diff --git a/R-package/DESCRIPTION b/R-package/DESCRIPTION
index f36e34274..6594954f3 100644
--- a/R-package/DESCRIPTION
+++ b/R-package/DESCRIPTION
@@ -20,11 +20,12 @@ BugReports: https://github.com/dmlc/xgboost/issues
 VignetteBuilder: knitr
 Suggests:
     knitr,
-    ggplot2 (>= 1.0.0),
+    ggplot2 (>= 1.0.1),
     DiagrammeR (>= 0.8.1),
     Ckmeans.1d.dp (>= 3.3.1),
     vcd (>= 1.3),
-    testthat
+    testthat,
+    igraph (>= 1.0.1)
 Depends:
     R (>= 2.10)
 Imports:
diff --git a/R-package/demo/xgb.plot.multi.tree.R b/R-package/demo/xgb.plot.multi.tree.R
deleted file mode 100644
index feb7e667e..000000000
--- a/R-package/demo/xgb.plot.multi.tree.R
+++ /dev/null
@@ -1,64 +0,0 @@
-library(stringr)
-library(data.table)
-library(xgboost)
-
-
-data(agaricus.train, package='xgboost')
-
-#Both dataset are list with two items, a sparse matrix and labels
-#(labels = outcome column which will be learned).
-#Each column of the sparse Matrix is a feature in one hot encoding format.
-train <- agaricus.train
-
-bst <- xgboost(data = train$data, label = train$label, max.depth = 2,
-               eta = 1, nthread = 2, nround = 4, objective = "binary:logistic")
-
-#agaricus.test$data@Dimnames[[2]] represents the column names of the sparse matrix.
-tree.matrix <- xgb.model.dt.tree(agaricus.train$data@Dimnames[[2]], model = bst)
-
-
-# first number of the path represents the tree, then the following numbers are related to the path to follow
-
-# root init
-root.nodes <- tree.matrix[str_detect(ID, "\\d+-0"), ID]
-tree.matrix[ID == root.nodes, Abs.Position:=root.nodes]
-
-precedent.nodes <- root.nodes
-
-while(tree.matrix[,sum(is.na(Abs.Position))] > 0) {
-  yes.row.nodes <- tree.matrix[Abs.Position %in% precedent.nodes & !is.na(Yes)]
-  no.row.nodes <- tree.matrix[Abs.Position %in% precedent.nodes & !is.na(No)]
-  yes.nodes.abs.pos <- yes.row.nodes[, Abs.Position] %>% paste0("_0")
-  no.nodes.abs.pos <- no.row.nodes[, Abs.Position] %>% paste0("_1")
-  
-  tree.matrix[ID == yes.row.nodes[, Yes], Abs.Position := yes.nodes.abs.pos]
-  tree.matrix[ID == no.row.nodes[, No], Abs.Position := no.nodes.abs.pos]
-  precedent.nodes <- c(yes.nodes.abs.pos, no.nodes.abs.pos)
-}
-
-tree.matrix[!is.na(Yes),Yes:= paste0(Abs.Position, "_0")]
-tree.matrix[!is.na(No),No:= paste0(Abs.Position, "_1")]
-tree.matrix[,ID:= Abs.Position]
-
-tree.matrix[,Abs.Position:=substr(Abs.Position, nchar(Tree)+2, nchar(Abs.Position))]
-keepN <- 3
-tree.matrix <- tree.matrix[,sum(Quality),by = .(Abs.Position, Feature)][order(-V1)][,.(paste0(Feature[1:min(length(Feature), keepN)], " (", V1[1:min(length(V1), keepN)], ")") %>% paste0(collapse = "\n")), by=Abs.Position]
-
-tree.matrix[Feature!="Leaf" ,yesPath:= paste(ID,"(", Feature, "<br/>Cover: ", Cover, "<br/>Gain: ", Quality, ")-->|< ", Split, "|", Yes, ">", Yes.Feature, "]", sep = "")]
-
-tree.matrix[Feature!="Leaf" ,noPath:= paste(ID,"(", Feature, ")-->|>= ", Split, "|", No, ">", No.Feature, "]", sep = "")]
-
-tree.matrix[, Yes:= Abs.Position %>% paste0("_0")][, No:= Abs.Position %>% paste0("_1")]
-
-CSSstyle <- "classDef greenNode fill:#A2EB86, stroke:#04C4AB, stroke-width:2px\nclassDef redNode fill:#FFA070, stroke:#FF5E5E, stroke-width:2px"  
-
-
-yes <- tree.matrix[Feature!="Leaf", c(Yes)] %>% paste(collapse = ",") %>% paste("class ", ., " greenNode", sep = "")
-
-no <- tree.matrix[Feature!="Leaf", c(No)] %>% paste(collapse = ",") %>% paste("class ", ., " redNode", sep = "")
-
-path <- tree.matrix[Feature!="Leaf", c(yesPath, noPath)] %>% .[order(.)] %>% paste(sep = "", collapse = "\n") %>% paste("graph LR", .,collapse = "", sep = "\n") %>% paste(CSSstyle, yes, no, sep = "\n")
-DiagrammeR::mermaid(path)
-
-# path <- "graph LR;0-0-0(spore-print-color=green)-->|>= 2.00001|0-0-0-1>Leaf"
-# setnames(tree.matrix, old = c("ID", "Yes", "No"), c("nodes", "edge_from", "edge_to"))