函数类型
函数可以通过多种方式进行分类.在这里，我们根据它们采用的参数的数量和类型以及结果类型对它们进行了分类.功能可以是，
Atomic : 参数是原子的并产生原子结果
聚合 : 列表中的原子
统一(从列表中列出) : 扩展原子的概念，因为它们适用于列表.参数列表的计数等于结果列表的计数.
其他 : 如果该函数不是来自上述类别.
数学中的二进制运算在q中被称为二元函数 ;例如，"+".类似地，一元操作被称为 monadic函数;例如，"abs"或"floor".
常用函数
q
abs
q )abs -9.9/Absolute value，Negates -ve number&leaves non -ve number 9.9
all
q) all 4 5 0 -4 / Logical AND (numeric min), returns the minimum value0b
Max(&)，Min(|)和Not(！)
q) /And, Or, and Logical Negationq) 1b & 1b / And (Max)1bq) 1b|0b / Or (Min)1bq) not 1b /Logical Negate (Not)0b
asc
q)asc 1 3 5 7 -2 0 4 / Order list ascending, sorted list / in ascending order is returned`s#-2 0 1 3 4 5 7q)/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 grouped
avg
q)avg 3 4 5 6 7 / Return average of a list of numeric values5fq)/Create on trade tableq)trade:([]time:3?(.z.Z-200);sym:3?(`ibm`msft`apple);price:3?99.0;size:3?100)
by
q)/ by - Groups rows in a table at given symq)select sum price by sym from trade / find total price for each sym sym | price------ | -------- apple | 140.2165 ibm | 16.11385
cols
q)cols trade / Lists columns of a table`time`sym`price`size
count
q)count (til 9) / Count list, count the elements in a list and / return a single int value 9
port
q)\p 9999 / assign port numberq)/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 =`ibm
cut
q)/ cut - Allows a table or list to be cut at a certain pointq)(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"
删除
q)/delete - Delete rows/columns from a tableq)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 97
Distinct
q)/distinct - Returns the distinct element of a listq)distinct 1 2 3 2 3 4 5 2 1 3 / generate unique set of number1 2 3 4 5
enlist
q)/enlist - Creates one-item list.q)enlist 37,37q)type 37 / -ve type value-7hq)type enlist 37 / +ve type value7h
填充(^)
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 -53 4 100 100 -5q)`Hello^`jack`herry``john``jack`herry`Hello`john`Hello
填写
q)/fills - fills in nulls with the previous not null value.q)fills 1 0N 2 0N 0N 2 3 0N -5 0N1 1 2 2 2 2 3 3 -5 -5
第一个
q)/first - returns the first atom of a listq)first 1 3 34 5 31
翻转
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 97q)flip tradetime | 2009.06.18T06:04:42.919 2009.11.14T12:42:34.6532009.12.27T17:02:11.518sym | apple ibm appleprice | 72.05742 16.11385 68.15909size | 36 12 97
iasc
q)/iasc - 索引递增，返回相对于输入列表的升序排序列表的索引. q)iasc 5 4 0 3 4 9 2 3 1 4 0 5
Idesc
q)/idesc - 索引降序，返回相对于输入列表的下降排序列表q)idesc 0 1 3 4 3 2 1 0
in
q)/in - 在列表中，二元函数用于查询列表(右侧)关于其内容的列表. q)(2 4)in 1 2 3 10b
insert
q)/insert - Insert statement, upload new data into a table.q)insert[`trade;((.z.Z);`samsung;48.35;99)],3q)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 99
key
q)/key - 三个不同的函数，即生成+ ve整数，给出目录的内容或表/字典的键. 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 ..
lower
q)/lower - 转换为小写和floor q)lower("JoHn";`HERRY`SYM)"john"`herry`sym最大和最小(即|和&)
q)/Max and Min / a|b and a&bq)9|79q)9&55
null
q)/null - 如果是atom是一个null else参数列表中的0b q)null 1 3 3 0N $ b $ b 0001b
Peach
q)/peach - Parallel each, allows process across slavesq)foo peach list1 / function foo applied across the slaves named in list1'list1q)foo:{x+27}q)list1:(0 1 2 3 4)q)foo peach list1 / function foo applied across the slaves named in list127 28 29 30 31Prev
q)/prev - returns the previous element i.e. pushes list forwardsq)prev 0 1 3 4 5 70N 0 1 3 4 5
随机(？)
q)/random - syntax - n?list, gives random sequences of ints and floatsq)9?50 0 4 0 3 2 2 0 1q)3?9.90.2426823 1.674133 3.901671
Raze
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 3 430 0"hello"7 8134read0
q)/read0 - Read in a text fileq)read0 `:c:/q/README.txt / gives the contents of *.txt file
read1
q)/read1 - Read in a q data fileq)read1 `:c:/q/t10xff016200630b000500000073796d0074696d6500707269636…
反转
q)/reverse - Reverse a listq)reverse 2 30 29 1 3 44 3 1 29 30 2q)reverse "HelloWorld""dlroWolleH"
set
q)/set - set value of a variableq)`x set 9`xq)x9q)`:c:/q/test12 set trade`:c:/q/test12q)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 99
ssr
q)/ssr - String search and replace, syntax - ssr["string";searchstring;replaced-with]q)ssr["HelloWorld";"o";"O"]"HellOWOrld"
string
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 4941449 / number of seconds elapsed in a day at 11:30:49
system
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"
表
q)/tables - list all tablesq)tables ``s#`tab1`tab2`trade
Til
q)/til - Enumerateq)til 50 1 2 3 4
trim
q)/trim - Eliminate string spacesq)trim " John ""John"
v s
q)/vs - Vector from scaler , produces a vector quantity from a scaler quantityq)"|" 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 orderq)`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 36
xcol
q)/xcol - Renames columns of a tableq)`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 99
xcols
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 samsung
xdesc
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 12
xgroup
q)/xgroup - Creates nested tableq)`x xgroup ([]x:9 18 9 18 27 9 9;y:10 20 10 20 30 40)'lengthq)`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 | ,30
xkey
q)/xkey - Set key on tableq)`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 99
系统命令
系统命令控制 q 环境.它们具有以下形式 :
\ cmd [p] 其中p可以是可选的
下面讨论了一些流行的系统命令 :
\ a [namespace] - 列出给定命名空间中的表
q)/Tables in default namespaceq)\a,`tradeq)\a .o / table in .o namespace.,`TI
\b - 查看依赖关系
q)/ views/dependenciesq)a:: x+y / global assingmentq)b:: x+1q)\b`s#`a`b
\B - 待定视图/依赖项
q)/ Pending views/dependenciesq)a::x+1 / a depends on xq)\B / the dependency is pending' / the dependency is pendingq)\B`s#`a`bq)\b`s#`a`bq)b29q)a29q)\B`symbol$()
\ cd - 更改目录
q)/change directory, \cd [name]q)\cd"C:\\Users\\myaccount-raj"q)\cd ../new-accountq)\cd"C:\\Users\\new-account"
\d - 设置当前命名空间
q)/ sets current namespace \d [namespace]q)\d /default namespace'q)\d .o /change to .oq.o)\d`.oq.o)\d . / return to defaultq)key ` /lists namespaces other than .z`q`Q`h`j`oq)\d .john /change to non-existent namespaceq.john)\d`.johnq.john)\d .q)\d`.
\l - 从db加载文件或目录
q)/ Load file or directory, \lq)\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 - 端口号
q)/ assign port number, \pq)\p5001iq)\p 8888q)\p8888i
\\ - 从q控制台退出
\\ - exitExit form q.