Create a function that insert a line break between every letter of a character variable in R

What I want: to create a function to insert a line break between every letter of a character variable in R.

What I tried: but it didn't work

wrap_letters <- function(x){     z <- substring(x, 1, 1) # Take the first letter of x and save it in z    for(i in 2:stri_length(x)) { #from the second to the length of x    w  <- substring(x, i, 1)  #take the respective letter and save it to w    z <- paste0(z,"\n",  w) #paste z, "\n", w    }   z #return z  }    

Reproducible example with data (using ToothGrowth that comes within R):

df <- ToothGrowth %>%     mutate(dose = factor(dose),            supp = case_when(               supp=="OJ" ~ "orange juice",                T ~ "ascorbic acid"),            supp_label = wrap_letters(supp))  

Aplication: to vertically write labels in a facet_grid plot: I want to rotate letters to normal position (i.e. horizontal), but to place letters below each other, so they don't take too much width:

bp <- ggplot(df, aes(x=dose, y=len, group=dose)) +      geom_boxplot(aes(fill=dose)) +     theme(        strip.text.y = element_text(angle = 0)     ) +     facet_grid(supp_label ~ dose)  bp  

Desired result:

df <- ToothGrowth %>%     mutate(dose = factor(dose),            supp_label = case_when(               supp=="OJ" ~ "o\nr\na\nn\ng\ne\n \nj\nu\ni\nc\ne",                T ~ "a\ns\nc\no\nr\nb\ni\nc\n \na\nc\ni\nd"))    bp <- ggplot(df, aes(x=dose, y=len, group=dose)) +      geom_boxplot(aes(fill=dose)) +     theme(        strip.text.y = element_text(angle = 0)     ) +     facet_grid(supp_label ~ dose)  bp    

Note: This is a small reproducible example, I have more categories in my dataframe and I want to make everything reproducible, that is why I need a function.

https://stackoverflow.com/questions/67428819/create-a-function-that-insert-a-line-break-between-every-letter-of-a-character-v May 07, 2021 at 11:58AM