How to loop through third variable? - r

Question

I have adapted the codes below which I referred from https://statsandr.com/blog/how-to-do-a-t-test-or-anova-for-many-variables-at-once-in-r-and-communicate-the-results-in-a-better-way/#to-go-even-further into my dataset:
Day<-c(1,1,1,1,1,1,1,1,1,2,2,2,2,2,2,2,2,2,2)
Group<-c("A","A","A","B","B","B","C","C","C","A","A","A","A","B","B","B","C","C","C")
Rain<-c(4,4,6,5,3,4,5,5,3,6,6,6,5,3,3,3,2,5,2)
UV<-c(6,6,7,8,5,6,5,6,6,6,7,7,8,8,5,6,8,5,7)
dat<-data.frame(Day,Group,Rain,UV)
x <- which(names(dat) == "Group")
y <- which(names(dat) == "Rain"
| names(dat) == "UV")
method1 <- "kruskal.test"
method2 <- "wilcox.test"
my_comparisons <- list(c("A", "B"), c("A", "C"), c("B", "C")) # comparisons for post-hoc test
library(ggpubr)
for (i in y) {
for (j in x) {
p <- ggboxplot(dat,
x = colnames(dat[j]), y = colnames(dat[i]),
color = colnames(dat[j]),
legend = "none",
palette = "npg",
add = "jitter"
)
print(
p + stat_compare_means(aes(label = paste0(..method.., ", p-value = ", ..p.format..)),
method = method1, label.y = max(dat[, i], na.rm = TRUE)
)
+ stat_compare_means(comparisons = my_comparisons, method = method2, label = "p.format")
)
}
}
How do I further repeat this function through different "Day"? Thanks.

Answer 1

I think you want to see the results for each day, right? You can add a third loop like this:
for (h in unique(dat$Day)) {
for (i in y) {
for (j in x) {
dat_tmp <- dat[dat$Day == h,] # create a subset of the data for each day
p <- ggboxplot(dat_tmp,
x = colnames(dat_tmp[j]), y = colnames(dat_tmp[i]),
color = colnames(dat_tmp[j]),
legend = "none",
palette = "npg",
add = "jitter"
)
print(
p + stat_compare_means(aes(label = paste0(..method.., ", p-value = ", ..p.format..)),
method = method1, label.y = max(dat_tmp[, i], na.rm = TRUE)
)
+ stat_compare_means(comparisons = my_comparisons, method = method2, label = "p.format")
)
}
}
}
I added a third loop to your code and created dat_tmp inside the loop, which becomes the dataset that you use for the analyses of each day.