`g_lstpkg(G;S;O;X)`

Returns a list value for each group, in the specified order. (Available as of version 15.21)

Function type

Vector only

Syntax

g_lstpkg(G;S;O;X)

Input

Argument	Type	Description
`G`	any	A space- or comma-separated list of column names Rows are in the same group if their values for all of the columns listed in `G` are the same. If `G` is omitted, all rows are considered to be in the same group. If any of the columns listed in `G` contain N/A, the N/A value is considered a valid grouping value.
`S`	integer	The name of a column in which every row evaluates to a 1 or 0, which determines whether or not that row is selected to be included in the calculation If `S` is omitted, all rows will be considered by the function (subject to any prior row selections). If any of the values in `S` are neither 1 nor 0, an error is returned.
`O`	integer	A space- or comma-separated list of column names that determine the row order within a particular group If `O` is omitted, the order is the current display order of the table. If any of the values in `O` are N/A, an error is returned.
`X`	package	The `X` argument must be a package value

Return Value

For every row in each group defined by G and ordered by O (and for those rows where S=1, if specified), g_lstpkg returns a list value for each group specified by G for the package X.

Note: g_lstpkg(G;S;O;X) works like g_lst(G;S;O;X), except that X must be a package, and g_lstpkg returns a transposed version of what g_lst returns.

Example

In the following example, we use r_mappkg(C;S;X) to create a package out of each row of table data in pub.demo.retail.item. Then, we use g_lstpkg(G;S;O;X) to return a list of items grouped by transaction ID. Finally, we convert that list of records (objects) into JSON format.

First, we create a record column and use r_mappkg(C;S;X) to create a package value for each row in the table:

<willbe name="record" value="r_mappkg(;;rcv_)"/>

Then, we create a group column and use g_lstpkg(G;S;O;X) to create a list out of the package in the record column, grouped by transid:

<willbe name="group" value="g_lstpkg(transid;;;record)"/>

Since each value for a transaction ID will be the same, we can select only the first record of each transaction ID, as follows:

<sel value="g_first1(transid;;)"/>

Then, we can use enjson(V;O) to convert the list in the group column into JSON:

<willbe name="json" value="enjson(group;)"/>

And let's display only those columns of interest to us:

<colord cols="transid,json"/>

If you display the full details of the json column, you will see a JSON representation of a package of equal-length lists, with each key corresponding to the values from the same key in the package arguments.