R Set Color, pch & cex of Specific Point in Graphic (Example Code)

This article illustrates how to modify color, shape, and size of points in a scatterplot in the R programming language.

Creation of Example Data

data(iris)                                 # Iris data set
head(iris)
#   Sepal.Length Sepal.Width Petal.Length Petal.Width Species
# 1          5.1         3.5          1.4         0.2  setosa
# 2          4.9         3.0          1.4         0.2  setosa
# 3          4.7         3.2          1.3         0.2  setosa
# 4          4.6         3.1          1.5         0.2  setosa
# 5          5.0         3.6          1.4         0.2  setosa
# 6          5.4         3.9          1.7         0.4  setosa

Example: Set Color of Specific Data Point in Graph Using ifelse() Function

plot(iris$Sepal.Length,                    # Draw plot without manual specifications
     iris$Sepal.Width)

r graph figure 1 r set color pch cex specific point graphic

iris_colors <- rep("black", nrow(iris))    # Change color of one point
iris_colors[10] <- "green"
iris_pch <- rep(1, nrow(iris))             # Change pch of one point
iris_pch[10] <- 17
iris_cex <- rep(1, nrow(iris))             # Change cex of one point
iris_cex[10] <- 3
plot(iris$Sepal.Length,                    # Draw plot with manual specifications
     iris$Sepal.Width,
     col = iris_colors,
     pch = iris_pch,
     cex = iris_cex)

r graph figure 2 r set color pch cex specific point graphic

Related Tutorials

You may find some related R programming tutorials on topics such as ggplot2, graphics in R, data objects, and plot legends in the list below.

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