R/read.bathy.R

In ericpante/marmap: Import, Plot and Analyze Bathymetric and Topographic Data

read.bathy <- function(xyz, header=FALSE, sep=",", ...){

### xyz: three-column table with longitude (x), latitude (y) and depth (z) (no default)
### header: whether this table has a row of column names (default = FALSE)
### sep: character separating columns, (default=",")

	bath <- read.table(xyz, header = header, sep = sep, ...)
	bath <- bath[order(bath[, 2], bath[, 1], decreasing = FALSE), ]

    lat <- unique(bath[, 2]) ; bcol <- length(lat)
    lon <- unique(bath[, 1]) ; brow <- length(lon)

	if ((bcol*brow) == nrow(bath)) {
		mat <- matrix(bath[, 3], nrow = brow, ncol = bcol, byrow = FALSE, dimnames = list(lon, lat))
		} else {
			colnames(bath) <- paste("V",1:3,sep="")
			mat <- reshape2::acast(bath, V1~V2, value.var="V3")
		}
		
    ordered.mat <- check.bathy(mat)
    class(ordered.mat) <- "bathy"
    return(ordered.mat)
	
}