alter_at: Alter aesthetics / structures at certain areas of a grob...
In grobblR: Creating Flexible, Reproducible 'PDF' Reports

Description Usage Arguments Value Examples

Flexibly alter the aesthetic / structure of a grob matrix object at specific points of the data.frame/matrix.

alter_at(
  grob_object,
  .f = NULL,
  ...,
  columns = NULL,
  rows = NULL,
  data = NULL,
  structure = NULL,
  aesthetic = NULL,
  group = NULL
)

`grob_object`	The R6 grob object class initialized by `grob_matrix`.
`.f`	A quosure style lambda `~ fun(.)`, which the user wants to apply to the specific subset of cells.
`...`	Logical predicates defined in terms of the variables in the initial data frame / matrix, or if the user provides a new data.frame to evaluate via `data`. Multiple conditions are combined with `&`. Only rows where the condition evaluates to TRUE are evaluated. If no logical predicates provided, then the entire columns will be altered.
`columns`	A character vector of column names, or numeric column indices, of the initial data.frame/matrix, or `data` if it is provided, the user wishes to alter.
`rows`	A numeric vector of row indices, of the initial data.frame/matrix, or `data` if it is provided, the user wishes to alter. Ignored if the user is altering a structure and not an aesthetic.
`data`	A separate data.frame/matrix of the same dimensions as the initial data.frame/matrix which the `.f` function and any filters will be applied to. Must match the dimensions of the subset of the initial data.frame/matrix the user is attempting to alter. Ignored if the user is altering a structure and not an aesthetic.
`structure`	Which structure the user wants to make alterations to. If left `NULL` and `aesthetic` is left `NULL`, the function will look for the most previous altered structure, either via `add_structure`, or a previous application of `alter_at`. View the documentation of `add_structure` for a list of accepted structures
`aesthetic`	Which aesthetic the user wants to make alterations to. If left `NULL` and `structure` is left `NULL`, the function will look for the most previous altered aesthetic, either via `add_aesthetic`, or a previous application of `alter_at`. View the documentation of `add_aesthetic` for a list of accepted aesthetics.
`group`	Which group of elements the user wants to make alterations to. If left `NULL`, the function will look for the most previous altered group, either via `add_aesthetic`, or a previous application of `alter_at`.

The R6 grob matrix object class with its aesthetic / structure properties altered.

df = data.frame(var1 = c(5, 14, 6, 10), var2 = c(3, 30, 17, 7))
df %>%
  grob_matrix() %>%
  add_aesthetic(aesthetic = 'text_color', group = 'cells', value = 'red') %>%
  alter_at(
    .f = ~ 'blue',
    abs(var2 - var1) > 1
    ) %>%
  view_grob()

test_function = function(x) ifelse(x > 15, 2, 1)

df %>%
  grob_matrix() %>%
  alter_at(
    .f = ~ test_function(.),
    aesthetic = 'font_face',
    group = 'cells'
    ) %>%
  view_grob()
  
df %>%
  grob_matrix() %>%
  add_structure("column_widths_p", 1) %>%
  alter_at(
    .f = ~ 2,
    columns = 1
    ) %>%
  view_grob()