# Calculation - First

(Redirected from Calculate - First)

Extracts the first rows or columns in selected outputs

Extracts the first rows or columns (e.g. first 2 rows or first 5 columns) of selected summary tables, crosstabs or R vectors, R matrices, R arrays, R data frames, R lists or R tables, and saves them as a new R outputs. Alternatively, if the input data is labeled with dates or date-times, this feature is able to extract the first date or time periods in the data, e.g., first 3 years, first week, first 10 hours etc. A new R output is created for each selected output and this R output contains controls which allow settings to be specified (see Options section below).

## Examples

Shown below is the output from extracting the first 3 rows from a summary table of a Pick One questionNominal variable set for Age:

Shown below is the output from extracting the first 1 calendar month from an R vector that is labeled with dates starting from November 20, 2020. If instead a non-calendar period was specified (see Calendar periods in the Options section below), all dates up to and including December 19, 2020 would be extracted.

## Options

Data The data output from which rows or columns are to be extracted. This can be a summary table, crosstab or R vector, R matrix, R array, R data frame, R list or R table.

Unit Specify whether to extract first rows, columns, or date-time periods (year, quarter, month, week, day, hour, minute, second) from the data. If the data is one-dimensional, "Row" should be selected for this option.

Keep The number of units (specified in the previous control) to extract.

Calendar periods Whether to consider calendar periods. When calendar periods are considered, a year is counted as the 12-month period from January to December; a quarter is one of the following 3-month periods: January-March, April-June, July-September, October-December; a month is the period from the first to last day in the 12 months in the calendar; a week is the 7 day period from Sunday to Saturday; a day is the 24 hour period from midnight to midnight; and hours, minutes and seconds are the fixed periods as indicated on a clock. For example, if the first 2 calendar years are to be kept and the earliest date in the data is Nov 6, 2020, all data labeled in 2020 and 2021 will be kept. When non-calendar periods are considered instead, all periods are compared against a reference date-time, which is the earliest date-time in the labels. For periods that do not have a fixed duration, i.e., years, quarters and months, a period is defined using the day and month of the reference date-time. For example if the reference date-time is Nov 6 2020 12:34:56pm, and the first 2 years of data are to be kept, all data up to (but not including) Nov 6 2022 12:34:56pm would be retained. If the reference date-time falls on a day for which the corresponding end-of-period date-time does not exist, then all actual date-times up to this mock end-of-period date-time are considered. For example, 1 month from March 31 12:34:56pm includes all date-times up to and including April 30.

## Code

includeWeb('Table Selection Functions');
selectFromTables('First rows');