popEpi (version 0.4.12)

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

Description

Convenience function for using 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. 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")