R: Conditional Formatting across excel files - r

Question

I am trying to highlight rows of an excel file based on a match from the columns in a separate excel file. Pretty much, I want to highlight a row in file1 if a cell in that row matches a cell in file2.
I saw the R package "conditionalFormatting" has some of this functionality, but I cannot figure out how to use it.
the pseudo-code i think would look something like this:
file1 <- read_excel("file1")
file2 <- read_excel("file2")
conditionalFormatting(file1, sheet = 1, cols = 1:end, rows = 1:22,
rule = "number in file1 is found in a specific column of file 2")
Please let me know if this makes sense or if i need to clarify something.
Thanks!

Answer 1

The conditionalFormatting() function embeds active conditional formatting into the excel document but is likely more complicated than you need for a one-time highlight. I'd suggest loading each file into a dataframe, determining which rows contain a matching cell, creating a highlight style (yellow background), loading the file as a workbook object, setting the appropriate rows to the highlight style, and saving the updated workbook object.
The following function is the used to determine which rows have a match. The magrittr package provides the %>% pipes and the data.table package provides the transpose() function.
find_matched_rows <- function(df1, df2) {
require(magrittr)
require(data.table)
# the dataframe object treats each column as a list making it much easier and
# faster to search via column than row. Transpose the original file1 dataframe
# to treat the rows as columns.
df1_transposed <- data.table::transpose(df1)
# assuming that the location of the match in the second file is irrelevant,
# unlist the file2 dataframe so that each value in file1 can be searched in a
# vector
df2_as_vector <- unlist(df2)
# determine which columns contain a match. If one or more matches are found,
# attribute the row as 'TRUE' in the output vector to be used to subset the
# row numbers
match_map <- lapply(df1_transposed,FUN = `%in%`, df2_as_vector) %>%
as.data.frame(stringsAsFactors = FALSE) %>%
sapply(function(x) sum(x) > 0)
# make a vector of row numbers using the logical match_map vector to subset
matched_rows <- seq(1:nrow(df1))[match_map]
return(matched_rows)
}
The following code loads the data, finds the matched rows, applies the highlight, and saves over the original file1.xlsx. The second tst_df1 and tst_df2 provide for an easy way of testing the find_matched_rows() function. As expected, it finds that the 1st and 3rd rows of the first dataframe contain a cell that matches a cell in second dataframe.
# used to ensure that the correct rows are highlighted. the dataframe does not
# include the header as an independent row unlike excel.
file1_header_row <- 1
file2_header_row <- 1
tst_df1 <- openxlsx::read.xlsx("./file1.xlsx",
startRow = file1_header_row)
tst_df2 <- openxlsx::read.xlsx("./file2.xlsx",
startRow = file2_header_row)
#example data for testing
tst_df1 <- data.frame(fname = c("John", "Bob", "Bill"),
lname = c("Smith", "Johnson", "Samson"),
wage = c(10, 15.23, 137.38),
stringsAsFactors = FALSE)
tst_df2 <- data.frame(a = c(10, 34, 284.2),
b = c("Billy", "Bill", "Billy-Bob"),
c = c("Samson", "Johansson", NA),
stringsAsFactors = FALSE)
df_matched_rows <- find_matched_rows(tst_df1, tst_df2)
# any color found in colours() can be used here or hex color beginning with "#"
highlight_style <- openxlsx::createStyle(fgFill = "yellow")
file1_wb <- openxlsx::loadWorkbook(file = "./file1.xlsx")
openxlsx::addStyle(wb = file1_wb,
sheet = 1,
style = highlight_style,
rows = file1_header_row + df_matched_rows,
cols = 1:ncol(tst_df1),
stack = TRUE,
gridExpand = TRUE)
openxlsx::saveWorkbook(wb = file1_wb,
file = "./file1.xlsx",
overwrite = TRUE)