R: Outputting HTML tables

htmlTable {htmlTable} | R Documentation

## Outputting HTML tables

### Description

This is a function for outputting a more advanced table than what xtable, ztable, or knitr's `kable()` allows. It's aim is to provide the Hmisc `latex()` colgroup and rowgroup functions in HTML. The html-output is designed for maximum compatibility with LibreOffice/OpenOffice.

### Usage

    htmlTable(x, ...)

    ## Default S3 method:
    htmlTable(x, header, rnames, rowlabel, caption, tfoot, label,
      rgroup, n.rgroup, cgroup, n.cgroup, tspanner, n.tspanner, total,
      align = paste(rep("c", ncol(x)), collapse = ""),
      align.header = paste(rep("c", ncol(x)), collapse = ""), align.cgroup,
      css.rgroup = "font-weight: 900;", css.rgroup.sep = "",
      css.tspanner = "font-weight: 900; text-align: left;",
      css.tspanner.sep = "border-top: 1px solid #BEBEBE;",
      css.total = "border-top: 1px solid #BEBEBE; font-weight: 900;",
      css.cell = "", css.cgroup = "", css.class = "gmisc_table",
      css.table = "margin-top: 1em; margin-bottom: 1em;",
      pos.rowlabel = "bottom", pos.caption = "top", col.rgroup = "none",
      col.columns = "none", padding.rgroup = "&nbsp;&nbsp;",
      padding.tspanner = "", ctable = TRUE,
      compatibility = getOption("htmlTableCompat", "LibreOffice"),
      cspan.rgroup = "all", escape.html = FALSE, ...)

    ## S3 method for class 'htmlTable'
    knit_print(x, ...)

    ## S3 method for class 'htmlTable'
    print(x, useViewer, ...)

### Arguments

`x` | The matrix/data.frame with the data. For the `print` and `knit_print` it takes a string of the class `htmlTable` as `x` argument.
`...` | Passed on to `print.htmlTable` function and any argument except the `useViewer` will be passed on to the `cat` functions arguments.
`header` | A vector of character strings specifying column header, defaulting to `colnames(x)`
`rnames` | Default rownames are generated from `rownames(x)`. If you provide `FALSE` then it will skip the rownames. Note: For `data.frames` if you do `rownames(my_dataframe) <- NULL` it still has rownames. Thus you need to use `FALSE` if you want to surpress rownames for `data.frames`.
`rowlabel` | If the table has rownames or `rnames`, rowlabel is a character string containing the column heading for the `rnames`.
`caption` | Adds a table caption.
`tfoot` | Adds a table footer (uses the `<tfoot>` html element). The output is run through `txtMergeLines` simplifying the generation of multiple lines.
`label` | A text string representing a symbolic label for the table for referencing as an anchor. All you need to do is to reference the table, for instance `<a href="#anchor_name">see table 2</a>`. This is known as the element's id attribute, i.e. table id, in HTML linguo, and should be unique id for an HTML element in contrast to the `css.class` element attribute.
`rgroup` | A vector of character strings containing headings for row groups. `n.rgroup` must be present when `rgroup` is given. See detailed description in section below.
`n.rgroup` | An integer vector giving the number of rows in each grouping. If `rgroup` is not specified, `n.rgroup` is just used to divide off blocks of rows by horizontal lines. If `rgroup` is given but `n.rgroup` is omitted, `n.rgroup` will default so that each row group contains the same number of rows. If you want additional rgroup column elements to the cells you can sett the "add" attribute to `rgroup` through `attr(rgroup, "add")`, see below explaining section.
`cgroup` | A vector or a matrix of character strings defining major column header. The default is to have none. These elements are also known as column spanners. If you want a column not to have a spanner then put that column as "". If you pass cgroup and `n.crgroup` as matrices you can have column spanners for several rows. See cgroup section below for details.
`n.cgroup` | An integer vector or matrix containing the number of columns for which each element in cgroup is a heading. For example, specify `cgroup=c("Major_1","Major_2")`, `n.cgroup=c(3,3)` if `"Major_1"` is to span columns 1-3 and `"Major_2"` is to span columns 4-6. `rowlabel` does not count in the column numbers. You can omit `n.cgroup` if all groups have the same number of columns. If the n.cgroup is one less than the number of columns in the matrix/data.frame then it automatically adds those.
`tspanner` | The table spanner is somewhat of a table header that you can use when you want to join different tables with the same columns.
`n.tspanner` | An integer vector with the number of rows in the original matrix that the table spanner should span.
`total` | The last row is sometimes a row total with a border on top and bold fonts. Set this to `TRUE` if you are interested in such a row. If you want a total row at the end of each table spanner you can set this to `"tspanner"`.
`align` | A character strings specifying column alignments, defaulting to `paste(rep('c',ncol(x)),collapse='')` to center. Valid alignments are l = left, c = center and r = right. You can also specify `align='c|c'` and other LaTeX tabular formatting. If you want to set the alignment of the rownames this string needst to be `ncol(x) + 1`, otherwise it automatically pads the string with a left alignment for the rownames.
`align.header` | A character strings specifying alignment for column header, defaulting to centered, i.e. `paste(rep('c',ncol(x)),collapse='')`.
`align.cgroup` | The justification of the `cgroups`
`css.rgroup` | CSS style for the rgorup, if different styles are wanted for each of the rgroups you can just specify a vector with the number of elements
`css.rgroup.sep` | The line between different rgroups. The line is set to the TR element of the lower rgroup, i.e. you have to set the border-top/padding-top etc to a line with the expected function. This is only used for rgroups that are printed. You can specify different separators if you give a vector of rgroup - 1 length (this is since the first rgroup doesn't have a separator).
`css.tspanner` | The CSS style for the table spanner
`css.tspanner.sep` | The line between different spanners
`css.total` | The css of the total row
`css.cell` | The css.cell element allows you to add any possible CSS style to your table cells. See section below for details.
`css.cgroup` | The same as `css.class` but for cgroup formatting.
`css.class` | The html CSS class for the table. This allows directing html formatting through CSS directly at all instances of that class. Note: unfortunately the CSS is frequently ignored by word processors. This option is mostly inteded for web-presentations.
`css.table` | You can specify the the style of the table-element using this parameter
`pos.rowlabel` | Where the rowlabel should be positioned. This value can be `"top"`, `"bottom"`, `"header"`, or a integer between `1` and `nrow(cgroup) + 1`. The options `"bottom"` and `"header"` are the same, where the row label is presented at the same level as the header.
`pos.caption` | Set to `"bottom"` to position a caption below the table instead of the default of `"top"`.
`col.rgroup` | Alternating colors (zebra striping/banded rows) for each `rgroup`; one or two colors is recommended and will be recycled.
`col.columns` | Alternating colors for each column.
`padding.rgroup` | Generally two non-breakings spaces, i.e. `&nbsp;&nbsp;`, but some journals only have a bold face for the rgroup and leaves the subelements unindented.
`padding.tspanner` | The table spanner is usually without padding but you may specify padding similar to `padding.rgroup` and it will be added to all elements, including the rgroup elements. This allows for a 3-level hierarchy if needed.
`ctable` | If the table should have a double top border or a single a' la LaTeX ctable style
`compatibility` | Is default set to `LibreOffice` as some settings need to be in old html format as Libre Office can't handle some commands such as the css caption-alignment. Note: this option is not yet fully implemented for all details, in the future I aim to generate a html-correct table and one that is aimed at Libre Office compatibility. Word-compatibility is difficult as Word ignores most settings and destroys all layout attempts (at least that is how my 2010 version behaves). You can additinally use the `options(htmlTableCompat = "html")` if you want a change to apply to the entire document.
`cspan.rgroup` | The number of columns that an `rgroup` should span. It spans by default all columns but you may want to limit this if you have column colors that you want to retain.
`escape.html` | logical: should HTML characters be escaped? Defaults to FALSE.
`useViewer` | If you are using RStudio there is a viewer thar can render the table within that is envoced if in `interactive` mode. Set this to `FALSE` if you want to remove that functionality. You can also force the function to call a specific viewer by setting this to a viewer function, e.g. `useViewer = utils::browseURL` if you want to override the default RStudio viewer. Another option that does the same is to set the `options(viewer=utils::browseURL)` and it will default to that particular viewer (this is how RStudio decides on a viewer). Note: If you want to force all output to go through the `cat()` the set `options(htmlTable.cat = TRUE)`.

### Value

`string` Returns a string of class htmlTable

### Multiple rows of column spanners `cgroup`

If you want to have a column spanner in multiple levels you can set the `cgroup` and `n.cgroup` arguments to matrices. If the different levels have different number of elements you need to set the ones that lack elements to NA. For instance `cgroup = rbind(c("first", "second", NA), c("a", "b", "c"))`. And the corresponding n,cgroup would be `n.cgroup = rbind(c(1, 2, NA), c(2, 1, 2))`. for a table consisting of 5 columns. The "first" spans the first two columns, the "second" spans the last three columns, "a" spans the first two, "b" the middle column, and "c" the last two columns.

### The `rgroup` argument

The rgroup allows you to smoothly group rows. Each row within a group receives an indention of two blank spaces and are grouped with their corresponing rgroup element. The `sum(n.rgroup)` should always be equal or less than the matrix rows. If less then it will pad the remaining rows with either an empty rgroup, i.e. an "" or if the rgroup is one longer than the n.rgroup the last n.rgroup element will be calculated through `nrow(x) - sum(n.rgroup)` in order to make the table generating smoother.

### The add attribute to `rgroup`

You can now have an additional element at the rgroup level by specifying the `attr(rgroup, 'add')`. The value can either be a `vector`, a `list`, or a `matrix`. See `vignette("general", package = "htmlTable")` for examples.

- A `vector` of either equal number of rgroups to the number of rgroups that aren't empty, i.e. `rgroup[rgroup != ""]`. Or a named vector where the name must correspond to either an rgroup or to an rgroup number.

- A `list` that has exactly the same requirements as the vector. In addition to the previous we can also have a list with column numbers within as names within the list.

- A `matrix` with the dimensiont `nrow(x) x ncol(x)` or `nrow(x) x 1` where the latter is equivalent to a named vector. If you have `rownames` these will resolve similarly to the names to the `list`/`vector` arguments. The same thing applies to `colnames`.

### Important knitr-note

This funciton will only work with knitr outputting html, i.e. markdown mode. As the function returns raw html-code the compatibility with non-html formatting is limited, even with pandoc.

Thanks to the the `knit_print` and the `asis_output` the `results='asis'` is no longer needed except within for-loops. If you have a knitr-chunk with a for loop and use `print()` to produce raw html you must set the chunk option `results='asis'`. `Note`: the print-function relies on the `interactive()` function for determining if the output should be sent to a browser or to the terminal. In vignettes and other directly knitted documents you may need to either set `useViewer = FALSE` alternatively set `options(htmlTable.cat = TRUE)`.

### RStudio's notebook

RStudio has an interactive notebook that allows output directly into the document. In order for the output to be properly formatted it needs to have the `class` of `html`. The `htmlTable` tries to identify if the environment is a notebook document (uses the rstudio api and identifies if its a file with and 'Rmd' file ending or if ther is an element with ‘html_notebook'). If you don’t want this behaviour you can remove it using the 'options(htmlTable.skip_notebook = TRUE)'

### Table counter

If you set the option table_counter you will get a Table 1,2,3 etc before each table, just set `options(table_counter=TRUE)`. If you set it to a number then that number will correspond to the start of the table_counter. The `table_counter` option will also contain the number of the last table, this can be useful when referencing it in text. By setting the option `options(table_counter_str = "<b>Table %s:</b> ")` you can manipulate the counter table text that is added prior to the actual caption. Note, you should use the `sprintf` `%s` instead of `%d` as the software converts all numbers to characters for compatibility reasons. If you set `options(table_counter_roman = TRUE)` then the table counter will use Roman numumerals instead of Arabic.

### The `css.cell` argument

The `css.cell` parameter allows you to add any possible CSS style to your table cells. `css.cell` can be either a vector or a matrix.

If `css.cell` is a vector, it's assumed that the styles should be repeated throughout the rows (that is, each element in css.cell specifies the style for a whole column of 'x').

In the case of `css.cell` being a matrix of the same size of the `x` argument, each element of `x` gets the style from the corresponding element in css.cell. Additionally, the number of rows of `css.cell` can be `nrow(x) + 1` so the first row of of `css.cell` specifies the style for the header of `x`; also the number of columns of `css.cell` can be `ncol(x) + 1` to include the specification of style for row names of `x`.

Note that the `text-align` CSS field in the `css.cell` argument will be overriden by the `align` argument.

### Empty dataframes

An empty dataframe will result in a warning and output an empty table, provided that rgroup and n.rgroup are not specified. All other row layout options will be ignored.

### Browsers and possible issues

Copy-pasting: As you copy-paste results into Word you need to keep the original formatting. Either right click and choose that paste option or click on the icon appearing after a paste. Currently the following compatibitilies have been tested with MS Word 2013:

- Internet Explorer (v. 11.20.10586.0) Works perfectly when copy-pasting into Word

- RStudio (v. 0.99.448) Works perfectly when copy-pasting into Word. Note: can have issues with multiline cgroups - see bug

- Chrome (v. 47.0.2526.106) Works perfectly when copy-pasting into Word. Note: can have issues with multiline cgroups - see bug

- Firefox (v. 43.0.3) Works poorly - looses font-styling, lines and general feel

- Edge (v. 25.10586.0.0) Works poorly - looses lines and general feel

Direct word processor opening: Opening directly in LibreOffice or Word is no longer recommended. You get much prettier results using the cut-and-paste option.

Note that when using complex cgroup alignments with multiple levels not every browser is able to handle this. For instance the RStudio webkit browser seems to have issues with this and a bug has been filed.

As the table uses html for rendering you need to be aware of that headers, rownames, and cell values should try respect this for optimal display. Browsers try to compensate and frequently the tables still turn out fine but it is not advized. Most importantly you should try to use `&lt;` instead of `<` and `&gt;` instead of `>`. You can find a complete list of html characters here.

### See Also

`txtMergeLines`, `latex`

Other table functions: `tblNoLast`, `tblNoNext`

### Examples

    # Store all output into a list in order to
    # output everything at once at the end
    all_tables <- list()

    # A simple output
    output <- matrix(1:4,
                     ncol=2,
                     dimnames = list(list("Row 1", "Row 2"),
                                     list("Column 1", "Column 2")))
    htmlTable(output) ->
      all_tables[["Basic table"]]

    # An advanced output
    output <-
      matrix(ncol=6, nrow=8)

    for (nr in 1:nrow(output)){
      for (nc in 1:ncol(output)){
        output[nr, nc] <-
          paste0(nr, ":", nc)
      }
    }

    htmlTable(output, align="r",
              header =  paste(c("1st", "2nd",
                                "3rd", "4th",
                                "5th", "6th"),
                              "hdr"),
              rnames = paste(c("1st", "2nd",
                               "3rd",
                               paste0(4:8, "th")),
                             "row"),
              rgroup = paste("Group", LETTERS[1:3]),
              n.rgroup = c(2,4,nrow(output) - 6),
              cgroup = rbind(c("", "Column spanners", NA),
                             c("", "Cgroup 1", "Cgroup 2&dagger;")),
              n.cgroup = rbind(c(1,2,NA),
                               c(2,2,2)),
              caption="Basic table with both column spanners (groups) and row groups",
              tfoot="&dagger; A table footer commment",
              cspan.rgroup = 2,
              col.columns = c(rep("none", 2),
                              rep("#F5FBFF", 4)),
              col.rgroup = c("none", "#F7F7F7"),
              css.cell = "padding-left: .5em; padding-right: .2em;") ->
      all_tables[["Advanced table"]]

    # An advanced empty table
    output <- matrix(ncol = 6,
                     nrow = 0)

    htmlTable(output, align="r",
              header =  paste(c("1st", "2nd",
                                "3rd", "4th",
                                "5th", "6th"),
                              "hdr"),
              cgroup = rbind(c("", "Column spanners", NA),
                             c("", "Cgroup 1", "Cgroup 2&dagger;")),
              n.cgroup = rbind(c(1,2,NA),
                               c(2,2,2)),
              caption="Basic empty table with column spanners (groups) and ignored row colors",
              tfoot="&dagger; A table footer commment",
              cspan.rgroup = 2,
              col.columns = c(rep("none", 2),
                              rep("#F5FBFF", 4)),
              col.rgroup = c("none", "#F7F7F7"),
              css.cell = "padding-left: .5em; padding-right: .2em;") ->
      all_tables[["Empty table"]]

    # An example of how to use the css.cell for header styling
    simple_output <- matrix(1:4, ncol=2)
    htmlTable(simple_output,
              header = LETTERS[1:2],
              css.cell = rbind(rep("background: lightgrey; font-size: 2em;", times=ncol(simple_output)),
                               matrix("", ncol=ncol(simple_output), nrow=nrow(simple_output)))) ->
      all_tables[["Header formatting"]]

    concatHtmlTables(all_tables)
    # See vignette("tables", package = "htmlTable")
    # for more examples

[Package htmlTable version 1.12 Index]