Select transformation
{ select: ... }
select
is used to get rid of undesired columns. Some datasets might have a lot of
columns, and using select, the irrelevant ones can be thrown away. This will
reduce memory usage and improve performance a bit.
Instructions
Type | Description | Result |
---|---|---|
String | Name of column | All other columns except this one are thrown away |
Array | Names of columns | All other columns except these are thrown away |
Usage
The select
transformation's instructions can be passed as a single String,
or as an Array of Strings. When passing a single String, the String must be the
name of a column. This will result in selecting a single column:
<vgg-data
:data="{ a: [1, 2, 3, 4], b: [5, 6, 7, 8] }"
:transform="{ select: 'a' }"
>
<!-- Data scope: { a: [1, 2, 3, 4] } -->
</vgg-data>
Passing an Array of column names will result in selecting those columns:
<vgg-data
:data="{ a: [1, 2, 3, 4], b: [5, 6, 7, 8], c: [9, 10, 11, 12] }"
:transform="{ select: ['a', 'b'] }"
>
<!-- Data scope: { a: [1, 2, 3, 4], b: [5, 6, 7, 8] } -->
</vgg-data>