Dual Y Axis Chart

The dual Y-axis graph can put two groups of data with larger orders of magnitude in the same graph for display.

Setup

• System Requirements: Cross-platform (Linux/MacOS/Windows)

• Programming language: R

• Dependent packages: data.table; jsonlite; ggplot2

# Install packages
if (!requireNamespace("data.table", quietly = TRUE)) {
  install.packages("data.table")
}
if (!requireNamespace("jsonlite", quietly = TRUE)) {
  install.packages("jsonlite")
}
if (!requireNamespace("ggplot2", quietly = TRUE)) {
  install.packages("ggplot2")
}

# Load packages
library(data.table)
library(jsonlite)
library(ggplot2)

Data Preparation

The loaded data is divided into three columns, the first column is the value of the x-axis, the second column is the value of the left Y-axis, and the third column is the value of the right Y-axis.

# Load data
data <- data.table::fread(jsonlite::read_json("https://hiplot.cn/ui/basic/dual-y-axis/data.json")$exampleData$textarea[[1]])
data <- as.data.frame(data)

# View data
head(data)

  x     data1     data2
1 1 0.6105444 1000.5383
2 2 0.9961953  981.0398
3 3 0.6314076  961.0601
4 4 0.8651855  941.2540
5 5 0.8169382  922.3971
6 6 0.1877025  903.3067

Visualization

# Dual Y Axis Chart
p <- ggplot(data, aes(x = x)) +
  geom_line(aes(y = data[, 2]), size = 1, color = "#D72C15") +
  geom_line(aes(y = data[, 3] / as.numeric(10)), size = 1, color = "#02657B") +
  scale_y_continuous(
    name = colnames(data)[2],
    sec.axis = sec_axis(~ . * as.numeric(10), name = colnames(data)[3])) +
  ggtitle("Dual Y Axis Chart") + xlab("x") +
  theme_bw() +
  theme(text = element_text(family = "Arial"),
        plot.title = element_text(size = 12,hjust = 0.5),
        axis.title = element_text(size = 12),
        axis.text = element_text(size = 10),
        axis.text.x = element_text(angle = 0, hjust = 0.5,vjust = 1),
        legend.position = "right",
        legend.direction = "vertical",
        legend.title = element_text(size = 10),
        legend.text = element_text(size = 10))

p

Figure 1: Dual Y Axis Chart

Interpretation of case statistics graphics In the case data, the Y-axis scale on the left is in the range of 0-100, while the Y-axis scale on the right is 0-1000.