How to Create an Animated Line Graph using Plotly

An animated line graph is a visual representation of data that changes over time or over a categorical variable. It can be a powerful tool for visualizing trends and patterns in data and can help to communicate complex ideas in a clear and concise way. In this tutorial, we will learn how to create an animated line graph using the Plotly library in R Programming Language.

Before we dive into the steps for creating an animated line graph, it’s important to understand some of the key concepts and terminology related to this type of visualization.

• Frame: In an animated line graph, each frame represents a different point in time or a different category. When the frame changes, the data points on the graph are updated to reflect the new data.
• Animation Attributes: The animation attributes are the settings that control how the animation behaves. For example, you can specify the duration of each frame, the easing function used to transition between frames, and whether to start the animation from the current frame or from the beginning.

Now that we’ve covered the basic concepts, let’s take a look at the steps needed to create an animated line graph using Plotly in R. Load the required libraries: To use the Plotly library in R, you will need to install it first and then load it.

R

# Load the Plotly and data.table libraries
library(plotly)
library(data.table)

Before you can create an animated line graph, you will need to have some data to visualize. You can use your own data, or you can load one of the built-in datasets available in R.

R

# Load the mpg dataset
data(mpg)

Convert the data to a data table: Plotly works best with data stored in a data table format. To convert your data to a data table, you can use the as.data.table() function. For example dt <- as.data.table(mtcars).

R

# Convert the mpg data to a data table
dt <- as.data.table(mpg)

To create a Plotly line graph, you can use the plot_ly() function. You will need to specify the x and y variables, as well as the type and mode of the graph. 

R

# Create a Plotly line graph
p <- plot_ly(dt, x = ~displ,
             y = ~hwy,
             type = "scatter",
             mode = "lines",
             frame = ~class)

To make the line graph animated, you will need to add the animation_frame and animation_opts attributes to the graph. The animation_frame attribute specifies which column to use as the animation frame, and the animation_opts attribute contains a list of options that control the behaviour of the animation. 

R

# Add the animation attributes
p <- layout(p,
            animation_opts =
            list(frame = list(duration = 500,
                              redraw = TRUE)))

# Display the graph
p

Output:

Animated Line Graph using Plotly

• A graph or plot object is represented by the variable p. The layout(p,…) instruction in the code first applies a layout to the graph. The… stands for more inputs or choices that may be made for the layout function.
• An animation_opts argument, which is set to a list containing another list of options, is located inside the layout function. The choices listed are:
• Frame: It appears to be in charge of the animation frames.
• duration: A value of 500 milliseconds for each frame’s duration. This indicates that each frame of the animation will last 30 frames.
• Redraw: A boolean value indicating whether or not the graph needs to be redrawn for every animation frame. The graph will be redrawn for each frame if the value is set to TRUE.

Example 2:

R

# Load the Plotly and data.table libraries
library(plotly)
library(data.table)

# Load the mtcars dataset
data(mtcars)

# Convert the mtcars data to a data table
dt <- as.data.table(mtcars)

# Set custom colors for each frame
colors <- c("#FF0000", "#00FF00", "#0000FF")

# Create a Plotly line graph
p <- plot_ly(dt, x = ~wt, y = ~mpg,
             type = "scatter",
             mode = "lines",
             frame = ~cyl,
             color = ~cyl) %>%
  style(marker = list(color = ~cyl,
                      colors = colors))

# Add the animation attributes
p <- layout(p,
            animation_opts =
            list(frame = list(duration = 5000,
                              redraw = TRUE)))

# Display the graph
p

Output:

Animated Line Graph using Plotly with color changes

• mode = “lines” instructs the plot to display lines rather than specific markers.
• frame = cyl: This specifies that the animation frames should be based on the data’s cyl column, which implies that each different value of cyl will result in a single frame.
• The colour of the plot elements (lines or markers) is determined by the cyl column using the formula colour = cyl.
• Style: list (marker = colour = cyl, colours = colours).
• colour = cyl, colours = colours, marker = list Based on the cyl column, it determines the colour of the marks. A colour scheme should be present in the colours variable.
• layout(p, animation_opts = list) using the formula (frame = list(duration = 5000, redraw = TRUE)).
• layout: The plot’s layout can be changed using this function.
• animation_opts: Options for animation can be set up.

frame = list(redraw = TRUE, time = 5000): It outlines the options for the animation frames. Each frame’s duration is set to 5000 milliseconds (5 seconds) using the duration option.