Add legends without border and with white background in R

A legend is defined as an area of the graph plot describing each of the parts of the plot. The legend plot is used to show statistical data in graphical form. We can add a legend to a graph using the legend() function. In this article, we will see how to add plot legends without border and with white background in R Programming Language. 

By Default legend() function generate legend with the border as we will see further. Firstly, let’s just create a normal bar graph without any legend. 

Syntax: barplot(H, xlab, ylab, main, names.arg, col)

Parameters:

• H: This parameter is a vector or matrix containing numeric values which are used in bar chart.
• xlab: This parameter is the label for x axis in bar chart.
• ylab: This parameter is the label for y axis in bar chart.
• main: This parameter is the title of the bar chart.
• names.arg: This parameter is a vector of names appearing under each bar in bar chart.
• col: This parameter is used to give colors to the bars in the graph.

Example:

R

colors = c("green", "orange", "brown")
months <- c("Mar", "Apr", "May", "Jun", "Jul")

# Create the matrix of the values.
Values <- matrix(c(2, 9, 3, 11, 9, 4, 8, 7, 3, 12,
                   5, 2, 8, 10, 11),

                 nrow = 3, ncol = 5, byrow = TRUE)

# Create the bar chart
barplot(Values, main = "Total Revenue", names.arg = months,
        xlab = "Month", ylab = "Revenue",
        col = colors, beside = TRUE)

Output:

Simple BarChart

Now we add legends to the above graph using legend() function.

Syntax : legend(x, y, legend, fill, col, bg, lty, cex, title, text.font, bg)

Parameters :

• x and y : co-ordinates to be used to position the legend
• legend : Text of the legend
• fill : Colors to be used to fill the boxes of legend
• col : Colors of lines
• bg : It defines background color for the legend box. (optional)
• title : Legend title        (optional)
• text.font : An integer specifying the font style of the legend (optional)

Return : Legend of Plot

Example:

R

colors = c("green", "orange", "brown")
months <- c("Mar", "Apr", "May", "Jun", "Jul")
regions <- c("East", "West", "North")

# Create the matrix of the values.
Values <- matrix(c(2, 9, 3, 11, 9, 4, 8, 7, 3, 12,
                   5, 2, 8, 10, 11),

                 nrow = 3, ncol = 5, byrow = TRUE)

# Create the bar chart
barplot(Values, main = "Total Revenue", names.arg = months,
        xlab = "Month", ylab = "Revenue",
        col = colors, beside = TRUE)

# Add the legend to the chart
legend(1,12, regions, cex = 1.0, fill = colors)

Output:

BarChart with legend

You can see in the above output graph, the legend was in black border. Now we will remove the border and add white background to the plot using box.col parameter inside legend() function and set its value to white for white background.

Example:

R

colors = c("green", "orange", "brown")
months <- c("Mar", "Apr", "May", "Jun", "Jul")
regions <- c("East", "West", "North")

# Create the matrix of the values.
Values <- matrix(c(2, 9, 3, 11, 9, 4, 8, 7, 3, 12,
                   5, 2, 8, 10, 11),

                 nrow = 3, ncol = 5, byrow = TRUE)

# Create the bar chart
barplot(Values, main = "Total Revenue", names.arg = months,
        xlab = "Month", ylab = "Revenue",
        col = colors, beside = TRUE)

# Add the legend to the chart without border
# and with white background
legend(1,12, regions, cex = 1.0, fill = colors, box.col = "white")

Output:

Plot Legends without border and with white background