Add summary area to grid

## Arguments

- grid
A table created with

`datagrid()`

.- columns
Name of column (variable name) for which to add a summary.

- stat
Statistic to display:

`"sum"`

,`"min"`

,`"max"`

or`"avg"`

. Can be several values.- digits
Number of digits to display.

- label
Label to display next to statistic.

- sep
Separator between several statistics.

- position
The position of the summary area:

`"bottom"`

or`"top"`

.- height
The height of the summary area.

- js_function
JavaScript function to compute the statistic you want. Function should have one argument, it will be the values of the column. If used,

`stat`

,`digits`

,`label`

and`sep`

will be ignored.

## Examples

```
library(toastui)
# Add a line with sum of column
datagrid(ps3_games[, c(1, 5, 6, 7, 8)], colwidths = "guess") %>%
grid_summary(
column = "NA_Sales",
stat = "sum"
)
# Do that for several columns
datagrid(ps3_games[, c(1, 5, 6, 7, 8)], colwidths = "guess") %>%
grid_summary(
column = c("NA_Sales", "EU_Sales", "JP_Sales", "Other_Sales"),
stat = "sum",
label = "Total: "
)
```