Fix r interaction constraints (#5543)

* Unify the parsing code.

* Cleanup.

R-package/tests/testthat/test_interaction_constraints.R

@@ -14,25 +14,42 @@ test_that("interaction constraints for regression", {
   bst <- xgboost(data = train, label = y, max_depth = 3,
                  eta = 0.1, nthread = 2, nrounds = 100, verbose = 0,
                  interaction_constraints = list(c(0,1)))
-  
+
   # Set all observations to have the same x3 values then increment
   #  by the same amount
-	preds <- lapply(c(1,2,3), function(x){
-		tmat <- matrix(c(x1,x2,rep(x,1000)), ncol=3)
-		return(predict(bst, tmat))
-	})
+  preds <- lapply(c(1,2,3), function(x){
+    tmat <- matrix(c(x1,x2,rep(x,1000)), ncol=3)
+    return(predict(bst, tmat))
+  })
 
   # Check incrementing x3 has the same effect on all observations
   #   since x3 is constrained to be independent of x1 and x2
   #   and all observations start off from the same x3 value
-	diff1 <- preds[[2]] - preds[[1]]
-	test1 <- all(abs(diff1 - diff1[1]) < 1e-4)
-	
-	diff2 <- preds[[3]] - preds[[2]]
-	test2 <- all(abs(diff2 - diff2[1]) < 1e-4)
-	
+  diff1 <- preds[[2]] - preds[[1]]
+  test1 <- all(abs(diff1 - diff1[1]) < 1e-4)
+
+  diff2 <- preds[[3]] - preds[[2]]
+  test2 <- all(abs(diff2 - diff2[1]) < 1e-4)
+
   expect_true({
     test1 & test2
   }, "Interaction Contraint Satisfied")
-  
+})
+
+test_that("interaction constraints scientific representation", {
+  rows <- 10
+  ## When number exceeds 1e5, R paste function uses scientific representation.
+  ## See: https://github.com/dmlc/xgboost/issues/5179
+  cols <- 1e5+10
+
+  d <- matrix(rexp(rows, rate=.1), nrow=rows, ncol=cols)
+  y <- rnorm(rows)
+
+  dtrain <- xgb.DMatrix(data=d, info = list(label=y))
+  inc <- list(c(seq.int(from = 0, to = cols, by = 1)))
+
+  with_inc <- xgb.train(data=dtrain, tree_method='hist',
+                        interaction_constraints=inc, nrounds=10)
+  without_inc <- xgb.train(data=dtrain, tree_method='hist', nrounds=10)
+  expect_equal(xgb.save.raw(with_inc), xgb.save.raw(without_inc))
 })