default 'len' arg; more tests & validity checks

Author: HelenaLC

R/scalebar.R

@@ -27,11 +27,14 @@
 #' @importFrom ggplot2 annotate
 #' @importFrom methods is
 #' @export
-scalebar <- function(x, len, col="red", lwd=1, xrel=0.05, yrel=0.05) {
+scalebar <- function(x, len=NULL, col="red", lwd=1, xrel=0.05, yrel=0.05) {
     # validity
     if (!is(x, "SpatialDataArray")) 
         stop("'x' should be a 'SpatialDataArray' object, i.e., an",
             " image or label element from a 'SpatialData' object")
+    ok <- \(x) is.numeric(x) && is.finite(x) && length(x) == 1
+    if (!is.null(len)) stopifnot(ok(len), len > 0)
+    stopifnot(ok(xrel), ok(yrel))
 
     xi <- which(axes(x, "name") == "x")
     unit <- axes(x)[[xi]]$unit
@@ -42,6 +45,7 @@ scalebar <- function(x, len, col="red", lwd=1, xrel=0.05, yrel=0.05) {
         unit <- .unit_map[unit]
 
     wh <- .get_wh(x)
+    if (is.null(len)) len <- 0.05*diff(wh$w)
     if (xrel <= 0.5) {
         xmin <- diff(wh$w) * xrel + wh$w[1]
         xmax <- diff(wh$w) * xrel + wh$w[1] + len
@@ -58,7 +62,7 @@ scalebar <- function(x, len, col="red", lwd=1, xrel=0.05, yrel=0.05) {
     text <- annotate(
         geom="text", 
         x=(xmin+xmax)/2, y=y, 
-        color=col, label=paste0(len, unit),
-        vjust=ifelse(yrel > 0.5, 1.5, -0.5))
+        vjust=ifelse(yrel > 0.5, 1.5, -0.5),
+        color=col, label=paste0(round(len, 1), unit))
     return(list(line, text))
 }

man/scalebar.Rd

@@ -21,8 +21,22 @@ test_that("scalebar()", {
     y <- set_unit(image(x), "y")
     expect_error(scalebar(image(y), 1))
 
-    # valid specification
+    # invalid arguments
     y <- set_unit(image(x))
+    v <- c(c(1,1), Inf, TRUE, "")
+    for (. in v) {
+        expect_error(scalebar(y, len=.))
+        expect_error(scalebar(y, len=1, xrel=.))
+        expect_error(scalebar(y, len=1, yrel=.))
+    }
+    
+    # default 'len'
+    expect_silent(l <- scalebar(y, len=NULL))
+    p <- ggplot() + l
+    df <- layer_data(p, 1)
+    expect_equal(df$xend-df$x, 0.05*dim(y)[3])
+    
+    # valid arguments
     l <- scalebar(y, 
         len=len <- 5.1234, 
         xrel=xrel <- 0.05, 
@@ -42,4 +56,5 @@ test_that("scalebar()", {
     expect_equal(df$xend, dim(y)[3]*xrel+len)
     expect_equal(df$y, dim(y)[2]*(1-yrel))
     expect_equal(df$yend, df$y)
+    
 })