merge_difdate: Merge Difdate

In wfmueller29/SLAM: SLAM - Functions for Longitduinal Datasets

Merge Difdate

Description

Functions that merges two dataframes that have measurements at different dates. It matches the closest measurement in data2 before, after, or before or after the measurement in data1. If a threshold is specified, it will ensure the closest measurement falls within that threshold or it will set it to missing.

Usage

merge_difdate(
  data1,
  data2,
  id,
  date,
  threshold = c(weeks = Inf),
  vars = NULL,
  where = "both",
  suffixes = c(".1", ".2"),
  clean_vars = TRUE
)

Arguments

data1	a dataframe that has the ids and dates of measurement that will serve as a reference for matching with data2
data2	a dataframe that has the ids and dates of measurement we would like to match with the reference id's and dates and data1
id	either a character string, or a character vector of length 2. If the id variable in data1 and data2 have the same name, id is a character string. If the id variable of data1 and data2 are different, then id is a character vector, with the first value being the id variable of data1 and the second being the id variable for data2.
date	either a character string, or a character vector of length 2. If the date variable in data1 and data2 have the same name, date is a character string. If the date variable of data1 and data2 are different, then date is a character vector, with the first value being the date variable of data1 and the second being the date variable for data2.
threshold	a named numeric value that provides the difference in time between measurements allowed. The units of the threshold are specified by the name of threshold. Valid units are can be found in the difftime units argument.
vars	optional character vector that provides the variable names for which this should be applied over. If specified, for each variable specified by var, only non-missing values will be considered when merging with the closest measurement date.
where	a character string that specifies where to look for the closest observation in data2 relative to data1. "before" means that merge_difdate will look before the reference observation in data1. "after" means the same except after. "both" means that merge_difdate will match using observations on either side of the reference observation in data1.
suffixes	specifies the suffix for non-unique variables between the two dataframes. However, even if the date and id variables are unique between the two dataframes, they will be assigned a suffix.
clean_vars	default is true. Will return all data1 columns and remove any duplicate columns from data2 with the exception of the date column.

Value

a dataframe where each unique subject and date measurement in data1 is matched with the closest dated measurement for that subject in data2.

Author(s)

William Mueller, Jorge Martinez Romero

wfmueller29/SLAM documentation built on April 5, 2025, 5:09 a.m.