Understanding the R Plotting System and Adding a Check Mark Symbol to the Main Text

R is a popular programming language for statistical computing and graphics. The R plotting system allows users to create high-quality plots with ease. However, there are nuances to understanding how to manipulate the plot’s appearance and content. In this article, we will delve into the world of R plots and explore ways to add a check mark symbol next to the main text.

Introduction to R Plots

An R plot is created using the plot() function, which takes several arguments, including the main text (or title) that appears at the top of the plot. The main argument allows users to specify a string or expression that will be displayed as the title of the plot.

Understanding the Role of paste(), bquote(), and expression() in R

When working with strings and expressions in R, it is essential to understand how paste(), bquote(), and expression() functions work. These functions are used to concatenate strings or evaluate expressions.

paste() Function

The paste() function concatenates one or more strings together. However, when using paste() with the main argument in a plot, it converts the expression into a literal string, preventing evaluation of any embedded expressions.

# Using paste() to create a title
plot(1:10, main = paste("bbb", bquote(symbol(("\326")))), col.main = 2)

In this example, paste() is used to concatenate the strings “bbb” and symbol(("\326")). However, because paste() converts the expression into a literal string, it prevents evaluation of the symbol.

bquote() Function

The bquote() function allows users to embed expressions within quotes. It provides a way to evaluate embedded expressions without converting them into literal strings.

# Using bquote() to create a title
plot(1:10, main = bquote("bbb"~symbol(("\326"))), col.main = 2)

In this example, bquote() is used to embed the expression "bbb"~symbol(("\326")). The tilde (~) connector adds a space between the strings, allowing for proper spacing in the title.

expression() Function

The expression() function also allows users to create expressions that can be evaluated. It provides more flexibility than paste() or bquote(), especially when working with complex expressions.

# Using expression() to create a title
plot(1:10, main = expression(paste("bbb ", symbol(("\326")))), col.main = 2)

In this example, expression() is used to create an expression that includes the concatenated string “bbb” and symbol(("\326")). The space between the strings is achieved using a regular expression.

Using Connecors (~) in Titles

When using the bquote() function or expression(), users can utilize connectors (e.g., ~) to add spaces between embedded expressions. This ensures proper spacing and formatting for titles.

# Using connectors (~) in a title
plot(1:10, main = bquote("bbb"~symbol(("\326"))), col.main = 2)

In this example, the connector (~) adds a space between “bbb” and symbol(("\326")), resulting in proper spacing in the title.

Creating Titles with Multiple Lines

Users can create titles that span multiple lines by using newline characters. The newline character is represented as \n or "\n".

# Creating a multi-line title
plot(1:10, main = expression(paste("Line 1", "\n", "Line 2")), col.main = 2)

In this example, the expression uses paste() to concatenate two strings separated by a newline character (\n). The resulting title has two lines.

Creating Titles with Formula Expressions

Users can create titles that incorporate formula expressions. To do so, use the bquote() or expression() functions with formula expressions.

# Using bquote() with a formula expression
plot(1:10, main = bquote("Line 2 * 3 + Line 1"), col.main = 2)

In this example, the formula expression "Line 2 * 3 + Line 1" is embedded within the bquote() function. The resulting title includes an arithmetic expression.

Using bquote() and expression() with Multiple Arguments

Both bquote() and expression() allow users to pass multiple arguments to create complex titles.

# Using bquote() with multiple arguments
plot(1:10, main = bquote("bbb"~symbol(("\326"))~"abc"), col.main = 2)

In this example, the bquote() function embeds multiple expressions within quotes. The resulting title includes three parts.

Creating Titles in Other Packages

While we have focused on R plots created using plot(), some packages use different syntax for titles or require explicit formatting. For example:

• ggplot2: In ggplot2, titles are specified using the title argument within the ggsave() function.

Using ggplot2

library(ggplot2) ggplot(mtcars, aes(x = wt, y = mpg)) + geom_point() + labs(title = “Title with ggplot2”, subtitle = “Subtitle”)

*   **Shiny**: In Shiny apps, titles are specified using the `title` argument within the `ui()` function.
    ```r
# Using Shiny
library(shiny)
library(ggplot2)

ui <- fluidPage(
  title = expression(paste("Title", "\n", "Subtitle"))
)

• knitr: In knitr, titles are specified using the title argument within the knit() function.

Using knitr

library(knitr)

knit(title = “Title with knitr”)

Last modified on 2025-01-14