For kable(), x is an R object, which is typically a matrix or data frame. For kables(), a list with each element being a returned value from kable().

A character string. Possible values are latex, html, pipe (Pandoc's pipe tables), simple (Pandoc's simple tables), and rst. The value of this argument will be automatically determined if the function is called within a knitr document. The format value can also be set in the global option knitr.table.format. If format is a function, it must return a character string.

Maximum number of digits for numeric columns, passed to round(). This can also be a vector of length ncol(x), to set the number of digits for individual columns.

Logical: whether to include row names. By default, row names are included if rownames(x) is neither NULL nor identical to 1:nrow(x).

A character vector of column names to be used in the table.

Column alignment: a character vector consisting of 'l' (left), 'c' (center) and/or 'r' (right). By default or if align = NULL, numeric columns are right-aligned, and other columns are left-aligned. If length(align) == 1L, the string will be expanded to a vector of individual letters, e.g. 'clc' becomes c('c', 'l', 'c'), unless the output format is LaTeX.

The table caption.

The table reference label. By default, the label is obtained from knitr::opts_current$get('label').

A list of arguments to be passed to format() to format table values, e.g. list(big.mark = ',').

Boolean; whether to escape special characters when producing HTML or LaTeX tables. When escape = FALSE, you have to make sure that special characters will not trigger syntax errors in LaTeX or HTML.

A character string for addition HTML table attributes. This is convenient if you simply want to add a few HTML classes or styles. For example, you can put 'class="table" style="color: red"'.

T/F for whether to enable the booktabs format for tables. I personally would recommend you turn this on for every latex table except some special cases.

T/F for whether to use the longtable format. If you have a table that will span over two or more pages, you will have to turn this on.

You probably won't need to adjust this latex option very often. If you are familar with latex tables, this is the optional position for the tabular environment controling the vertical position of the table relative to the baseline of the surrounding text. Possible choices are b, c and t (default).

This is the "real" or say floating position for the latex table environment. The kable only puts tables in a table environment when a caption is provided. That is also the reason why your tables will be floating around if you specify captions for your table. Possible choices are h (here), t (top, default), b (bottom) and p (on a dedicated page).

T (default)/F. Whether to center tables in the table environment.

vertical separator. Default is nothing for booktabs tables but "|" for normal tables.

toprule. Default is hline for normal table but toprule for booktabs tables.

bottomrule. Default is hline for normal table but bottomrule for booktabs tables.

midrule. Default is hline for normal table but midrule for booktabs tables.

By default, in booktabs tables, kable insert an extra space every five rows for clear display. If you don't want this feature or if you want to do it in a different pattern, you can consider change this option. The default is c(”, ”, ”, ”, '\addlinespace'). Also, if you are not using booktabs, but you want a cleaner display, you can change this to ”.

Another latex feature. Short captions for tables

You probably don't need to change this as well. The default setting is to put a table environment outside of tabular if a caption is provided.

Other arguments (see Examples).