如何从单个记录中求和多个元素 [英] How to sum multiple elements from single record

问题描述

我有桌子trade:([]time:`time$(); sym:`symbol$(); price:`float$(); size:`long$()) 与1000条记录，例如10个独特的符号.我想对每个符号的前4个价格求和.

I have table trade:([]time:`time$(); sym:`symbol$(); price:`float$(); size:`long$()) with e.g. 1000 records, with e.g. 10 unique syms. I want to sum the first 4 prices for each sym.

我的代码如下:

priceTable: select price by sym from trade;
amountTable: select count price by sym from trade;
amountTable: `sym`amount xcol amountTable;
resultTable: amountTable ij priceTable;

所以我的新表如下:resultTable

sym    | amount price  
-------| --------------------------------------------------------------
instr0 | 106    179.2208 153.7646 155.2658 143.8163 107.9041 195.521 ..

命令结果:res: select sum price from resultTable where i = 1:

price                                                                 
..
----------------------------------
14.71512 153.2244 154.1642 196.5744

现在，当我想对元素求和时，会收到:sum res

Now, when I want to sum elements I receive: sum res

price| 14.71512 153.2244 154.1642 196.5744 170.6052 61.26522 45.70606
46.9057..

当我要计算res中的元素时:count res

When I want to count elements in res: count res

1

我假设res是具有多个值的单个记录，如何对所有这些值求和，或者如何首先求和?

I assume that res is a single record with many values, how can I sum all of those values, or how can I sum first for?

推荐答案

您可以使用"each"在每一行上求和:

You can use "each" to run the sum on each row:

select sum each price from res

或者如果您想在resoultTable上运行:

Or if you want to run on resoultTable:

select sum each price from resoultTable

要对每行的前四个价格求和，请使用二进位的each-right:

To sum the first four prices for each row, use a dyadic each-right:

select sum each 4#/:price from resoultTable

或者您可以一步很简单地完成所有这些操作:

Or you could do all of this very easily, in one step:

select COUNT:count i, SUM:sum price, SUM4:sum 4#price by sym from trade

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