Try this out. I changed a few things, including the a slight change to the call to Fill
and limiting the cells included for consideration to those with numeric data. I used lapply
to apply the conditional formatting.
cols <- sample(c(1:5), 1) # number of columns to vary to mimic this unknown
label <- rep(paste0("label ", seq(from=1, to=10)))
mydata <- data.frame(label)
for (i in 1:cols) {
mydata[,i+1] <- sample(c(1:10), 10)
}
# exporting data.frame to excel is easy with xlsx package
sheetname <- "mysheet"
write.xlsx(mydata, "mydata.xlsx", sheetName=sheetname)
file <- "mydata.xlsx"
# but we want to highlight cells if value greater than or equal to 5
wb <- loadWorkbook(file) # load workbook
fo <- Fill(foregroundColor="yellow") # create fill object
cs <- CellStyle(wb, fill=fo) # create cell style
sheets <- getSheets(wb) # get all sheets
sheet <- sheets[[sheetname]] # get specific sheet
rows <- getRows(sheet, rowIndex=2:(nrow(mydata)+1) # get rows
# 1st row is headers
cells <- getCells(rows, colIndex = 3:(cols+3)) # get cells
# in the wb I import with loadWorkbook, numeric data starts in column 3
# and the first two columns are row number and label number
values <- lapply(cells, getCellValue) # extract the values
# find cells meeting conditional criteria
highlight <- "test"
for (i in names(values)) {
x <- as.numeric(values[i])
if (x>=5 & !is.na(x)) {
highlight <- c(highlight, i)
}
}
highlight <- highlight[-1]
lapply(names(cells[highlight]),
function(ii)setCellStyle(cells[[ii]],cs))
saveWorkbook(wb, file)