joyn (version 0.2.4)

check_match_type: Check match type consistency

Description

This function checks if the match type chosen by the user is consistent with the data.
(Match type must be one of the valid types: "1:1", "1:m", "m:1", "m:m")

Usage

check_match_type(x, y, by, match_type, verbose = getOption("joyn.verbose"))

Value

character vector from split_match_type

Arguments

x, y

data tables. y is coerced to a data.table if it isn't one already.

by

A vector of shared column names in x and y to merge on. This defaults to the shared key columns between the two tables. If y has no key columns, this defaults to the key of x.

match_type

character: one of "m:m", "m:1", "1:m", "1:1". Default is "1:1" since this the most restrictive. However, following Stata's recommendation, it is better to be explicit and use any of the other three match types (See details in match types sections).

Examples

if (FALSE) {
# Consistent match type
x1 = data.frame(
       id = c(1L, 1L, 2L, 3L, NA_integer_),
       t  = c(1L, 2L, 1L, 2L, NA_integer_),
       x  = 11:15)
y1 = data.frame(id = 1:2,
                y  = c(11L, 15L))
joyn:::check_match_type(x = x1, y=y1, by="id", match_type = "m:1")

# Inconsistent match type
joyn:::check_match_type(x = x1, y=y1, by="id", match_type = "1:1")
}