KDB Table Pivot逆向工程问题

Question

在 KDB 中，我有一个简单的表，我正在尝试对其进行透视。使用https://code.kx.com/q/kb/pivoting-tables/我还是迷路了。我是 KDB 的新手。我有一张 table

t:([]sym:`IBM`FB`TESLA`IBM;exchange:`A`A`B`B;OB_p1:4#100.1;OB_p2:100.2 100.2 100.3 100.4;OB_p3:100.5 100.6 100.7 100.8;OB_p4:100.8 100.8 100.8 100.9)

sym     exchange  OB_p1  OB_p2  OB_p3   OB_p4
IBM     A         100.1  100.2  100.5   100.8
FB      A         100.1  100.2  100.6   100.8
TESLA   B         100.1  100.3  100.7   100.8
IBM     B         100.1  100.4  100.8   100.9

我正在尝试创建下表:

exchange OB    IBM   FB  TESLA 
A        OB_1  
A        OB_1
B        OB_1

我想知道是否有人可以协助完成这项任务？我已经尝试过 https://code.kx.com/q/kb/pivoting-tables/ 上的数据透视表推荐没有运气

Answer 1

示例表:

t:flip `sym`exchange`OB_p1`OB_p2`OB_p3`OB_p4!flip (
    (`IBM;`A;100.1;100.2;100.5;100.8);
    (`FB;`A;100.1;100.2;100.6;100.8);
    (`TESLA;`B;100.1;100.3;100.7;100.8);
    (`IBM;`B;100.1;100.4;100.8;100.9))

给予:

sym   exchange OB_p1 OB_p2 OB_p3 OB_p4
--------------------------------------
IBM   A        100.1 100.2 100.5 100.8
FB    A        100.1 100.2 100.6 100.8
TESLA B        100.1 100.3 100.7 100.8
IBM   B        100.1 100.4 100.8 100.9

unpivot 函数取自 https://gist.github.com/rianoc/a14b832f12908c4785e2297995db1e76

unpivot:{[tab;baseCols;pivotCols;kCol;vCol] 
 base:?[tab;();0b;{x!x}(),baseCols];
 newCols:{[k;v;t;p] flip (k;v)!(count[t]#p;t p)}[kCol;vCol;tab] each pivotCols;
 baseCols xasc raze {[b;n] b,'n}[base] each newCols
 }

调用:

t:unpivot[t;`sym`exchange;`OB_p1`OB_p2`OB_p3`OB_p4;`OB;`val]

给予:

sym   exchange OB    val  
--------------------------
FB    A        OB_p1 100.1
FB    A        OB_p2 100.2
FB    A        OB_p3 100.6
FB    A        OB_p4 100.8
IBM   A        OB_p1 100.1
IBM   A        OB_p2 100.2
IBM   A        OB_p3 100.5
IBM   A        OB_p4 100.8
IBM   B        OB_p1 100.1
IBM   B        OB_p2 100.4
IBM   B        OB_p3 100.8
IBM   B        OB_p4 100.9
TESLA B        OB_p1 100.1
TESLA B        OB_p2 100.3
TESLA B        OB_p3 100.7
TESLA B        OB_p4 100.8

piv 函数取自 https://code.kx.com/q/kb/pivoting-tables/

命名透视列时，此用例简化了链接中的

f

piv:{[t;k;p;v;f;g]
 v:(),v;
 G:group flip k!(t:.Q.v t)k;
 F:group flip p!t p;
 count[k]!g[k;P;C]xcols 0!key[G]!flip(C:f[v]P:flip value flip key F)!raze
  {[i;j;k;x;y]
   a:count[x]#x 0N;
   a[y]:x y;
   b:count[x]#0b;
   b[y]:1b;
   c:a i;
   c[k]:first'[a[j]@'where'[b j]];
   c}[I[;0];I J;J:where 1<>count'[I:value G]]/:\:[t v;value F]}

f:{[v;P]P[;0]} 
g:{[k;P;c]k,(raze/)flip flip each 5 cut'10 cut raze reverse 10 cut asc c}

调用:

piv[t;`exchange`OB;(),`sym;(),`val;f;g]

给予:

exchange OB   | FB    IBM   TESLA
--------------| -----------------
A        OB_p1| 100.1 100.1      
A        OB_p2| 100.2 100.2      
A        OB_p3| 100.6 100.5      
A        OB_p4| 100.8 100.8      
B        OB_p1|       100.1 100.1
B        OB_p2|       100.4 100.3
B        OB_p3|       100.8 100.7
B        OB_p4|       100.9 100.8