popEpi (version 0.4.14)

cast_simple: Cast data.table/data.frame from long format to wide format

Description

Convenience function for using [data.table::dcast.data.table]; inputs are character strings (names of variables) instead of a formula.

Usage

cast_simple(data = NULL, columns = NULL, rows = NULL, values = NULL)

Value

A data.table just like [data.table::dcast].

Arguments

data

a data.table or data.frame

columns

a character string vector; the (unique combinations of the) levels of these variable will be different rows

rows

a character string vector; the (unique combinations of the) levels of these variable will be different columns

values

a character string; the variable which will be represented on rows and columns as specified by columns and rows

Author

Matti Rantanen, Joonas Miettinen

Details

This function is just a small interface for dcast / dcast.data.table and less flexible than the originals.

Note that all data.table objects are also data.frame objects, but that each have their own dcast method. [data.table::dcast.data.table] is faster.

If any values in value.vars need to be aggregated, they are aggregated using sum. See ?dcast.

Examples

library("data.table")
## e.g. silly counts from a long-format table to a wide format
test <- data.table::copy(popEpi::sire)
test$dg_y <- year(test$dg_date)
test$ex_y <- year(test$ex_date)
tab <- ltable(test, c("dg_y","ex_y"))
cast_simple(tab, columns='dg_y', rows="ex_y", values="obs")