Add check so that only distbegin and distend OR distance are supplied

Also amended tests to comply with this.
Reference #144

R/checkdata.R

@@ -25,10 +25,16 @@ checkdata <- function(data, region.table=NULL, sample.table=NULL,
     }
   }
 
+
+  # Make sure that the user has only specified either distance or distend / distbegin (need to do this check first as then Distance creates the distance column)
+  if(!is.null(data$distance) && !is.null(data$distbegin) && !is.null(data$distend)){
+    stop("You can only specify either a 'distance' column or 'distbegin' and 'distend' columns in your data.", call. = FALSE)
+  }
+
   # make sure that the data are in the right format first
   if(is.null(data$distance)){
     if(is.null(data$distend) & is.null(data$distbegin)){
-      stop("Your data must (at least) have a column called 'distance' or 'distbegin' and 'distend'!")
+      stop("Your data must (at least) have a column called 'distance' or 'distbegin' and 'distend'!", call. = FALSE)
     }else{
       data$distance <- (data$distend + data$distbegin)/2
     }

tests/testthat/test_ds.R

@@ -176,6 +176,8 @@ test_that("Truncation is handled",{
 
   # largest bin
   bin.data <- create_bins(egdata,c(0,1,2,3,3.8))
+  # Remove distance column
+  bin.data <- subset(bin.data, select = -c(distance))
   expect_equal(suppressMessages(ds(bin.data, key="hn",
                                    order=0))$ddf$meta.data$width, 3.8)
 
@@ -226,8 +228,7 @@ test_that("cutpoints work with flatfile", {
                     convert_units = units,  cutpoints = c(seq(0,8,1)),
                     formula = ~Region.Label)
 
-  pigs2 <- data.frame(distance  = (distbegin+distend)/2,
-                      distbegin = distbegin,
+  pigs2 <- data.frame(distbegin = distbegin,
                       distend   = distend,
                       Region.Label = pigs$Region.Label,
                       Area         = 0)