Understanding Bar Plots and Centering X-Axis Ticks
Introduction to Bar Plots and Line Plots
In data visualization, bar plots and line plots are two common types of graphs used to display data. A bar plot consists of rectangular bars that represent categorical data, while a line plot displays the trend or pattern of continuous data over time. In this article, we will focus on creating a bar plot with line plots and explore how to center the x-axis ticks.
The Problem with Centering X-Axis Ticks
When combining bar plots and line plots, it can be challenging to center the x-axis ticks. The problem arises because both types of graphs use different scaling parameters for their x-axis. The x-axis in a bar plot represents the categories, while the x-axis in a line plot represents the time or value.
Creating Bar Plots with Line Plots
To create a bar plot combined with a line plot, we need to understand how to position both types of graphs on the same axis. We will use R as our programming language for this example.
Importing Required Libraries and Data
We start by importing the required libraries: ggplot2 for creating bar plots, base graphics for creating line plots, and random for generating random data.
# Load necessary libraries
library(ggplot2)
library(basegraphics)
# Generate random data
con <- seq(as.Date("2014-01-01"), as.Date("2014-12-31"), "month")
barData <- as.data.frame(con, stringsAsFactors = FALSE)
y <- runif(12, 0, 100)
lineData <- data.frame(x = con, y = y)
Creating Bar Plots with Line Plots
We create the bar plot using ggplot2 and position it on the same axis as the line plot.
# Create bar plot
barplot(barData, col = "green", xlab = "", ylab = "", ylim = c(0, max(con) * 1.1), axes = FALSE)
# Create line plot
par(new = TRUE)
plot(x = con, type = "b", col = "blue", axes = FALSE, xlab = "", ylab = "", ylim = c(0, max(y) * 1.1))
# Add red lines to line plot
lines(x = con, y = lineData$y, type = "b", col = "red")
Centering X-Axis Ticks
To center the x-axis ticks, we need to adjust the limits of both plots.
# Set x-axis limits for bar plot
xlim <- c(0, length(con)*1.25)
# Create line plot with centered x-axis ticks
par(new = TRUE)
plot(x = con, type = "b", col = "blue", axes = FALSE, xlab = "", ylab = "", ylim = c(0, max(y) * 1.1), xlim = xlim)
Alternative Approach Using axis Function
We can also center the x-axis ticks by adjusting the limits using the axis function.
# Create line plot with centered x-axis ticks
par(new = TRUE)
plot(x = con, type = "b", col = "blue", axes = FALSE, xlab = "", ylab = "", ylim = c(0, max(y) * 1.1))
# Center x-axis ticks
axis(1, at = xlim, labels = timeline)
# Add red lines to line plot
lines(x = con, y = lineData$y, type = "b", col = "red")
Conclusion
In conclusion, creating a bar plot combined with a line plot requires adjusting the limits of both plots. By using the axis function or adjusting the limits directly, we can center the x-axis ticks and create visually appealing graphs.
Further Reading
Last modified on 2024-02-15