adambard/learnxinyminutes-docs
1
1
Fork 0
mirror of https://github.com/adambard/learnxinyminutes-docs.git synced 2025-01-09 00:23:02 +03:00
Code Issues Projects Releases Wiki Activity

series of fixes and improvements (#2563)

Browse Source
This commit is contained in:
Matt Doherty 2016-11-10 12:47:02 +00:00 committed by ven
parent 94787745d5
commit 0804650a9a
1 changed files with 21 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

39
kdb+.html.markdown
View File

@ -256,7 +256,7 @@ l / => 5 2 3 4
/ Lists can also be used for indexing and indexed assignment / Lists can also be used for indexing and indexed assignment
l[1 3] / => 2 4 l[1 3] / => 2 4
l[1 3]: 1 3 l[1 3]: 1 3
l / => 1 1 3 3 l / => 5 1 3 3
/ Lists can be untyped/mixed type / Lists can be untyped/mixed type
l:(1;2;`hi) l:(1;2;`hi)
@ -290,6 +290,7 @@ last 1 2 3 / => 3
/ Take (#), drop (_) and find (?) are also useful working with lists / Take (#), drop (_) and find (?) are also useful working with lists
l:1 2 3 4 5 6 7 8 9 l:1 2 3 4 5 6 7 8 9
l:1+til 9 / til is a useful shortcut for generating ranges
/ take the first 5 elements / take the first 5 elements
5#l / => 1 2 3 4 5 5#l / => 1 2 3 4 5
/ drop the first 5 / drop the first 5
@ -297,7 +298,7 @@ l:1 2 3 4 5 6 7 8 9
/ take the last 5 / take the last 5
-5#l / => 5 6 7 8 9 -5#l / => 5 6 7 8 9
/ drop the last 5 / drop the last 5
-5_l / => 1 2 3 4 5 -5_l / => 1 2 3 4
/ find the first occurance of 4 / find the first occurance of 4
l?4 / => 3 l?4 / => 3
l[3] / => 4 l[3] / => 4
@ -397,7 +398,7 @@ k!t
/ => id| c1 c2 c3 / => id| c1 c2 c3
/ => --| -------- / => --| --------
/ => 1 | 1 4 7 / => 1 | 1 4 7
/ => 2 | 2 5 8 / => 2 | 3 5 8
/ => 3 | 3 6 9 / => 3 | 3 6 9
/ We can also use this shortcut for defining keyed tables / We can also use this shortcut for defining keyed tables
@ -455,7 +456,7 @@ f[2] / => 4
/ however using a dictionary as a single argument can overcome this / however using a dictionary as a single argument can overcome this
/ allows for optional arguments or differing functionality / allows for optional arguments or differing functionality
d:`arg1`arg2`arg3!(1.0;2;"my function argument") d:`arg1`arg2`arg3!(1.0;2;"my function argument")
{x[`arg1]+x[`arg2]}[d] / => 3.0 {x[`arg1]+x[`arg2]}[d] / => 3f
/ Functions in q see the global scope / Functions in q see the global scope
a:1 a:1
@ -464,6 +465,7 @@ a:1
/ However local scope obscures this / However local scope obscures this
a:1 a:1
{a:2;:a}[] / => 2 {a:2;:a}[] / => 2
a / => 1
/ Functions cannot see nested scopes (only local and global) / Functions cannot see nested scopes (only local and global)
{local:1;{:local}[]}[] / throws error as local is not defined in inner function {local:1;{:local}[]}[] / throws error as local is not defined in inner function
@ -494,11 +496,11 @@ t:([]name:`Arthur`Thomas`Polly;age:35 32 52;height:180 175 160;sex:`m`m`f)
/ equivalent of SELECT * FROM t / equivalent of SELECT * FROM t
select from t / (must be lower case, and the wildcard is not necessary) select from t / (must be lower case, and the wildcard is not necessary)
/ => name age height / => name age height sex
/ => ----------------- / => ---------------------
/ => Arthur 35 180 / => Arthur 35 180 m
/ => Thomas 32 175 / => Thomas 32 175 m
/ => Polly 52 160 / => Polly 52 160 f
/ Select specific columns / Select specific columns
select name,age from t select name,age from t
@ -523,6 +525,7 @@ select name, feet:floor height*0.032, inches:12*(height*0.032) mod 1 from t
/ => ------------------ / => ------------------
/ => Arthur 5 9.12 / => Arthur 5 9.12
/ => Thomas 5 7.2 / => Thomas 5 7.2
/ => Polly 5 1.44
/ Including custom functions / Including custom functions
select name, growth:{[h;a]h%a}[height;age] from t select name, growth:{[h;a]h%a}[height;age] from t
@ -534,18 +537,18 @@ select name, growth:{[h;a]h%a}[height;age] from t
/ The where clause can contain multiple statements separated by commas / The where clause can contain multiple statements separated by commas
select from t where age>33,height>175 select from t where age>33,height>175
/ => name age height / => name age height sex
/ => ----------------- / => ---------------------
/ => Arthur 35 180 / => Arthur 35 180 m
/ The where statements are executed sequentially (not the same as logical AND) / The where statements are executed sequentially (not the same as logical AND)
select from t where age<40,height=min height select from t where age<40,height=min height
/ => name age height / => name age height sex
/ => ----------------- / => ---------------------
/ => Thomas 32 175 / => Thomas 32 175 m
select from t where (age<40)&(height=min height) select from t where (age<40)&(height=min height)
/ => name age height / => name age height sex
/ => --------------- / => -------------------
/ The by clause falls between select and from / The by clause falls between select and from
/ and is equivalent to SQL's GROUP BY / and is equivalent to SQL's GROUP BY
@ -585,7 +588,7 @@ t
/ => Polly 52 160 f / => Polly 52 160 f
/ Insert however is in place, it takes a table name, and new data / Insert however is in place, it takes a table name, and new data
`t insert (`John;25;178;`m) `t insert (`John;25;178;`m) / => ,3
t t
/ => name age height sex / => name age height sex
/ => --------------------- / => ---------------------