Function to color cells in rhandsontable along with code to use it

color_cell_renderer_rhandsontable.R

# This generates a string that will be used within the render fxn
# in handsontable(). The string needs two parameters for this fxn to work:
# 1. A list of columns: so a list named col_highlight, with keys:
# colhighlight1, colhighlight2 ... up to vars_len. Each key has a corresponding
# value which is the column number within the handsontable to color
# 1. A list of lists of rows: so a list named row_highlight, with keys:
# rowhighlight1, row_highlight2 ... up to vars_len. Each key has a corresponding
# value which is a vector of row numbers within the handsontable to color 

# The highlighted cells are the cells represented by colhighight1, rowhighlight1,...
# colhighlight2 (length 1), rowhighlight2 (length x), up to vars_len. 

# vars_len is a range of 1:length(col_highlight)

generate_failed_cell_renderer <- function(vars_len, 
                                          highlight_color = '#FFA2A2') {
  col_row_init_str <-  paste(sprintf(
    "hcols%s = instance.params.col_highlight.col_highlight%s 
    hcols%s = hcols%s instanceof Array ? hcols%s : [hcols%s] 
    hrows%s = instance.params.row_highlight.row_highlight%s 
    hrows%s = hrows%s instanceof Array ? hrows%s : [hrows%s]", vars_len,
    vars_len, vars_len, vars_len, vars_len, vars_len, 
    vars_len, vars_len, vars_len, vars_len,
    vars_len, vars_len), collapse = "\n") # dont forget to sep by newline
  
  # if statements generated to highlight each failed cell
  if_statement_str <- paste(sprintf(
    "if ((instance.params && hcols%s.includes(col)) & (instance.params && hrows%s.includes(row))) 
    td.style.background = '%s';", vars_len, vars_len,
    highlight_color), collapse = "\n")
  # overall function used to render highlights
  render_cell_detect <- paste0( "
                                function(instance, td, row, col, prop, value, cellProperties) {
                                Handsontable.renderers.NumericRenderer.apply(this, arguments);
                                if (instance.params) { 
                                ", col_row_init_str,  " 
                                } 
                                ", if_statement_str, " 
                                }")
      return(render_cell_detect)
}

## To use it ##
col_highlight = list(colhighlight1 = 1,
                     colhighlight2 = 2)
row_highlight = list(rowhighlight1 = c(0,1,2),
                     rowhighlight2 = c(2,3))
hot_table <- as.data.frame(
               list(
                 row1 = c(1,2,3,4,5),
                 row2 = c(5,4,3,2,1),
                 row3 = c(7,8,9,10,11),
                 row4 = c(0,1,2,3,4)
                 )
               )
               
vars_len <- 1:length(col_highlight)
render_cell_detect <- generate_failed_cell_renderer(vars_len, 
                                          highlight_color = '#FFA2A2') 
rhandsontable::rhandsontable(
        row_highlight = row_highlight,
        col_highlight = col_highlight,
        as.data.frame(hot_table),
        height = 750) %>%
        # highlight failed cells
        rhandsontable::hot_cols(renderer = render_cell_detect)