Visualization with Base R

R has always included a package of graphics functions, so you do not need to install anything extra. These “Base Graphics” are:

• plot() as a universal tool,
• hist() for histograms,
• boxplot() for box plots,
• barplot() for bar charts.

These functions have several advantages—you do not need any extra packages, they are fast and directly available, and they are sufficient for initial exploratory steps. At the same time, however, they are somewhat less flexible than other packages we will get to know, and some customizations are not entirely user-friendly. Nevertheless, R base is sufficient for many everyday tasks!

Simple chart types

Histogram

Syntax: hist(x, main=…, xlab=…, col=…)

• main = title
• xlab, ylab = axis labels
• col = bar color

Result: An overview of the distribution. You can see where most of the data lie.

x <- c(2,3,3,4,6,7,9,9,10)

hist(x, 

     main="Histogramm von X", 

     xlab="Werte", 

     col="skyblue")

Box plot

Syntax: boxplot(x, main=…, horizontal=TRUE/FALSE, col=…)

Shows the median (thick line inside the box), Q1/Q3 (box edges), whiskers, and, where applicable, outliers as points.

boxplot(x, 

        main="Boxplot von X", 

        col="orange", 

        horizontal=TRUE)

Bar chart (barplot)

Typically used for categorical data.

# Frequenzberechnung einer kategorialen Variable

farbe <- c("rot","rot","blau","gruen","rot","blau")

tab <- table(farbe)

barplot(tab,

        main="Farben-Balkendiagramm",

        col=c("red","blue","green"))

• table(farbe) counts how often red, blue, and green occur.

• barplot() visualizes the results.

Scatter plot

For two numerical variables x and y:

x <- c(1,2,3,4,5)

y <- c(2,3,7,8,11)

plot(x, y, 

     main="Streudiagramm X vs Y", 

     xlab="X-Achse", 

     ylab="Y-Achse", 

     pch=19, 

     col="darkgreen")

• pch=19: filled points
• col=”darkgreen”: color

Plot customizations

Base R plotting has a whole range of parameters for changing the appearance:

• pch: Point type (19 = filled circle, 1 = open circle, etc.)
• xlim, ylim: Ranges of the x- and y-axes (e.g., xlim=c(0,10))
• axes=FALSE: Hide the axes (you may then need to draw them manually)
• par(mfrow=c(r,c)): Multiple plots on one page

Example: Multiple plots side by side

par(mfrow=c(1,2))  # 1 Zeile, 2 Spalten

hist(x, main="Hist X")

boxplot(x, main="Boxplot X")

Note: par(mfrow=…) remains in effect until you restart R or reset it with par(mfrow=c(1,1)).

Exporting graphics

With Base R, you can save your graphics in formats such as PNG, JPEG, PDF, and more.

Example:

png("mein_plot.png", width=600, height=400)

hist(x, main="Histogramm von x")

dev.off()

• png(“filename.png”, …): Opens a PNG “drawing canvas”.
• All plot commands in between are drawn to this file.
• dev.off() closes the file.

Alternatively:

pdf("mein_plot.pdf")

boxplot(x)

dev.off()

Conclusion

You now know the basic ideas and most important commands for Base R Graphics:

• hist(), boxplot(), plot(), barplot()
• Customization options via parameters
• Export to various formats