R/join_by_id.R

In mengluchu/APMtools: statistical air pollution mapping tools

#' Join variables with coordinates to the destination file by ID, so it requires an ID file with coordinates
#' @param IDfile sp or dataframe with coordinate and ID that Oliver uses
#' @param coordinatefile sp or datafrme with coordinate and variables values (air quality measurements) but no ID
#' @param file2merge dataframe to merge to, i.e. file with all the variables
#' @param varname the name of the variable in the coordinatefile to merge
#' @return a dataframe
#' @export
#' @examples
#' \donttest{join_by_id(IDfile= testoaq, coordinatefile=meanoaq, file2merge = merged, varname='day_mean')
#' require(sf)
#' require(maptools)
#' require(sp)
#' meanoaq = read.csv('q_day.csv') #locations and values
#' testoaq = read.csv('openaqmorethan1000_ch_locations.csv') # ID with locaitons
#' join_by_id(IDfile= testoaq, coordinatefile=d, file2merge = merged, varname='value', newname = 'day_value')}
join_by_id = function(IDfile, coordinatefile, file2merge = merged, varname = "value", newname) {
    if (is.data.frame(IDfile)) {
        coordinates(IDfile) = ~longitude + latitude
        warning("coordinate variable names should be exactly longitude and latitude")
    }
    if (is.data.frame(coordinatefile)) {
        coordinates(coordinatefile) = ~longitude + latitude
        warning("coordinate variable names should be exactly longitude and latitude")
    }

    testoverra = over(IDfile, coordinatefile)
    testsp = data.frame(spCbind(IDfile, testoverra))

    Stestsf = testsp[, c("X", varname)]
    names(Stestsf) = c("X", newname)

    mergedfile = merge(file2merge, Stestsf, by.x = "ID", by.y = "X", all.x = TRUE)
    return(mergedfile)
}