R officer package: Add slide numbers that reflect current slide position

Question

I'm an avid user of the Reporters and Officer packages and currently trying to transition to Officer for a Powerpoint workflow. I'm using a slide template that includes slide number placeholders in the master.

When using Reporters, I am able to add the slide numbers using doc <-addPageNumber( doc ) and the page numbers reflect the current position each slide has in the deck. I am looking for the same functionality in Officer, and looking for the slide numbers to update appropriately when I move the slides.

When I use ph_with_text(doc, type = "sldNum", str = "slide 1"), I am required to supply a string with a static number or text, and it does not update according to where the slide appears in the deck. For example, if I know my slide will be slide 2, I can enter str = "2", but then the slide number will read as 2 even if I move that slide to the slide 3 position in the presentation.

I tried leaving the string empty with str = "" or with ph_empty(type= "sldNum") but these result in the string "Slide Number" appearing on the slide.

Any help or pointers in the right direction would be appreciated!

Answer 1

I've successfully added page numbers using officer 0.3.4 with a for loop after I'm done with the presentation.

library(officer)
library(magrittr)

my_pres <- read_pptx()  %>% 
  add_slide('Title Only', 'Office Theme') %>%
  ph_with(value = 'Slide 2 Title', location = ph_location_type(type = "title")) %>%
  add_slide('Title Only', 'Office Theme') %>%
  ph_with(value = 'Slide 3 Title', location = ph_location_type(type = 'title')) 

# add slide numbers starting on slide 2

n_slides <- length(my_pres)
for (i_slide in 2:n_slides) {
  my_pres <- my_pres %>%
    on_slide(index = i_slide) %>%
    ph_with(value = i_slide, location = ph_location_type('sldNum'))
}