print to pdf file using grid.table in r - too many rows to fit on one page

Question

I'm trying to output a dataframe of about 40 rows and 5 columns to a .pdf file using grid.table in gridExtra package of R.

However, 40 rows is too long for a page so the .pdf file only shows part of the dataframe. I want to know if I can print two columns on one page so all of the rows show up on one page. Alternatively, I need to know how to print the dataframe over multiple pages. Thanks, John

Answer 1

Try this for drawing table on a pdf file that span multiple pages using gridExtra package:

1. Adjust pdf device aspect ratio

   pdf(file = myfile.pdf, height = 12, width = 26)
   

2. Split the large data frame into chunks and call grid.newpage before drawing a table.

   require(gridExtra)
   pdf(file = myfile.pdf, height = 12, width = 26)
   grid.newpage()
   grid.table(sga_hits[1:38, ], show.rownames = FALSE)
   grid.newpage()
   grid.table(sga_hits[39:75, ], show.rownames = FALSE)
   dev.off()
   

Automate the above as follows:

    require(gridExtra)
    pdf(file = myfile.pdf, height = 12, width = 26)
    total_rows_per_page = 38 
    start_row = 1 

    if(total_rows_per_page > nrow(sga_hits)){
         end_row = nrow(sga_hits)
    }else {
         end_row = total_rows_per_page 
    }    

    for(i in 1:ceiling(nrow(sga_hits)/total_rows_per_page)){

       grid.newpage()   

       grid.table(sga_hits[start_row:end_row, ], show.rownames = FALSE)

       start_row = end_row + 1

       if((total_rows_per_page + end_row) < nrow(sga_hits)){

            end_row = total_rows_per_page + end_row

       }else {

            end_row = nrow(sga_hits)
       }    
    }

    dev.off()

Answer 2

I'd suggest the following strategy: create the tableGrob, query its heights, split the rows to fit each page,

library(gridExtra)
library(grid)
d <- iris[sample(nrow(iris), 187, TRUE),]
tg <- tableGrob(d, rows = seq_len(nrow(d))) 

fullheight <- convertHeight(sum(tg$heights), "cm", valueOnly = TRUE)
margin <- unit(0.51,"in")
margin_cm <- convertHeight(margin, "cm", valueOnly = TRUE)
a4height <- 29.7 - margin_cm
nrows <- nrow(tg)
npages <- ceiling(fullheight / a4height)

heights <- convertHeight(tg$heights, "cm", valueOnly = TRUE) 
rows <- cut(cumsum(heights), include.lowest = FALSE,
            breaks = c(0, cumsum(rep(a4height, npages))))

groups <- split(seq_len(nrows), rows)

gl <- lapply(groups, function(id) tg[id,])

pdf("multipage.pdf", paper = "a4", width = 0, height = 0)
for(page in seq_len(npages)){
  grid.newpage()
  grid.rect(width=unit(21,"cm") - margin,
            height=unit(29.7,"cm")- margin)
  grid.draw(gl[[page]])
}
## alternative to explicit loop:
## print(marrangeGrob(grobs=gl, ncol=1, nrow=1, top=NULL))
dev.off()

Answer 3

One way is to shrink the font the font size and the horizontal/vertical padding.

grid.table(mtcars, gpar.coretext = gpar(fontsize=6), gpar.coltext = gpar(fontsize=6), padding.h=unit(2, "mm"), padding.v=unit(2, "mm"), show.rownames = TRUE)

Answer 4

Implementing viewports from the grid is one potential solution.

A viewport defines a region in the graphics device. It is sometimes useful to define a viewport, then push it and draw inside it. A different viewport may then be pushed and drawn inside of; this method amounts to a simple way to arrange objects on a page.

First, define page and margin sizes.

# Assume total page size is 8.5in x 11in
vp.page <- viewport(x = 0.5, y = 0.5,
                   width = unit(x = 8.5, units = "inches"),
                   height = unit(x = 11, units = "inches"))

# Assume 0.5in margins (i.e., 0.5 left, right, bottom, top)
# This totals 1in for each dimension
vp.marg <- viewport(x = 0.5, y = 0.5,
                    width = (7.5 / 8.5), height = (10 / 11))

Next, Define viewports for each column.

To arrange columns horizontally within a viewport, their x positions will be equally spaced in the interval (0,1).

In the 2 column case, x1 = 0.25 and x2 = 0.75:

# Define the viewport for column 1
vp.col1 <- viewport(x = 0.25, y = 0.5, width = 0.5, height = 1)

# Define the viewport for column 2
vp.col2 <- viewport(x = 0.75, y = 0.5, width = 0.5, height = 1)

Now, actual data is defined. This data will also need to be "grob'd" to be drawn into viewports.

# Assume data is stored as `dat` and has 40 rows
# Grob the data for column 1
col1 <- tableGrob(dat[1:20,], rows = NULL)

# Grob the data for column 2
col2 <- tableGrob(dat[21:40,], rows = NULL)

Now, draw the pdf:

# Initiate the pdf
pdf("results.pdf", height = 11, width = 8.5)
# Push the viewports for page and margin
pushViewport(vp.page); pushViewport(vp.marg)

# Push column 1
pushViewport(vp.col1)
# Draw column 1
grid.draw(col1)

# Return to the previous viewport
upViewport()

# Push the viewport for column 2
pushViewport(vp.col2)
# Draw column 2
grid.draw(col2)

# End the pdf and save it
dev.off()