在ggplot2中粘贴标签的函数

Question

In the following plot, I want to rename x-axis by paste0 function.

daata <- data.frame(
  q = paste0("q",1:20),
  value = runif(n = 20, 2, 10))

ggplot2::ggplot(data = daata, aes(x = q, y = value)) +
  geom_col()

so I used the following code:

q = paste0("q",1:20)
labels <- paste0("'", q,"'" , " = ", 1:20) %>% noquote()
# Or
labels <- noquote(paste0("'", q,"'" , " = ", 1:20))

ggplot2::ggplot(data = daata, aes(x = q, y = value)) +
  geom_col() + 
  scale_x_discrete(labels = labels)

But it did not work. Why? (main question)

I want to search for solutions that make labels = c("'q1' = 1", ...) works.

Beside paste function I know two alternatives.

Using list:

 labels = sapply(1:20, list) names(labels) <- daata$q ggplot2::ggplot(data = daata, aes(x = q, y = value)) + geom_col() + scale_x_discrete(labels = labels) 

Using function:

 ggplot2::ggplot(data = daata, aes(x = q, y = value)) + geom_col() + scale_x_discrete(labels = function(i){gsub("q", "", i)}) 

I am eager to know other solutions too.

Answer 1

How about something like this? Extract the question number in the data = step, and use that for the axis:

daata <- data.frame(
  q = paste0("q",1:20),
  value = 1:20)

ggplot2::ggplot(data = daata %>% mutate(order = str_remove(q, "q") %>% as.numeric),
                aes(x = order,  y = value)) +
  geom_col() +
  scale_x_continuous(breaks = 1:20, minor_breaks = NULL)

Edit: here's an alternative that extracts the numeric part of the label. As you'll note, this preserves the alphabetical ordering created by mapping x to q .

ggplot2::ggplot(data = daata, aes(x = q, y = value)) +
  geom_col() + 
  scale_x_discrete(labels = function(x) parse_number(x))

Answer 2

why not giving a named vector?

labels <- parse_number(as.character(daata$q))
names(labels) <- as.character(daata$q)

p1 <- ggplot2::ggplot(data = daata, aes(x = q, y = value)) +
  geom_col() 

p2 <- p1  + scale_x_discrete(labels = labels)
cowplot::plot_grid(p1, p2, nrow = 1)