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======ASCII Scatterplots in R====== <code c scat.R> scat <- function(y, x, cols=50, rows=20, pch="*") { #make an ASCII scatterplot on a rows X cols grid #pch is the ASCII character plotted #check arguments y <- as.numeric(y) if(missing(x)) x <- 1:length(y) else x <- as.numeric(x) if(length(y) != length(x)) stop("lengths of y and x differ") rows <- as.numeric(rows) cols <- as.numeric(cols) if(rows < 1 || cols < 1) stop("rows and cols must be > 1") if(nchar(pch)!=1) stop("pch must be exactly one character") #map the y and x values to rows and cols #FIXME values in y or x could be NA or NaN #FIXME division by zero when max(y)-min(y) == 0 #FIXME any better way to do this? ymap <- round((y-min(y))/(max(y)-min(y))*(rows-1)) xmap <- round((x-min(x))/(max(x)-min(x))*(cols-1)) #sort the mapped values so that the are drawn in #left-to-right top-to-bottom order, because thats #how they will be printed, unique because we can #only print one character in a cell bitmap <- unique(cbind(ymap,xmap)[order(-ymap, xmap),]) #initialize cursor positions: top-left row <- rows - 1 col <- 0 #print top border cat(" ", rep("_", cols+4), "\n| ", sep="") cat(rep(" ", cols), " |\n| ", sep="") #print pch at each position in bitmap for(bit in 1:nrow(bitmap)) { #skip to row of next bit while(bitmap[bit,1] != row) { if(cols-col > 0) cat(rep(" ", cols-col), sep="") cat(" |\n| ") row <- row - 1 col <- 0 } #skip to col of next bit if(bitmap[bit,2]-col > 0) cat(rep(" ", bitmap[bit,2]-col), sep="") #print the character cat(pch) col <- bitmap[bit, 2] + 1 } #finish the last line and bottom border if(cols-col > 0) cat(rep(" ", cols-col), sep="") cat(" |\n|", rep("_", cols+4), "|\n", sep="") invisible(bitmap) } </code>
