# Dot Charts - R Base Graphs

Previously, we described the essentials of R programming and provided quick start guides for importing data into R.

Here, we’ll describe how to draw a Cleveland dot plot in R.

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 as described here: Fast reading of data from txt|csv files into R: readr package.

Here, we’ll use the R built-in mtcars data set.

# Data

We’ll use mtcars data sets. We start by ordering the data set according to mpg variable.

``mtcars <- mtcars[order(mtcars\$mpg), ]``

# R base function: dotchart()

The function dotchart() is used to draw a cleveland dot plot.

``````dotchart(x, labels = NULL, groups = NULL,
gcolor = par("fg"), color = par("fg"))``````

• x: numeric vector or matrix
• labels: a vector of labels for each point.
• groups: a grouping variable indicating how the elements of x are grouped.
• gcolor: color to be used for group labels and values.
• color: the color(s) to be used for points and labels.

# Dot chart of one numeric vector

``````# Dot chart of a single numeric vector
dotchart(mtcars\$mpg, labels = row.names(mtcars),
cex = 0.6, xlab = "mpg")``````

``````# Plot and color by groups cyl
grps <- as.factor(mtcars\$cyl)
my_cols <- c("#999999", "#E69F00", "#56B4E9")
dotchart(mtcars\$mpg, labels = row.names(mtcars),
groups = grps, gcolor = my_cols,
color = my_cols[grps],
cex = 0.6,  pch = 19, xlab = "mpg")``````

# Dot chart of a matrix

``````dotchart(VADeaths, cex = 0.6,
main = "Death Rates in Virginia - 1940")``````

# Infos

This analysis has been performed using R statistical software (ver. 3.2.4).

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