Basic scatterplot in base R



A very basic scatterplot built with base R and the plot() function. Explanation and code provided.

Scatter section Data to Viz

Most basic scatterplot


The plot() function of R allows to build a scatterplot. Both numeric variables of the input dataframe must be specified in the x and y argument.

Customizations


Here is a description of the most common customization:

  • cex: circle size
  • xlim and ylim: limits of the X and Y axis
  • pch: shape of markers. See all here.
  • xlab and ylab: X and Y axis labels
  • col: marker color
  • main: chart title

Map the marker color to a categorical variable


# the iris dataset is provided by R natively

# Create a color palette
library(paletteer)
colors = paletteer_c("scico::berlin", n=3)

# Scatterplot with categoric color scale
plot(
  x = iris$Petal.Length,
  y = iris$Petal.Width,
  bg = colors[ unclass(iris$Species) ],
  cex = 3,
  pch=21
)

Map the marker color to a numeric variable


# the iris dataset is provided by R natively

# Create a color palette
library(paletteer)
nColor <- 20
colors = paletteer_c("viridis::inferno", n=nColor)

# Transform the numeric variable in bins
rank <- as.factor( as.numeric( cut(iris$Petal.Width, nColor)))

# Scatterplot with color gradient
plot(
  x = iris$Petal.Length, 
  y = iris$Petal.Width,
  bg = colors[ rank ],
  cex = 3,
  pch=21
)

Related chart types


Scatter
Heatmap
Correlogram
Bubble
Connected scatter
Density 2d



Contact

This document is a work by Yan Holtz. Any feedback is highly encouraged. You can fill an issue on Github, drop me a message on Twitter, or send an email pasting yan.holtz.data with gmail.com.

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