Grob Layout Customization

  • Arguably the most crucial function in grobblR is grob_layout(), which needs to be utilized in order to create the final PDF.
  • grob_layout() reads the grob-row’s and grob-columns within it to know how to layout the page. See the grobblR vignette for information on how it allots space to the grob-rows and grob-columns.
  • There are many ways customize individual grob-rows and grob-columns within the grob-layout, including borders, titles and captions.
library(grobblR)

Borders

  • Within grob_layout(), the grob_row() and grob_col() functions are able to put borders around their contents.
grob_layout(
  grob_row(
    grob_col(1),
    grob_col(border = TRUE, 2)
    ),
  grob_row(
    border = TRUE,
    grob_col(3),
    grob_col(
      border = TRUE,
      grob_row(border = TRUE, grob_col(border = TRUE, 4)),
      grob_row(border = TRUE, grob_col(border = TRUE, 5))
      )
    ),
  height = 100,
  width = 100
  ) %>%
  view_grob()

  • Those borders are customizable. With the border_aes_list argument and the ga_list() function, the user can adjust
    • Which border sides to display (border_sides)
    • The border width (border_width)
    • The border color (border_color)
  • For more information on the aesthetics above, see ?ga_list.
grob_layout(
  grob_row(
    grob_col(1),
    grob_col(
      border = TRUE,
      border_aes_list = ga_list(
        border_color = "red"
        ),
      2
      )
    ),
  grob_row(
    border = TRUE,
    border_aes_list = ga_list(
      border_sides = "top",
      border_width = 5
      ),
    grob_col(3),
    grob_col(
      border = TRUE,
      border_aes_list = ga_list(
        border_sides = "left, bottom",
        border_color = "blue",
        border_width = 4
        ),
      4
      )
    ),
  height = 100,
  width = 100
  ) %>%
  view_grob()

Titles

  • Titles can be added to either grob_layout(), grob_row() or grob_col().
grob_layout(
  title = "grob-layout title",
  grob_row(
    grob_col(1),
    grob_col(title = "grob-column title", 2)
    ),
  grob_row(
    title = "grob-row title",
    grob_col(3),
    grob_col(4)
    )
  ) %>%
  view_grob(height = 100, width = 100)

  • The height of the title can be adjusted by either giving an explicit height in millimeters to the title_height argument, or changing the title height proportion with title_p.
    • title_p corresponds to the proportion of the height allotted to the grob in question which will be given to the title.
    • title_height will override title_p in all cases.
grob_layout(
  title = "grob-layout title",
  title_height = 20,
  grob_row(
    grob_col(1),
    grob_col(
      title = "grob-column title",
      title_p = 0.5,
      2
      )
    ),
  grob_row(
    title = "grob-row title",
    title_height = 10,
    grob_col(3),
    grob_col(4)
    )
  ) %>%
  view_grob(height = 100, width = 100)

  • The aesthetics of the title can be altered as well with the title_aes_list argument and ga_list().
grob_layout(
  title = "grob-layout title",
  title_height = 20,
  title_aes_list = ga_list(
    text_color = "blue",
    border_sides = "bottom"
    ),
  grob_row(
    grob_col(1),
    grob_col(
      title = "grob-column title",
      title_p = 0.5,
      title_aes_list = ga_list(
        font_face = 3,
        text_color = "white",
        background_color = "gray40"
        ),
      2
      )
    )
  ) %>%
  view_grob(height = 100, width = 100)

Captions

  • Everything that applies to titles also applies to captions, as grob_layout(), grob_col() and grob_row() are all equipped with caption, caption_aes_list, caption_p and caption_height arguments.
  • By default, captions are more subtle than titles, but their appearances can be altered however the user wants.
grob_layout(
  caption = "grob-layout caption",
  grob_row(
    grob_col(1),
    grob_col(caption = "grob-column caption", 2)
    ),
  grob_row(
    caption = "grob-row caption",
    grob_col(3),
    grob_col(4)
    )
  ) %>%
  view_grob(height = 100, width = 100)

grob_layout(
  caption = "grob-layout caption",
  caption_height = 20,
  grob_row(
    grob_col(1),
    grob_col(
      caption = "grob-column caption",
      caption_p = 0.5,
      2
      )
    ),
  grob_row(
    caption = "grob-row caption",
    caption_height = 10,
    grob_col(3),
    grob_col(4)
    )
  ) %>%
  view_grob(height = 100, width = 100)

grob_layout(
  caption = "grob-layout caption",
  caption_height = 20,
  caption_aes_list = ga_list(
    text_color = "blue",
    border_sides = "bottom"
    ),
  grob_row(
    grob_col(1),
    grob_col(
      caption = "grob-column caption",
      caption_p = 0.5,
      caption_aes_list = ga_list(
        font_face = 3,
        text_color = "white",
        background_color = "gray40"
        ),
      2
      )
    )
  ) %>%
  view_grob(height = 100, width = 100)

Page Numbers

  • The user can add a page number to the bottom right of the page if he/she wishes, by utilizing the page_number argument within grob_layout().
  • The page number is inserted into the padding of the overall grob-layout.
  • As of now, the aesthetics of the page number is restricted to the default behavior.
grob_layout(
  grob_row(
    grob_col(1),
    grob_col(2)
    ),
  grob_row(
    grob_col(3),
    grob_col(4)
    ),
  page_number = 1
  ) %>%
  view_grob(height = 100, width = 100)

  • FYI - The page number allotted space is more meant for a fully-sized grob-layout (using default grob-layout size) than it is for a 100mm x 100mm sized grob.