Understanding R Markdown and LaTeX Output
===============
As a technical blogger, I’ve encountered various issues with R Markdown and LaTeX output. In this article, we’ll explore one such issue involving sapply and its impact on LaTeX output.
Introduction to R Markdown and LaTeX
R Markdown is a format for authoring documents that combines the power of Markdown formatting with the functionality of R programming language. It allows users to create reports, articles, and other types of documents using R code.
Latex is a typesetting system used for producing high-quality printed and digital documents. In R Markdown, we can use LaTeX to generate tables, figures, and other graphical elements.
The Problem: sapply and LaTeX Output
The problem arises when we try to use sapply with LaTeX output in R Markdown. As shown in the example code below, lapply runs without any issues, but sapply introduces an unwanted character at the beginning of line 87 in the LaTeX file.
---
title: "reprex"
output:
pdf_document:
latex_engine: xelatex
editor_options:
chunk_output_type: console
---
library(tidyverse)
library(kableExtra)
species = c("Human", "Droid")
lapply(species, function(x){
starwars %>%
select(name, birth_year) %>%
kable() %>%
kable_styling(fixed_thead = TRUE, latex_options = c("striped", "scale_down"))%>%
row_spec(0, bold = TRUE)
})
library(tidyverse)
library(kableExtra)
species = c("Human", "Droid")
sapply(species, function(x){
starwars %>%
select(name, birth_year) %>%
kable() %>%
kable_styling(fixed_thead = TRUE, latex_options = c("striped", "scale_down"))%>%
row_spec(0, bold = TRUE)
})
Understanding the Issue
The issue arises because sapply returns a vector of characters instead of a list like lapply. This is due to the fact that sapply uses rbind() internally, which creates a vector of characters.
str(sapply(species, function(x){
starwars %>%
dplyr::filter(species == x) %>%
select(name, birth_year) %>%
kable() %>%
kable_styling(fixed_thead = TRUE, latex_options = c("striped", "scale_down")) %>%
row_spec(0, bold = TRUE)
}, simplify = FALSE)[[1]])
#> 'kableExtra' chr "<table class=\"table\" style=\"margin-left: auto; margin-right: auto;\">\n <thead>\n <tr>\n <th style=\"text"| __truncated__
A Possible Solution
One possible solution to this issue is to add a line in the function that actually does something with the variable x. For example, we could filter the data using dplyr.
library(tidyverse)
library(kableExtra)
species = c("Human", "Droid")
str(sapply(species, function(x){
starwars %>%
dplyr::filter(species == x) %>%
select(name, birth_year) %>%
kable() %>%
kable_styling(fixed_thead = TRUE, latex_options = c("striped", "scale_down")) %>%
row_spec(0, bold = TRUE)
}, simplify = FALSE)[[1]])
#> 'kableExtra' chr "<table class=\"table\" style=\"margin-left: auto; margin-right: auto;\">\n <thead>\n <tr>\n <th style=\"text"| __truncated__
By doing so, we can compare the output of sapply with and without filtering.
library(tidyverse)
library(kableExtra)
species = c("Human", "Droid")
str(sapply(species, function(x){
starwars %>%
dplyr::filter(species == x) %>%
select(name, birth_year) %>%
kable() %>%
kable_styling(fixed_thead = TRUE, latex_options = c("striped", "scale_down")) %>%
row_spec(0, bold = TRUE)
}, simplify = FALSE)[[1]])
#> 'kableExtra' chr "<table class=\"table\" style=\"margin-left: auto; margin-right: auto;\">\n <thead>\n <tr>\n <th style=\"text"| __truncated__
str(sapply(species, function(x){
starwars %>%
dplyr::filter(species == x) %>%
select(name, birth_year) %>%
kable() %>%
kable_styling(fixed_thead = TRUE, latex_options = c("striped", "scale_down")) %>%
row_spec(0, bold = TRUE)
}, simplify = TRUE)[[1]])
#> chr "<table class=\"table\" style=\"margin-left: auto; margin-right: auto;\">\n <thead>\n <tr>\n <th style=\"text"| __truncated__
Conclusion
In conclusion, the issue with sapply and LaTeX output in R Markdown arises because sapply returns a vector of characters instead of a list like lapply. To fix this issue, we can add a line in the function that actually does something with the variable x, such as filtering the data.
By doing so, we can compare the output of sapply with and without filtering. This will help us understand why sapply is returning a vector of characters instead of a list like lapply.
References
reprex: A package for creating reproducible examples in R.kableExtra: An extension to thekable()function in R, providing more formatting options.
Additional Resources
R Markdown Documentation: The official documentation for R Markdown.Knitr Documentation: The official documentation for Knitr.
Last modified on 2023-06-11