Format Axis Tick Labels to Percentage in Plotly in R

When working with data visualization, presenting values in an easily understandable way is crucial. One common task is to format axis tick labels as percentages, especially when dealing with proportions or rates. This article will guide you on how to achieve this using the plotly package in R.

Introduction to Plotly in R

Plotly is an interactive graphing library that allows users to create stunning and dynamic plots easily. It's widely used for its flexibility and integration with R Programming Language making it a powerful tool for data visualization.

Why Format Tick Labels to Percentage?

Presenting data in percentages makes it easier to understand proportions, comparisons, and distributions. Instead of showing raw numbers or fractions, converting them into percentages offers better clarity, especially in business reports, financial analysis, and academic research.

Getting Started with Plotly in R

Before we begin, you need to ensure that the plotly package is installed and loaded into your R environment. If you haven't installed it yet, you can do so by running:

install.packages("plotly")
library(plotly)

Basic Plot with Plotly in R

Let’s create a simple scatter plot as our base example before formatting the axis tick labels.

# Load the plotly library
library(plotly)

# Sample data
x_values <- c(0.1, 0.25, 0.5, 0.75, 1.0)
y_values <- c(0.2, 0.4, 0.6, 0.8, 1.0)

# Create a basic scatter plot
fig <- plot_ly(x = x_values, y = y_values, type = 'scatter', mode = 'markers')

# Display the plot
fig

Output:

By default, the values on both the x and y axes are displayed as decimals. We want to convert these into percentage formats.

How to Format Axis Tick Labels to Percentage in Plotly

The key to formatting tick labels as percentages is to use Plotly's tickformat attribute. This attribute allows you to specify how tick labels should be displayed. The tickformat parameter uses d3-format syntax to control how the numbers are displayed. To convert numbers into percentages, we will use the .0% format.

Step 1: Formatting the Y-Axis Tick Labels to Percentage

First we will Formatting the Y-Axis Tick Labels to Percentage.

# Formatting the y-axis tick labels as percentages
fig <- fig %>% layout(
  yaxis = list(
    tickformat = ".0%"  # Display as a percentage with no decimal places
  )
)

# Display the updated plot
fig

Output:

Step 2: Formatting Both X and Y-Axis Tick Labels to Percentage

You might want to format both axes to display percentages:

# Formatting both x and y-axis tick labels as percentages
fig <- fig %>% layout(
  xaxis = list(
    tickformat = ".0%"  # Display as a percentage with no decimal places
  ),
  yaxis = list(
    tickformat = ".0%"  # Display as a percentage with no decimal places
  )
)

# Display the updated plot
fig

Output:

Now both the x and y axes display values as percentages, making your plot much more intuitive. You might want to customize how many decimal places to display in your percentage labels. Here are a few variations:

• .0%: No decimal places (e.g., 50%)
• .1%: One decimal place (e.g., 50.0%)
• .2%: Two decimal places (e.g., 50.00%)

Customizing Other Aspects of the Plot

You can further customize the plot to make it more informative and visually appealing. For instance:

• Adding Titles: Use the title parameter within layout() to add titles to the plot and axes.
• Changing Colors: You can customize the color of the data points or bars using the marker attribute.
• Legend Positioning: Adjust the legend position using the legend attribute within layout().

Conclusion

Formatting axis tick labels to percentages in Plotly with R is a straightforward task that significantly enhances the readability and interpretation of your plots. By utilizing the tickformat attribute, you can quickly convert raw numerical values into percentages, making your visualizations more intuitive and aligned with the data's context.