Author: Alexander Walker, Philipp Schauberger
Date: 2025-10-30

# Formating with xlsx

#### Alexander Walker, Philipp Schauberger

#### 2025-10-30

## Formatting with writeData and writeDataTable

    ## data.frame to write
    df <- data.frame("Date" = Sys.Date()-0:4,
                     "Logical" = c(TRUE, FALSE, TRUE, TRUE, FALSE),
                     "Currency" = paste("$",-2:2),
                     "Accounting" = -2:2,
                     "hLink" = "https://CRAN.R-project.org/",
                     "Percentage" = seq(-1, 1, length.out=5),
                     "TinyNumber" = runif(5) / 1E9, stringsAsFactors = FALSE)

    class(df$Currency) <- "currency"
    class(df$Accounting) <- "accounting"
    class(df$hLink) <- "hyperlink"
    class(df$Percentage) <- "percentage"
    class(df$TinyNumber) <- "scientific"

    ## Formatting can be applied simply through the write functions
    ## global options can be set to further simplify things
    options("openxlsx.borderStyle" = "thin")
    options("openxlsx.borderColour" = "#4F81BD")

    ## create a workbook and add a worksheet
    wb <- createWorkbook()
    addWorksheet(wb, "writeData auto-formatting")

    writeData(wb, 1, df, startRow = 2, startCol = 2)
    writeData(wb, 1, df, startRow = 9, startCol = 2, borders = "surrounding")
    writeData(wb, 1, df, startRow = 16, startCol = 2, borders = "rows")
    writeData(wb, 1, df, startRow = 23, startCol = 2, borders ="columns")
    writeData(wb, 1, df, startRow = 30, startCol = 2, borders ="all")

    ## headerStyles
    hs1 <- createStyle(fgFill = "#4F81BD", halign = "CENTER", textDecoration = "Bold",
                       border = "Bottom", fontColour = "white")

    writeData(wb, 1, df, startRow = 16, startCol = 10, headerStyle = hs1,
              borders = "rows", borderStyle = "medium")

    ## to change the display text for a hyperlink column just write over those cells
    writeData(wb, sheet = 1, x = paste("Hyperlink", 1:5), startRow = 17, startCol = 14)

    ## writing as an Excel Table

    addWorksheet(wb, "writeDataTable")
    writeDataTable(wb, 2, df, startRow = 2, startCol = 2)
    writeDataTable(wb, 2, df, startRow = 9, startCol = 2, tableStyle = "TableStyleLight9")
    writeDataTable(wb, 2, df, startRow = 16, startCol = 2, tableStyle = "TableStyleLight2")
    writeDataTable(wb, 2, df, startRow = 23, startCol = 2, tableStyle = "TableStyleMedium21")

    openXL(wb) ## opens a temp version

## Use of pre-defined table styles

The ‘tableStyle’ argument in writeDataTable can be any of the predefined tableStyles in Excel.

## Date Formatting

    # data.frame of dates
    dates <- data.frame("d1" = Sys.Date() - 0:4)
    for(i in 1:3) dates <- cbind(dates, dates)
    names(dates) <- paste0("d", 1:8)

    ## Date Formatting
    wb <- createWorkbook()
    addWorksheet(wb, "Date Formatting", gridLines = FALSE)
    writeData(wb, 1, dates) ## write without styling

    ## openxlsx converts columns of class "Date" to Excel dates with the format given by
    getOption("openxlsx.dateFormat", "mm/dd/yyyy")

    ## this can be set via (for example)
    options("openxlsx.dateFormat" = "yyyy/mm/dd")
    ## custom date formats can be made up of any combination of:
    ##   d, dd, ddd, dddd, m, mm, mmm, mmmm, mmmmm, yy, yyyy

    ## numFmt == "DATE" will use the date format specified by the above
    addStyle(wb, 1, style = createStyle(numFmt = "DATE"), rows = 2:11, cols = 1, gridExpand = TRUE)

    ## some custom date format examples
    sty <- createStyle(numFmt = "yyyy/mm/dd")
    addStyle(wb, 1, style = sty, rows = 2:11, cols = 2, gridExpand = TRUE)

    sty <- createStyle(numFmt = "yyyy/mmm/dd")
    addStyle(wb, 1, style = sty, rows = 2:11, cols = 3, gridExpand = TRUE)

    sty <- createStyle(numFmt = "yy / mmmm / dd")
    addStyle(wb, 1, style = sty, rows = 2:11, cols = 4, gridExpand = TRUE)

    sty <- createStyle(numFmt = "ddddd")
    addStyle(wb, 1, style = sty, rows = 2:11, cols = 5, gridExpand = TRUE)

    sty <- createStyle(numFmt = "yyyy-mmm-dd")
    addStyle(wb, 1, style = sty, rows = 2:11, cols = 6, gridExpand = TRUE)

    sty <- createStyle(numFmt = "mm/ dd yyyy")
    addStyle(wb, 1, style = sty, rows = 2:11, cols = 7, gridExpand = TRUE)

    sty <- createStyle(numFmt = "mm/dd/yy")
    addStyle(wb, 1, style = sty, rows = 2:11, cols = 8, gridExpand = TRUE)

    setColWidths(wb, 1, cols = 1:10, widths = 23)

    ## The default date format used in writeData and writeDataTable can be set with:
    options("openxlsx.dateFormat" = "dd/mm/yyyy")
    writeData(wb, "Date Formatting", dates, startRow  = 8, borders = "rows")
    options("openxlsx.dateFormat" = "yyyy-mm-dd")
    writeData(wb, "Date Formatting", dates, startRow  = 15)

    saveWorkbook(wb, "Date Formatting.xlsx", overwrite = TRUE)

## DateTime Formatting

The conversion from POSIX to Excel datetimes is dependent on the timezone you are in. If POSIX values are being written incorrectly, try setting the timezone with (for example)

    Sys.setenv(TZ = "Australia/Sydney")

    dateTimes <- data.frame("d1" = Sys.time() - 0:4*10000)
    for(i in 1:2) dateTimes <- cbind(dateTimes, dateTimes)
    names(dateTimes) <- paste0("d", 1:4)

    ## POSIX Formatting
    wb <- createWorkbook()
    addWorksheet(wb, "DateTime Formatting", gridLines = FALSE)
    writeData(wb, 1, dateTimes) ## write without styling

    ## openxlsx converts columns of class "POSIxt" to Excel datetimes with the format given by
    getOption("openxlsx.datetimeFormat", "yyyy/mm/dd hh:mm:ss")

    ## this can be set via (for example)
    options("openxlsx.datetimeFormat" = "yyyy-mm-dd hh:mm:ss")
    ## custom datetime formats can be made up of any combination of:
    ## d, dd, ddd, dddd, m, mm, mmm, mmmm, mmmmm, yy, yyyy, h, hh, m, mm, s, ss, AM/PM

    ## numFmt == "LONGDATE" will use the date format specified by the above
    long_date_style <- createStyle(numFmt = "LONGDATE")
    addStyle(wb, 1, style = long_date_style, rows = 2:11, cols = 1, gridExpand = TRUE)

    ## some custom date format examples
    sty <- createStyle(numFmt = "yyyy/mm/dd hh:mm:ss AM/PM")
    addStyle(wb, 1, style = sty, rows = 2:11, cols = 2, gridExpand = TRUE)

    sty <- createStyle(numFmt = "hh:mm:ss AM/PM")
    addStyle(wb, 1, style = sty, rows = 2:11, cols = 3, gridExpand = TRUE)

    sty <- createStyle(numFmt = "hh:mm:ss")
    addStyle(wb, 1, style = sty, rows = 2:11, cols = 4, gridExpand = TRUE)

    setColWidths(wb, 1, cols = 1:4, widths = 30)

    ## The default date format used in writeData and writeDataTable can be set with:
    options("openxlsx.datetimeFormat" = "yyyy/mm/dd hh:mm:ss")
    writeData(wb, "DateTime Formatting", dateTimes, startRow  = 8, borders = "rows")

    options("openxlsx.datetimeFormat" = "hh:mm:ss AM/PM")
    writeDataTable(wb, "DateTime Formatting", dateTimes, startRow  = 15)

    saveWorkbook(wb, "DateTime Formatting.xlsx", overwrite = TRUE)
    openXL("DateTime Formatting.xlsx")

## Conditional Formatting

    wb <- createWorkbook()
    addWorksheet(wb, "cellIs")
    addWorksheet(wb, "Moving Row")
    addWorksheet(wb, "Moving Col")
    addWorksheet(wb, "Dependent on 1")
    addWorksheet(wb, "Duplicates")
    addWorksheet(wb, "containsText")
    addWorksheet(wb, "colourScale", zoom = 30)
    addWorksheet(wb, "databar")

    negStyle <- createStyle(fontColour = "#9C0006", bgFill = "#FFC7CE")
    posStyle <- createStyle(fontColour = "#006100", bgFill = "#C6EFCE")

    ## rule applies to all each cell in range
    writeData(wb, "cellIs", -5:5)
    writeData(wb, "cellIs", LETTERS[1:11], startCol=2)
    conditionalFormatting(wb, "cellIs", cols=1, rows=1:11, rule="!=0", style = negStyle)
    conditionalFormatting(wb, "cellIs", cols=1, rows=1:11, rule="==0", style = posStyle)

    ## highlight row dependent on first cell in row
    writeData(wb, "Moving Row", -5:5)
    writeData(wb, "Moving Row", LETTERS[1:11], startCol=2)
    conditionalFormatting(wb, "Moving Row", cols=1:2, rows=1:11, rule="$A1<0", style = negStyle)
    conditionalFormatting(wb, "Moving Row", cols=1:2, rows=1:11, rule="$A1>0", style = posStyle)

    ## highlight column dependent on first cell in column
    writeData(wb, "Moving Col", -5:5)
    writeData(wb, "Moving Col", LETTERS[1:11], startCol=2)
    conditionalFormatting(wb, "Moving Col", cols=1:2, rows=1:11, rule="A$1<0", style = negStyle)
    conditionalFormatting(wb, "Moving Col", cols=1:2, rows=1:11, rule="A$1>0", style = posStyle)

    ## highlight entire range cols X rows dependent only on cell A1
    writeData(wb, "Dependent on 1", -5:5)
    writeData(wb, "Dependent on 1", LETTERS[1:11], startCol=2)
    conditionalFormatting(wb, "Dependent on 1", cols=1:2, rows=1:11, rule="$A$1<0", style = negStyle)
    conditionalFormatting(wb, "Dependent on 1", cols=1:2, rows=1:11, rule="$A$1>0", style = posStyle)

    ## highlight duplicates using default style
    writeData(wb, "Duplicates", sample(LETTERS[1:15], size = 10, replace = TRUE))
    conditionalFormatting(wb, "Duplicates", cols = 1, rows = 1:10, type = "duplicates")

    ## cells containing text
    fn <- function(x) paste(sample(LETTERS, 10), collapse = "-")
    writeData(wb, "containsText", sapply(1:10, fn))
    conditionalFormatting(wb, "containsText", cols = 1, rows = 1:10, type = "contains", rule = "A")

    ## colourscale colours cells based on cell value
    df <- read.xlsx(system.file("extdata", "readTest.xlsx", package = "openxlsx"), sheet = 5)
    writeData(wb, "colourScale", df, colNames=FALSE)  ## write data.frame

    ## rule is a vector or colours of length 2 or 3 (any hex colour or any of colours())
    ## If rule is NULL, min and max of cells is used. Rule must be the same length as style or NULL.
    conditionalFormatting(wb, "colourScale", cols=seq_len(ncol(df)), rows=seq_len(nrow(df)),
       style = c("black", "white"),
       rule = c(0, 255),
       type = "colourScale")

    setColWidths(wb, "colourScale", cols = seq_len(ncol(df)), widths = 1.07)
    setRowHeights(wb, "colourScale", rows = seq_len(nrow(df)), heights = 7.5)

    ## Databars
    writeData(wb, "databar", -5:5)
    conditionalFormatting(wb, "databar", cols = 1, rows = 1:12, type = "databar") ## Default colours

    saveWorkbook(wb, "conditionalFormattingExample.xlsx", TRUE)

    openXL(wb)

## Numeric Formatting

numeric columns styling can be set using the numFmt parameter in createStyle or a default can be set with, for example, options(“openxlsx.numFmt” = “#,#0.00”)

    options("openxlsx.numFmt" = NULL)
    wb <- createWorkbook()
    addWorksheet(wb, "Sheet 1")
    df <- data.frame(matrix(12.987654321, ncol = 7, nrow = 5)) ## data.frame to write
    df[ ,6:7] <- df[ ,6:7]*1E6

    ## Set column 1 class to "comma" to get comma separated thousands
    class(df$X1) <- "comma"

    writeData(wb, 1, df)
    s <- createStyle(numFmt = "0.0")
    addStyle(wb, 1, style = s, rows = 2:6, cols = 2, gridExpand = TRUE)

    s <- createStyle(numFmt = "0.00")
    addStyle(wb, 1, style = s, rows = 2:6, cols = 3, gridExpand = TRUE)

    s <- createStyle(numFmt = "0.000")
    addStyle(wb, 1, style = s, rows = 2:6, cols = 4, gridExpand = TRUE)

    s <- createStyle(numFmt = "#,##0")
    addStyle(wb, 1, style = s, rows = 2:6, cols = 5, gridExpand = TRUE)

    s <- createStyle(numFmt = "#,##0.00")
    addStyle(wb, 1, style = s, rows = 2:6, cols = 6, gridExpand = TRUE)

    s <- createStyle(numFmt = "$ #,##0.00")
    addStyle(wb, 1, style = s, rows = 2:6, cols = 7, gridExpand = TRUE)

    ## set a default number format for numeric columns of data.frames
    options("openxlsx.numFmt" = "$* #,#0.00")
    writeData(wb, 1, x = data.frame("Using Default Options" = rep(2345.1235, 5)), startCol = 9)

    setColWidths(wb, 1, cols = 1:10, widths = 15)

    ## Using default numFmt to round to 2 dp (Any numeric column will be affected)
    addWorksheet(wb, "Sheet 2")
    df <- iris
    df[, 1:4] <- df[1:4] + runif(1)
    writeDataTable(wb, sheet = 2, x = df)
    writeData(wb, sheet = 2, x = df, startCol = 7)
    writeData(wb, sheet = 2, x = df, startCol = 13, borders = "rows")

    ## To stop auto-formatting numerics set
    options("openxlsx.numFmt" = NULL)
    addWorksheet(wb, "Sheet 3")
    writeDataTable(wb, sheet = 3, x = df)

    openXL(wb)