# jst_get_total_pages: Calculate total pages In jstor: Read Data from JSTOR/DfR

 jst_get_total_pages R Documentation

## Calculate total pages

### Description

This function is a simple helper to calculate the total number of pages of an article.

### Usage

``````jst_get_total_pages(first_page, last_page, page_range, quietly = FALSE)
``````

### Arguments

 `first_page` The first page of an article (numeric). `last_page` The last page of an article (numeric). `page_range` The page range of an article (character). `quietly` Sometimes page ranges contain roman numerals like `xiv`. These are not recognized, return `NA` and raise a warning. If set to `TRUE`, this warning not raised.

### Details

This function deals with four cases:

• if all three arguments are missing, NA is returned.

• if page_range is supplied, the number of pages is calculated from it.

• if only the first page is supplied, NA is returned.

• if first and last page are supplied, the number of pages is calculated as `last_page - first_page + 1`.

The algorithm to parse page ranges works as follows: A typical page range is `⁠1-10, 200⁠` where the article starts at page 1, ends at page 10, and has an erratum at page 200. For this case, the range is calculated as `range + single_page`, as in`(10 - 1 + 1) + 1 = 11`. Sometimes multiple ranges are given: `⁠1-10, 11-20⁠`. For those cases all ranges are summed: `(10 - 1 + 1) + (20 - 11 + 1) = 20`. Another specification for multiple ranges is `1-10+11-20`, which is treated similarly.

### Value

A vector with the calculated total pages.

### Examples

``````# calculate pages from first and last page
first_pages <- sample(30:50, 10)
last_pages <- first_pages + sample(5:20, 10)
page_ranges <- rep(NA_character_, 10)

jst_get_total_pages(first_pages, last_pages, page_ranges)

# get pages from page range
jst_get_total_pages(NA_real_, NA_real_, "51 - 70")
jst_get_total_pages(NA_real_, NA_real_, "51 - 70, 350")
jst_get_total_pages(NA_real_, NA_real_, "350, 51 - 70")
jst_get_total_pages(NA_real_, NA_real_, "51 - 70, 80-100")
jst_get_total_pages(NA_real_, NA_real_, "51-70+350")
``````

jstor documentation built on Aug. 16, 2023, 5:09 p.m.