New function to visualise the LexRank graph

R/visualiseLexRank.R

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+## Objective is to visualise LexRank plot
+## I find it helpful to inspect the plot
+## And colour the nodes that represent the sentences that were selected
+
+
+## inputs
+### similDf <- the output df of the sentenceSimil function
+### threshold <- user input on the threshold. edges are formed when weight is above the threshold
+
+
+## output 
+### plot of the sentences as nodes and edges when similarity is above the set threshold
+
+library(tidyr)
+library(dplyr)
+library(igraph)
+library(lexRankr)
+
+
+text = c("Testing the system. Second sentence for you.",
+         "System testing the tidy documents df.",
+         "Documents will be parsed and lexranked.",
+         "Plot the lexrank graph. See the lexrank graph connections.",
+         "Complete test of lexrank graph.")
+sentTokList <- sentenceTokenParse(text)
+sentDf <- sentTokList$sentences
+tokenDf <- sentTokList$tokens
+similDf <- sentenceSimil(sentenceId = tokenDf$sentenceId, 
+                         token = tokenDf$token, 
+                         docId = tokenDf$docId)
+topNSents <- lexRankFromSimil(s1 = similDf$sent1, 
+                              s2 = similDf$sent2, 
+                              simil = similDf$similVal,
+                              n=1)
+
+
+## if given the selected sentences in the format as per the output of lexRankFromSimil
+## function to visualise the nodes of the sentences
+visualiseLexRank <- function(similDf, 
+                             threshold = 0.2,
+                             selectedSents = NULL){
+    edges <- data.frame(s1 = similDf$sent1, 
+                        s2 = similDf$sent2, 
+                        weight = similDf$similVal, 
+                        stringsAsFactors = FALSE)
+    edges <- edges[edges$weight > threshold, c("s1", "s2")]
+    sentGraph <- igraph::graph_from_data_frame(edges, directed = FALSE)
+
+    ## if selectedSents is provided
+    ## the selected sentences will be coded blue
+    ## and the other nodes yellow
+    if(!is.null(selectedSents)){
+        V(sentGraph)$select <-  as.character(selectedSents$value[match(V(sentGraph)$name,selectedSents$sentenceId)]) 
+        V(sentGraph)$color <- "yellow" # default node color is yellow
+        V(sentGraph)$color[!is.na(V(sentGraph)$select)] <- "blue" # selected sentences in blue
+    }
+    plot.igraph(sentGraph)
+}
+
+
+## test the functions
+visualiseLexRank(similDf)
+visualiseLexRank(similDf, selectedSents = topNSents)