read_network(): bugfix check directionality. Warning rather that error.

Fixes #41

DESCRIPTION

 Package: mapMCDA
 Title: Produce an epidemiological risk map by weighting multiple risk
         factors
-Version: 0.4.50
+Version: 0.4.51
 Date: 2020-04-29
 Authors@R: c( person("Andrea", "Apolloni", email =
         "andrea.apolloni@cirad.fr", role = c("ctb"), comment = "Animal

R/network.R

@@ -147,11 +147,11 @@ must be respected:",
   
   ## Check graph is directed
   ## At least one edge contains a reciprocal
-  if( !any(duplicated(rbind(dat[, 1:2], dat[, 2:1]))) ) {
-    stop(
-      "All the links are unidirectional.\n",
-      "If you are sure that the network is directed, add at least one
-      reciprocal link with a weight of 0 and proceed."
+  if( !any(duplicated(rbind(dat[, 1:2], setNames(dat[, 2:1], names(dat[, 1:2]))))) ) {
+    warning(
+      "All the links are unidirectional which seems implausible.\n",
+      "Note that mapMCDA works only with directed networks.\n",
+      "If you are sure that the network is directed, you can proceed."
     )
   }
   

tests/testthat/test-load.R

@@ -65,14 +65,14 @@ test_that("Interpret network data", {
   tf <- tempfile()
   write.csv(td, tf, row.names = FALSE)
   
-  n1 <- expect_error(read_network(tf), NA)
+  n1 <- expect_error(suppressWarnings(read_network(tf)), NA)
   expect_s3_class(n1, "igraph")
 
   ## Test data with ";" field separator and "," decimal separator
   tf2 <- tempfile()
   writeLines(gsub(",", ";", readLines(tf)), file(tf2))
   writeLines(gsub("\\.", ",", readLines(tf2)), file(tf2))
-  n2 <- expect_error(read_network(tf2), NA)
+  n2 <- expect_error(suppressWarnings(read_network(tf2)), NA)
   expect_s3_class(n2, "igraph")
 
   # all.equal(n1, n2)
@@ -93,6 +93,27 @@ test_that("Informative errors for incorrectly formatted network data", {
   )
 })
 
+test_that("Warning about undirected graphs", {
+  
+  ## Single movement from A to B
+  df <- data.frame(
+    orig = "A",
+    dest = "B",
+    olon = 1,
+    olat = 1,
+    dlon = 2,
+    dlat = 2,
+    stringsAsFactors = FALSE
+  )
+  
+  tf <- tempfile(fileext = ".csv")
+  write.csv(df, file = tf, row.names = FALSE)
+  expect_warning(
+    read_network(tf),
+    "All the links are unidirectional"
+  )
+})
+
 test_that("Informative errors for inconsistent network data", {
   
   ## Same locations with different coordinates
@@ -110,7 +131,7 @@ test_that("Informative errors for inconsistent network data", {
   tf <- tempfile(fileext = ".csv")
   write.csv(df, file = tf, row.names = FALSE)
   expect_error(
-    read_network(tf),
+    suppressWarnings(read_network(tf)),
     "Inconsistent coordinates"
   )
   
@@ -131,7 +152,7 @@ test_that("Informative errors for inconsistent network data", {
   tf <- tempfile(fileext = ".csv")
   write.csv(df, file = tf, row.names = FALSE)
   expect_error(
-    read_network(tf),
+    suppressWarnings(read_network(tf)),
     "Detected different locations with the same coordinates."
   )