CODEWITHSUNDEEP
rpdfpngmultipagemagick
Nova
Nova

Reputation: 5891

Convert .png to multi-page pdf using Magick in R

I have a directory full of 100 .png images I'd like to convert to pdf.

The images are exactly the size I want the pdf to be.

I can create a multi-page pdf using magick "manually" like this:

library(magick)

img1 <- image_read("image1.png")
img2 <- image_read("image2.png")

image_write(c(img1, img2), format = "pdf", "check.pdf")

But I'm having trouble getting the image_write command to accept a vector of filenames to automate this process. For example, I'd like to make a 100-page pdf from the .png images in my directory "test":

all_images <- list.files("test")

I thought that purrr might help but no luck:

library(purrr)

image_write(map(all_images, image_read), format = "pdf", "check.pdf")

Any ideas?

Upvotes: 4

Views: 5868

Answers (2)

andschar
andschar

Reputation: 3993

magick::image_*() functions are vectorized. So you can do:

dir = '/path/to/dir'
fl = list.files(dir, full.names = TRUE, pattern = '.png')
# magick
img = image_read(fl) # read from vector of paths
img2 = image_append(img, stack = TRUE) # places pics above one another

image_write(img2, file.path(dir, 'check.pdf'))

This places the images above one another, yet not on single pages.

Upvotes: 2

Yifu Yan
Yifu Yan

Reputation: 6116

You need to concatenate different "magick-image objects using c.

It's the same as doing c(img1,img2,img3,...)

all_images_1 <- purrr::reduce(
    purrr::map(all_images,image_read),
    c
)

image_write(all_images_1 , format = "pdf", "check.pdf")

Upvotes: 4

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