foreach

Syntax

1q = foreach q generate expression as alias[, expression as alias ...];

The output column names are specified with the as keyword. The output data is ungrouped.

Using foreach with Ungrouped Data

When used with ungrouped data, the foreach statement maps the input rows to output rows. The number of rows remains the same.

Using foreach with Grouped Data

When used with grouped data, the foreach statement behaves differently than it does with ungrouped data.

Fields can be directly accessed only when the value is the same for all group members. For example, the fields that were used as the grouping keys have the same value for all group members. Otherwise, use aggregate functions to access the members of a group. The type of the column determines which aggregate functions you can use. For example, if the column type is numeric, you can use the sum() function.

Using foreach with a case Expression

Projected Field Names

Each field name in a projection must be unique and not have the name 'none'. Invalid field names throw an error.

1l = load "0Fabb000000002qCAA/0Fabb000000002WCAQ";
2r = load "0Fcyy000000002qCAA/0Fcyy000000002WCAQ";
3l = foreach l generate 'value'/'divisor' as 'value' , category as category;
4r = foreach r generate 'value'/'divisor' as 'value' , category as category;
5cg = cogroup l by category right, r by category;
6cg = foreach cg generate r.category as 'category', sum(r.value) as sumrval, sum(l.value) as sumrval;

1q = load "Products";
2q = group q by all;
3q = foreach q generate count() as 'none';
4q = limit q 2000;