using plotmath in ggrepel labels - r

Question

I am trying to create a plot where I want to show all coefficients from my linear model and their respective statistical details attached at each point using ggrepel package. I have managed to create the basic plot, but what I haven't been able to figure out is how to use plotmath while creating labels. So, for example, in the plot produced below, I would like to use italics for the t-value (t) and p-value (p). Additionally, if I were to include estimates, I might also want to include the greek letter beta (β) in the label.
# loading needed libraries
library(ggrepel)
#> Loading required package: ggplot2
library(ggplot2)
library(GGally)
library(tidyverse)
# creating a dataframe containing results
(label_df <- broom::tidy(x = stats::lm(data = mtcars, wt ~ am*cyl), conf.int = TRUE) %>%
dplyr::filter(.data = ., term != "(Intercept)") %>%
dplyr::select(.data = ., term, estimate, conf.low, conf.high, statistic, p.value) %>%
purrrlyr::by_row(
.d = .,
..f = ~ paste(
"t = ",
round(.$statistic, digits = 3),
", p = ",
round(.$p.value, digits = 3),
sep = ""
),
.collate = "rows",
.to = "label",
.labels = TRUE
)
)
#> # tibble [3 x 7]
#> term estimate conf.low conf.high statistic p.value label
#> <chr> <dbl> <dbl> <dbl> <dbl> <dbl> <chr>
#> 1 am -0.956 -2.58 0.668 -1.21 0.238 t = -1.206, p = 0~
#> 2 cyl 0.304 0.135 0.473 3.68 0.000989 t = 3.678, p = 0.~
#> 3 am:cyl 0.0328 -0.234 0.300 0.252 0.803 t = 0.252, p = 0.~
# creating the model coefficient plot using ggcoef
plot <- GGally::ggcoef(x = stats::lm(data = mtcars, wt ~ am*cyl), exclude_intercept = TRUE)
# adding labels using ggrepel
plot +
ggrepel::geom_label_repel(
data = label_df,
mapping = ggplot2::aes(x = estimate, y = term, label = label),
size = 3,
box.padding = grid::unit(x = 0.75, units = "lines"),
fontface = "bold",
direction = "y",
color = "black",
label.size = 0.25,
segment.color = "black",
segment.size = 0.5,
segment.alpha = NULL,
min.segment.length = 0.5,
max.iter = 2000,
point.padding = 0.5,
force = 2,
na.rm = TRUE
)
If I use something like base::substitute or base::bquote to create the label inside purrrlyr, I get the following error:
.f must return either data frames or vectors for non-list collation
I can get rid of this error by converting it to character type but then the labels get all messed-up.
# creating a dataframe containing results
(label_df <- broom::tidy(x = stats::lm(data = mtcars, wt ~ am*cyl), conf.int = TRUE) %>%
dplyr::filter(.data = ., term != "(Intercept)") %>%
dplyr::select(.data = ., term, estimate, conf.low, conf.high, statistic, p.value) %>%
purrrlyr::by_row(
.d = .,
..f = ~ as.character(bquote(
"t = "~.(round(.$statistic, digits = 3))~
", p = "~
.(round(.$p.value, digits = 3))
)),
.collate = "rows",
.to = "label",
.labels = TRUE
)
)
#> # tibble [9 x 8]
#> term estimate conf.low conf.high statistic p.value .row label
#> <chr> <dbl> <dbl> <dbl> <dbl> <dbl> <int> <chr>
#> 1 am -0.956 -2.58 0.668 -1.21 0.238 1 ~
#> 2 am -0.956 -2.58 0.668 -1.21 0.238 1 "\"t = \" ~~
#> 3 am -0.956 -2.58 0.668 -1.21 0.238 1 0.238
#> 4 cyl 0.304 0.135 0.473 3.68 0.000989 2 ~
#> 5 cyl 0.304 0.135 0.473 3.68 0.000989 2 "\"t = \" ~~
#> 6 cyl 0.304 0.135 0.473 3.68 0.000989 2 0.001
#> 7 am:cyl 0.0328 -0.234 0.300 0.252 0.803 3 ~
#> 8 am:cyl 0.0328 -0.234 0.300 0.252 0.803 3 "\"t = \" ~~
#> 9 am:cyl 0.0328 -0.234 0.300 0.252 0.803 3 0.803
Created on 2018-06-13 by the reprex package (v0.2.0).

Answer 1

Based on discussion in the comments, you need to use mathematical annotations correctly to avoid errors, see link.
The below label format works for me, and includes beta-estimates with the Greek symbol. list is needed to obtain commas in plotmath.
(label_df <- broom::tidy(x = stats::lm(data = mtcars, wt ~ am*cyl), conf.int = TRUE) %>%
dplyr::filter(.data = ., term != "(Intercept)") %>%
dplyr::select(.data = ., term, estimate, conf.low, conf.high, statistic, p.value) %>%
purrrlyr::by_row(
.d = .,
..f = ~ paste(
"list(italic(t)==",
round(.$statistic, digits = 3),
", ~italic(p)==",
round(.$p.value, digits = 3),
", ~beta==",
round(.$estimate, digits = 3),
")",
sep = ""
),
.collate = "rows",
.to = "label",
.labels = TRUE
)
)