Institutions: Global |ALU | Ekurhuleni Libraries | Joburg Libraries | Tshwane Libraries | TUT | UCT | UJ | UNISA | UP | UZ | Wits | Invest in Zim

MathsGee is Zero-Rated (You do not need data to access) on: Telkom |Dimension Data | Rain | MWEB

1 like 0 dislike
77 views
How will you create scatterplot matrices in R language?
| 77 views

## 1 Answer

0 like 0 dislike
Best answer
1. Launch RStudio as described here: Running RStudio and setting up your working directory

2. Prepare your data as described here: Best practices for preparing your data and save it in an external .txt tab or .csv files

3. Import your data into R

Data

iris data is used in the following examples. iris data set gives the measurements in centimeters of the variables sepal length and width, and petal length and width, respectively, for 50 flowers from each of 3 species of iris. The species are Iris setosa, versicolor, and virginica.

head(iris)

R base scatter plot matrices: pairs()

• Basic plots:
pairs(iris[,1:4], pch = 19)

• Show only upper panel:
pairs(iris[,1:4], pch = 19, lower.panel = NULL)

• Color points by groups (species)
my_cols <- c("#00AFBB", "#E7B800", "#FC4E07")
pairs(iris[,1:4], pch = 19,  cex = 0.5,
col = my_cols[iris$Species], lower.panel=NULL) • Add correlations on the lower panels: The size of the text is proportional to the correlations. # Correlation panel panel.cor <- function(x, y){ usr <- par("usr"); on.exit(par(usr)) par(usr = c(0, 1, 0, 1)) r <- round(cor(x, y), digits=2) txt <- paste0("R = ", r) cex.cor <- 0.8/strwidth(txt) text(0.5, 0.5, txt, cex = cex.cor * r) } # Customize upper panel upper.panel<-function(x, y){ points(x,y, pch = 19, col = my_cols[iris$Species])
}
# Create the plots
pairs(iris[,1:4],
lower.panel = panel.cor,
upper.panel = upper.panel)

• Add correlations on the scatter plots:
# Customize upper panel
upper.panel<-function(x, y){
points(x,y, pch=19, col=c("red", "green3", "blue")[iris\$Species])
r <- round(cor(x, y), digits=2)
txt <- paste0("R = ", r)
usr <- par("usr"); on.exit(par(usr))
par(usr = c(0, 1, 0, 1))
text(0.5, 0.9, txt)
}
pairs(iris[,1:4], lower.panel = NULL,
upper.panel = upper.panel)

Use the R package psych

The function pairs.panels [in psych package] can be also used to create a scatter plot of matrices, with bivariate scatter plots below the diagonal, histograms on the diagonal, and the Pearson correlation above the diagonal.

library(psych)
pairs.panels(iris[,-5],
method = "pearson", # correlation method
hist.col = "#00AFBB",
density = TRUE,  # show density plots
ellipses = TRUE # show correlation ellipses
)

by Diamond (60,788 points)

0 like 0 dislike
0 answers
0 like 0 dislike
0 answers
0 like 0 dislike
0 answers
1 like 0 dislike
1 answer
0 like 0 dislike
0 answers