How to plot two `ggscatter` correlation plots with confidence intervals on the same graph in R?-CodePudding

I am trying to get a spearman correlation for two scatter plots with confidence intervals on the same graph but it is proving difficult to do.

Given the following data:

spentWithTool <- sample(1:7, 20, replace = TRUE)
understoodWithTool <- sample(1:5, 20, replace = TRUE)
spentWithoutTool <- sample(1:4, 10, replace = TRUE)
understoodWithoutTool <- sample(1:5, 10, replace = TRUE)

This is the best workaround I came up with but it is not what I want - I want the withTool and the withoutTool plots to be on the same graph and NOT side by side.

plot_with <- ggscatter(data = data.frame(spentWithTool, understoodWithTool),
                     x = 'spentWithTool',
                     y = 'understoodWithTool',
                     color = 'darkred',
                     cor.method = "spearman",
                     cor.coef = TRUE,
                     conf.int = TRUE,
                     add = "reg.line",
                     add.params = list(color = 'red'),
                    )
plot_without <- ggscatter(data = data.frame(spentWithoutTool, understoodWithoutTool),
                      x = 'spentWithoutTool',
                      y = 'understoodWithoutTool',
                      color = 'darkblue',
                      cor.method = "spearman",
                      cor.coef = TRUE,
                      conf.int = TRUE,
                      add = "reg.line",
                      add.params = list(color = 'blue')
ggarrange(plotlist = list(plot_with, plot_without))

The above gives me:

Using ggpar(p = list(plot_with, plot_without)) just created two separate graphs so it was not helpful.

I am trying to get two lines (red and blue), where each line represents withTool and withoutTool respectively and the x and y axis represent timeSpent and understood respectively. Ideally, the confidence intervals, would be the same colour as what the line represents (red for withTool and blue for withoutTool).

Is there a way to get both correlation lines and points on the same graph?

Aside - Is there a way to use ggscatter without creating a data frame from vectors?

CodePudding user response：

After checking out the docs and trying several options using the color and ggp arguments of ggscatter IMHO the easiest and less time-consuming option to achieve your desired result would be to build your plot from scratch using ggplot2 with some support from ggpubr to add the regression equations and the theme:

set.seed(1)

spentWithTool <- sample(1:7, 20, replace = TRUE)
understoodWithTool <- sample(1:5, 20, replace = TRUE)
spentWithoutTool <- sample(1:4, 10, replace = TRUE)
understoodWithoutTool <- sample(1:5, 10, replace = TRUE)

library(ggplot2)
library(ggpubr)

df <- rbind.data.frame(
  data.frame(x = spentWithTool, y = understoodWithTool, id = "with"),
  data.frame(x = spentWithoutTool, y = understoodWithoutTool, id = "without")
  
)

ggplot(df, aes(x, y, color = id, fill = id))  
  geom_point()  
  geom_smooth(method = "lm")  
  stat_cor(method = "spearman")  
  scale_color_manual(values = c(with = "red", without = "blue"), aesthetics = c("color", "fill"))  
  theme_pubr()  
  labs(x = "timeSpent", y = "understood")
#> `geom_smooth()` using formula = 'y ~ x'