How to combine text that has spilled over multiple rows in R

I scraped a PDF in R using tabulizer and saw that multi-line text often spilled over into multiple rows, like so:

              item quantity price
1   PURCHASE ORDER       NA    NA
2    ITEM CODE ABC       NA    NA
3  1 Computer soft        3 10.99
4             ware       NA    NA
5         2 Mathem        2  8.50
6 atics curriculum       NA    NA
7  and calculators       NA    NA

I would like to combine the text across multiple rows into a limited number of rows, so it looks like this:

  item                                    quantity price
1 PURCHASE ORDER ITEM CODE ABC                NA    NA  
2 1 Computer software                           3 10.99
3 2 Mathematics curriculum and calculators      2  8.5 

Here is the code for recreating these tibbles:

#Messy tibble
item <- c("PURCHASE ORDER", "ITEM CODE ABC", "1 Computer soft", "ware", "2 Mathem", "atics curriculum", "and calculators")
quantity <- c(NA, NA, 3, NA, 2, NA, NA)
price <- c(NA, NA, 10.99, NA, 8.50, NA, NA)
df <- data.frame(item, quantity, price)
df

#Clean tibble
item <- c("PURCHASE ORDER ITEM CODE ABC", "1 Computer software", "2 Mathematics curriculum and calculators")
quantity <- c(NA, 3, 2)
price <- c(NA, 10.99, 8.50)
df <- data.frame(item, quantity, price)
df

You could identify the groups by those that have missing values on quantity and price. Then, make unique group identifiers for the text that will go together. Finally, you can paste the text together and take the values of quantity and price that belong to the first observation in each group:

library(dplyr)
item <- c("PURCHASE ORDER", "ITEM CODE ABC", "1 Computer soft", "ware", "2 Mathem", "atics curriculum", "and calculators")
quantity <- c(NA, NA, 3, NA, 2, NA, NA)
price <- c(NA, NA, 10.99, NA, 8.50, NA, NA)
df <- data.frame(item, quantity, price)
df
#>               item quantity price
#> 1   PURCHASE ORDER       NA    NA
#> 2    ITEM CODE ABC       NA    NA
#> 3  1 Computer soft        3 10.99
#> 4             ware       NA    NA
#> 5         2 Mathem        2  8.50
#> 6 atics curriculum       NA    NA
#> 7  and calculators       NA    NA

df %>% 
  mutate(grp = ifelse(is.na(quantity) & is.na(price) & !row_number() == 1, 0, 1),
         grp = cumsum(grp)) %>%
  group_by(grp) %>% 
  reframe(item = paste(item, collapse=" "), 
            across(c(quantity, price), first)) %>%
  select(-grp)
#> # A tibble: 3 × 3
#>   item                                      quantity price
#>   <chr>                                        <dbl> <dbl>
#> 1 PURCHASE ORDER ITEM CODE ABC                    NA  NA  
#> 2 1 Computer soft ware                             3  11.0
#> 3 2 Mathem atics curriculum and calculators        2   8.5

^{Created on 2023-06-21 with reprex v2.0.2}

Here is one option to tidy up your data:

Note: IMHO the first two rows ("PURCHASE ....") reflect the column name and should be dropped.

library(dplyr, warn=FALSE)
library(tidyr)
library(stringr)

df |> 
  mutate(no = as.numeric(str_extract(item, "^\\d+"))) |> 
  fill(no) |> 
  replace_na(list(no = 0)) |> 
  group_by(no) |> 
  summarise(across(everything(), \(x) paste0(x[!is.na(x)], collapse = " "))) |> 
  select(-no)
#> # A tibble: 3 × 3
#>   item                                      quantity price  
#>   <chr>                                     <chr>    <chr>  
#> 1 PURCHASE ORDER ITEM CODE ABC              ""       ""     
#> 2 1 Computer soft ware                      "3"      "10.99"
#> 3 2 Mathem atics curriculum and calculators "2"      "8.5"

From your post, it is not clear if quantity or price will have a value for the same line item. So, I simply took the sum, you can decide how to aggregate these lines.

library(dplyr)

df |>
  mutate(line = cumsum(grepl("^\\d+", item))) |>
  summarize(item = paste(item, collapse = " "),
            across(c(quantity, price), ~if(any(!is.na(.x))) sum(.x, na.rm = T) else NA),
            .by = line) |>
  select(-line)

The first "line" does not have any values nor does it start with a digit like the others. As mentioned by @stefan if these are some type of header that you want to exclude, you can simplify the across statement to across(c(quantity, price), na.omit) and change summarize to reframe.

Output

                                       item quantity price
1              PURCHASE ORDER ITEM CODE ABC       NA    NA
2                      1 Computer soft ware        3 10.99
3 2 Mathem atics curriculum and calculators        2  8.50