Creating Multiple Plots from a List of DataFrames in R

Introduction

In this article, we will explore how to create multiple plots from a list of dataframes in R. We will use the ggplot2 library for creating ggplots and the cowplot library for creating multi-panel plots.

Background

The ggplot2 library provides a powerful data visualization tool that allows us to create high-quality plots with ease. However, when working with large datasets or multiple panels, it can be challenging to manage the code. In this article, we will explore how to use R’s built-in functions and libraries to create multiple plots from a list of dataframes.

Creating Multiple Plots

The ggplot2 library provides several ways to create multiple plots. One common method is to use the par(mfrow) function in base R, which allows us to specify the number of rows and columns for our plot. However, this approach can be cumbersome when working with large datasets or multiple panels.

A better approach is to use the ggplot2 library’s built-in functions for creating multi-panel plots. One popular option is the plot_grid() function from the cowplot library. This function allows us to create a grid of plots from a list of ggplots.

Step 1: Load Required Libraries

To get started, we need to load the required libraries:

library(ggplot2)
library(cowplot)

Step 2: Create a List of Dataframes

Next, we need to create a list of dataframes. For this example, let’s assume that our data is stored in a list called Turbine. We can use the lapply() function to create a new list with 5 dataframes:

Turbine = lapply(1:5, data.frame(TS=1:10, Pv..turbine=runif(10)))

Step 3: Create ggplots from the Dataframes

Now that we have our list of dataframes, we can create ggplots from each dataframe using the ggplot() function:

myplots = lapply(Turbine, function(x) {
  ggplot(x, aes(x=TS, y=Pv..turbine)) +
    geom_point(size=1)
})

Step 4: Create a Multi-Panel Plot

Finally, we can use the plot_grid() function to create a multi-panel plot from our list of ggplots:

library(cowplot)

plot_grid(plotlist=myplots, ncol=5)

This code creates a grid of 5 panels, each containing one of our ggplots.

Example Use Case: Visualizing Wind Turbine Data

Let’s assume that we have a dataset of wind turbine data with 5 years of data. We can use the Turbine list to create a multi-panel plot that shows the PV output for each year:

Turbine = lapply(1:5, function(i) {
  data.frame(TS=1:10, Pv..turbine=runif(10))
})

myplots = lapply(Turbine, function(x) {
  ggplot(x, aes(x=TS, y=Pv..turbine)) +
    geom_point(size=1)
})

library(cowplot)

plot_grid(plotlist=myplots, ncol=5)

This code creates a multi-panel plot that shows the PV output for each year. The x-axis represents time (in hours), and the y-axis represents the PV output.

Conclusion

In this article, we explored how to create multiple plots from a list of dataframes in R using the ggplot2 library and the cowplot library. We covered the basics of creating multi-panel plots, including using the par(mfrow) function in base R versus the plot_grid() function in the cowplot library.

By following these steps and examples, you should be able to create high-quality multi-panel plots from your own dataset of dataframes. Remember to experiment with different plot types, colors, and sizes to find the best way to visualize your data.

Additional Resources

The ggplot2 manual: https://ggplot2.tidyverse.org/man/vggplot.html
The cowplot manual: https://cran.r-project.org/package=cowplot

Last modified on 2023-07-11