R corrplot - coloring based on correlation values

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R corrplot - coloring based on correlation values

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#1 by (5 votes)

3

I have a binary dataframe (53115 rows; 520 columns) and I want to make a correlation chart. I want to color the correlation values in red if they are greater than or equal to 0.95, otherwise blue.

correl = abs(round(cor(bin_mat),2))

pdf("corrplot.pdf", width = 200, height = 200)  

a = corrplot(correl, order = "hclust", addCoef.col = "black", number.cex=0.8, cl.lim = c(0,1), col=c(rep("deepskyblue",19) ,"red"))  

dev.off()

I was able to get the graph but in many cases I get a wrong coloring (see graph below in value 0.91).

datafile: file

How can I correct this problem to have a correct color?

r

asked by anonymous 03.10.2018 / 03:08

1 answer

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score 5 · Answer 1

The problem is how the col option, when custom palettes are used, works together with cl.lim . The package documentation talks about it. See what happens with and without cl.lim . I'm using the mtcars base, included in the R, for example, and using cutoff at 0.8 for easy viewing:

correl <- cor(mtcars)

library(corrplot)

par(mfrow = c(1,2))

  corrplot(abs(correl),
    addCoef.col = "black",
    cl.lim = c(0, 1),
    col = c(rep("deepskyblue", 9) ,"red") 
  )  

  corrplot(abs(correl),
    addCoef.col = "black",
    col = c(rep("deepskyblue", 9) ,"red") 
  )

Correlationsoccurinacontinuumbetween-1and1;corrplotmapscolorstothisrange(removingthesignfromcorrelationsissimplyabadidea)andcannotadjustthecaptionwhenthepaletteiscustomized.

Furthermore,unlikethevalueofp,whereitmatterswhetheritisaboveorbelowathreshold,theintensityofthecorrelationindexvalueisimportant.Socorrplotwasnotdonethinkingaboutqualitativescales.

Onewaytosolveyourcasebykeepingthesignsistosimplygeneratethecolorstoworkinthe-1:1range,withthedivisionsyouwant.Thecaptionwillbeuseless,socutit:

corrplot(correl,addCoef.col="black",
  col = c("red", rep("deepskyblue", 8) ,"red"),
  cl.pos = 'n'
)

Just change the value to rep for your case (38). But the advice is to use a continuous palette.