a table or list to be cut at a certain point
q)(1 3 5) cut "abcdefghijkl"
/ the argument is split at 1st, 3rd and 5th letter.
"bc"
"de"
"fghijkl"
q)5 cut "abcdefghijkl" / cut the right arg. Into 5 letters part
/ until its end.
"abcde"
"fghij"
"kl"Excluir
q)/delete - Delete rows/columns from a table
q)delete price from trade
time sym size
---------------------------------------
2009.06.18T06:04:42.919 apple 36
2009.11.14T12:42:34.653 ibm 12
2009.12.27T17:02:11.518 apple 97Distinto
q)/distinct - Returns the distinct element of a list
q)distinct 1 2 3 2 3 4 5 2 1 3 / generate unique set of number
1 2 3 4 5alistar
q)/enlist - Creates one-item list.
q)enlist 37
,37
q)type 37 / -ve type value
-7h
q)type enlist 37 / +ve type value
7hPreencher (^)
q)/fill - used with nulls. There are three functions for processing null values.
The dyadic function named fill replaces null values in the right argument with the atomic left argument.
q)100 ^ 3 4 0N 0N -5
3 4 100 100 -5
q)`Hello^`jack`herry``john`
`jack`herry`Hello`john`HelloPreenche
q)/fills - fills in nulls with the previous not null value.
q)fills 1 0N 2 0N 0N 2 3 0N -5 0N
1 1 2 2 2 2 3 3 -5 -5Primeiro
q)/first - returns the first atom of a list
q)first 1 3 34 5 3
1Giro
q)/flip - Monadic primitive that applies to lists and associations. It interchange the top two levels of its argument.
q)trade
time sym price size
------------------------------------------------------
2009.06.18T06:04:42.919 apple 72.05742 36
2009.11.14T12:42:34.653 ibm 16.11385 12
2009.12.27T17:02:11.518 apple 68.15909 97
q)flip trade
time | 2009.06.18T06:04:42.919 2009.11.14T12:42:34.653
2009.12.27T17:02:11.518
sym | apple ibm apple
price | 72.05742 16.11385 68.15909
size | 36 12 97iasc
q)/iasc - Index ascending, return the indices of the ascended sorted list relative to the input list.
q)iasc 5 4 0 3 4 9
2 3 1 4 0 5Idesc
q)/idesc - Index desceding, return the descended sorted list relative to the input list
q)idesc 0 1 3 4
3 2 1 0dentro
q)/in - In a list, dyadic function used to query list (on the right-handside) about their contents.
q)(2 4) in 1 2 3
10binserir
q)/insert - Insert statement, upload new data into a table.
q)insert[`trade;((.z.Z);`samsung;48.35;99)],3
q)trade
time sym price size
------------------------------------------------------
2009.06.18T06:04:42.919 apple 72.05742 36
2009.11.14T12:42:34.653 ibm 16.11385 12
2009.12.27T17:02:11.518 apple 68.15909 97
2015.04.06T10:03:36.738 samsung 48.35 99chave
q)/key - three different functions i.e. generate +ve integer number, gives content of a directory or key of a table/dictionary.
q)key 9
0 1 2 3 4 5 6 7 8
q)key `:c:
`$RECYCLE.BIN`Config.Msi`Documents and Settings`Drivers`Geojit`hiberfil.sys`I..mais baixo
q)/lower - Convert to lower case and floor
q)lower ("JoHn";`HERRY`SYM)
"john"
`herry`symMáx e Mín (ou seja | e &)
q)/Max and Min / a|b and a&b
q)9|7
9
q)9&5
5nulo
q)/null - return 1b if the atom is a null else 0b from the argument list
q)null 1 3 3 0N
0001bpêssego
q)/peach - Parallel each, allows process across slaves
q)foo peach list1 / function foo applied across the slaves named in list1
'list1
q)foo:{x+27}
q)list1:(0 1 2 3 4)
q)foo peach list1 / function foo applied across the slaves named in list1
27 28 29 30 31Anterior
q)/prev - returns the previous element i.e. pushes list forwards
q)prev 0 1 3 4 5 7
0N 0 1 3 4 5Aleatória( ?)
q)/random - syntax - n?list, gives random sequences of ints and floats
q)9?5
0 0 4 0 3 2 2 0 1
q)3?9.9
0.2426823 1.674133 3.901671Arrasar
q)/raze - Flattn a list of lists, removes a layer of indexing from a list of lists. for instance:
q)raze (( 12 3 4; 30 0);("hello";7 8); 1 3 4)
12 3 4
30 0
"hello"
7 8
1
3
4leia 0
q)/read0 - Read in a text file
q)read0 `:c:/q/README.txt / gives the contents of *.txt fileread1
q)/read1 - Read in a q data file
q)read1 `:c:/q/t1
0xff016200630b000500000073796d0074696d6500707269636…reverter
q)/reverse - Reverse a list
q)reverse 2 30 29 1 3 4
4 3 1 29 30 2
q)reverse "HelloWorld"
"dlroWolleH"conjunto
q)/set - set value of a variable
q)`x set 9
`x
q)x
9
q)`:c:/q/test12 set trade
`:c:/q/test12
q)get `:c:/q/test12
time sym price size
---------------------------------------------------------
2009.06.18T06:04:42.919 apple 72.05742 36
2009.11.14T12:42:34.653 ibm 16.11385 12
2009.12.27T17:02:11.518 apple 68.15909 97
2015.04.06T10:03:36.738 samsung 48.35 99
2015.04.06T10:03:47.540 samsung 48.35 99
2015.04.06T10:04:44.844 samsung 48.35 99ssr
q)/ssr - String search and replace, syntax - ssr["string";searchstring;replaced-with]
q)ssr["HelloWorld";"o";"O"]
"HellOWOrld"corda
q)/string - converts to string, converts all types to a string format.
q)string (1 2 3; `abc;"XYZ";0b)
(,"1";,"2";,"3")
"abc"
(,"X";,"Y";,"Z")
,"0"SV
q)/sv - Scalar from vector, performs different tasks dependent on its arguments.
It evaluates the base representation of numbers, which allows us to calculate the number of seconds in a month or convert a length from feet and inches to centimeters.
q)24 60 60 sv 11 30 49
41449 / number of seconds elapsed in a day at 11:30:49sistema
q)/system - allows a system command to be sent,
q)system "dir *.py"
" Volume in drive C is New Volume"
" Volume Serial Number is 8CD2-05B2"
""
" Directory of C:\\Users\\myaccount-raj"
""
"09/14/2014 06:32 PM 22 hello1.py"
" 1 File(s) 22 bytes"mesas
q)/tables - list all tables
q)tables `
`s#`tab1`tab2`tradeAté
q)/til - Enumerate
q)til 5
0 1 2 3 4aparar
q)/trim - Eliminate string spaces
q)trim " John "
"John"vs
q)/vs - Vector from scaler , produces a vector quantity from a scaler quantity
q)"|" vs "20150204|msft|20.45"
"20150204"
"msft"
"20.45"xasc
q)/xasc - Order table ascending, allows a table (right-hand argument) to be sorted such that (left-hand argument) is in ascending order
q)`price xasc trade
time sym price size
----------------------------------------------------------
2009.11.14T12:42:34.653 ibm 16.11385 12
2015.04.06T10:03:36.738 samsung 48.35 99
2015.04.06T10:03:47.540 samsung 48.35 99
2015.04.06T10:04:44.844 samsung 48.35 99
2009.12.27T17:02:11.518 apple 68.15909 97
2009.06.18T06:04:42.919 apple 72.05742 36xcol
q)/xcol - Renames columns of a table
q)`timeNew`symNew xcol trade
timeNew symNew price size
-------------------------------------------------------------
2009.06.18T06:04:42.919 apple 72.05742 36
2009.11.14T12:42:34.653 ibm 16.11385 12
2009.12.27T17:02:11.518 apple 68.15909 97
2015.04.06T10:03:36.738 samsung 48.35 99
2015.04.06T10:03:47.540 samsung 48.35 99
2015.04.06T10:04:44.844 samsung 48.35 99xcols
q)/xcols - Reorders the columns of a table,
q)`size`price xcols trade
size price time sym
-----------------------------------------------------------
36 72.05742 2009.06.18T06:04:42.919 apple
12 16.11385 2009.11.14T12:42:34.653 ibm
97 68.15909 2009.12.27T17:02:11.518 apple
99 48.35 2015.04.06T10:03:36.738 samsung
99 48.35 2015.04.06T10:03:47.540 samsung
99 48.35 2015.04.06T10:04:44.844 samsungxdesc
q)/xdesc - Order table descending, allows tables to be sorted such that the left-hand argument is in descending order.
q)`price xdesc trade
time sym price size
-----------------------------------------------------------
2009.06.18T06:04:42.919 apple 72.05742 36
2009.12.27T17:02:11.518 apple 68.15909 97
2015.04.06T10:03:36.738 samsung 48.35 99
2015.04.06T10:03:47.540 samsung 48.35 99
2015.04.06T10:04:44.844 samsung 48.35 99
2009.11.14T12:42:34.653 ibm 16.11385 12xgroup
q)/xgroup - Creates nested table
q)`x xgroup ([]x:9 18 9 18 27 9 9;y:10 20 10 20 30 40)
'length
q)`x xgroup ([]x:9 18 9 18 27 9 9;y:10 20 10 20 30 40 10)
x | y
---- | -----------
9 | 10 10 40 10
18 | 20 20
27 | ,30xkey
q)/xkey - Set key on table
q)`sym xkey trade
sym | time price size
--------- | -----------------------------------------------
apple | 2009.06.18T06:04:42.919 72.05742 36
ibm | 2009.11.14T12:42:34.653 16.11385 12
apple | 2009.12.27T17:02:11.518 68.15909 97
samsung | 2015.04.06T10:03:36.738 48.35 99
samsung | 2015.04.06T10:03:47.540 48.35 99
samsung | 2015.04.06T10:04:44.844 48.35 99Comandos do sistema
Os comandos do sistema controlam o qmeio Ambiente. Eles têm o seguinte formato -
\cmd [p] where p may be optionalAlguns dos comandos de sistema populares foram discutidos abaixo -
\ a [namespace] - lista as tabelas no namespace fornecido
q)/Tables in default namespace
q)\a
,`trade
q)\a .o / table in .o namespace.
,`TI\ b - Ver dependências
q)/ views/dependencies
q)a:: x+y / global assingment
q)b:: x+1
q)\b
`s#`a`b\ B - Vistas / dependências pendentes
q)/ Pending views/dependencies
q)a::x+1 / a depends on x
q)\B / the dependency is pending
' / the dependency is pending
q)\B
`s#`a`b
q)\b
`s#`a`b
q)b
29
q)a
29
q)\B
`symbol$()\ cd - Alterar diretório
q)/change directory, \cd [name]
q)\cd
"C:\\Users\\myaccount-raj"
q)\cd ../new-account
q)\cd
"C:\\Users\\new-account"\ d - define o namespace atual
q)/ sets current namespace \d [namespace]
q)\d /default namespace
'
q)\d .o /change to .o
q.o)\d
`.o
q.o)\d . / return to default
q)key ` /lists namespaces other than .z
`q`Q`h`j`o
q)\d .john /change to non-existent namespace
q.john)\d
`.john
q.john)\d .
q)\d
`.\ l - carrega arquivo ou diretório do banco de dados
q)/ Load file or directory, \l
q)\l test2.q / loading test2.q which is stored in current path.
ric | date ex openP closeP MCap
----------- | -------------------------------------------------
JPMORGAN | 2008.05.23 SENSEX 18.30185 17.16319 17876
HSBC | 2002.05.21 NIFTY 2.696749 16.58846 26559
JPMORGAN | 2006.09.07 NIFTY 14.15219 20.05624 14557
HSBC | 2010.10.11 SENSEX 7.394497 25.45859 29366
JPMORGAN | 2007.10.02 SENSEX 1.558085 25.61478 20390
ric | date ex openP closeP MCap
---------- | ------------------------------------------------
INFOSYS | 2003.10.30 DOW 21.2342 7.565652 2375
RELIANCE | 2004.08.12 DOW 12.34132 17.68381 4201
SBIN | 2008.02.14 DOW 1.830857 9.006485 15465
INFOSYS | 2009.06.11 HENSENG 19.47664 12.05208 11143
SBIN | 2010.07.05 DOW 18.55637 10.54082 15873\ p - número da porta
q)/ assign port number, \p
q)\p
5001i
q)\p 8888
q)\p
8888i\\ - Saia do q console
\\ - exit
Exit form q.