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DATE: 2021-07-05
AUTHOR: John L. Godlee
My partner is visiting some museums and art galleries in the eastern United States in the autumn, to look at Maya, Aztec and Mixtec artefacts that relate to slavery, captivity and forced labour. To find artefacts, she was looking through the online catalogues of each institution, and at the same time wanted to record metadata about the objects to refer back to later. Unfortunately, harvesting the metadata was taking a long time due to all the copying and pasting and manually saving images. I tried to help by writing a few scripts to scrape through the object records online and format the metadata in an organised format.
Some of the institutions provide decent APIs to get artefact data, but others only provide web pages, so I had to use a mixture of different methods to scrape the information.
The institutions I scraped were:
For each of the institutions I was given a txt file of links. I used R to scrape the information as that's what I know best. For institutions who don't have APIs, i.e. Dumbarton Oaks, Museum of Fine Arts Boston, Nasher, Yale Peabody, and Penn Museum, I used {rvest} to parse the html files. For example, for Nasher:
# Packages
library(rvest)
library(dplyr)
# List record URLS
urls <- readLines("links.txt")
# Download pages
lapply(urls, function(x) {
download.file(x, destfile = file.path("html",
gsub("/.*", "", gsub("https://emuseum.nasher.duke.edu/objects/", "", x))))
})
# List html files
html_files <- list.files("html", "*", full.names = TRUE)
# For each file
out_list <- lapply(html_files, function(x) {
x <- read_html(x)
# Get object title
obj_title <- x %>%
html_nodes("div.titleField") %>%
html_nodes("h1") %>%
html_text()
# Get object metadata
obj_labels <- x %>%
html_nodes("span.detailFieldLabel") %>%
html_text() %>%
gsub(":.*", "", .)
obj_values <- x %>%
html_nodes("span.detailFieldValue") %>%
html_text()
# Create dataframe
out <- as.data.frame(t(data.frame(obj_values)))
names(out) <- obj_labels
# Extract image IDs
main_img_id <- x %>%
html_nodes("div.emuseum-img-wrap") %>%
html_nodes("img") %>%
html_attr("src") %>%
gsub("/internal/media/dispatcher/", "", .) %>%
gsub("/.*", "", .) %>%
unique()
sec_img_id <- x %>%
html_nodes("div.secondarymedia-item") %>%
html_nodes("a") %>%
html_attr("data-media-id") %>%
unique()
img_id <- unique(c(main_img_id, sec_img_id))
# Construct image URLs
img_url <- paste0(
"https://emuseum.nasher.duke.edu/internal/media/dispatcher/",
img_id,
"/resize%3Aformat%3Dfull")
# Create filenames
img_filenames <- paste0(out
gemini - kennedy.gemi.dev
Object number`, "_", img_id, ".jpg")
# Download images
if (length(img_url[!is.na(img_url)]) > 1) {
download.file(img_url, destfile = file.path("img", img_filenames),
method = "libcurl")
} else if (length(img_url[!is.na(img_url)]) == 1) {
download.file(img_url, destfile = file.path("img", img_filenames))
}
return(out)
})
# Write metadata to csv
out <- do.call(bind_rows, out_list)
write.csv(out, "all.csv", row.names = FALSE)
I think Princeton probably had the nicest and simplest API to use, while the Smithsonian had the most difficult API. However, the complexity of the Smithsonian API is probably because they have lots of institutions all running the same API, and a very diverse range of records.
To query the API I used {httr}, and to parse the JSON returned by the APIs I used {jsonlite}. Using the Princeton API as an example:
library(httr)
library(jsonlite)
library(dplyr)
base <- "https://data.artmuseum.princeton.edu/objects/"
# Import links
links <- readLines("links.txt")
# Get IDs
ids <- gsub(".*/", "", links)
# For each ID, get record
out_list <- lapply(ids, function(x) {
message(x)
# Get record
resp <- GET(paste0(base, x))
# Parse JSON
resp_parsed <- content(resp, as = "parsed")
# Save JSON
write(content(resp, as = "text"), file.path("json", paste0(x, ".json")))
ifnull <- function(x) {
if (is.null(x)) {
return("NA")
} else {
return(x)
}
}
# Extract description
desc_df <- data.frame(
displayperiod = ifnull(resp_parsed$displayperiod),
displayculture = ifnull(resp_parsed$displayculture),
classification = ifnull(resp_parsed$classification),
daterange = ifnull(resp_parsed$daterange),
description = ifnull(paste(lapply(resp_parsed$texts, function(x) {
x$textentryhtml
}), collapse = "; ")),
accessionyear = ifnull(resp_parsed$accessionyear),
title = ifnull(resp_parsed$titles[[1]]$title),
catalograisonne = ifnull(resp_parsed$catalograisonne),
objectnumber = ifnull(resp_parsed$objectnumber),
objectid = ifnull(resp_parsed$objectid),
department = ifnull(resp_parsed$department),
country = ifnull(resp_parsed$geography[[1]]$country),
locale = ifnull(resp_parsed$geography[[1]]$locale),
region = ifnull(resp_parsed$geography[[1]]$region),
subcontinent = ifnull(resp_parsed$geography[[1]]$subcontinent),
locus = ifnull(resp_parsed$geography[[1]]$locus),
county = ifnull(resp_parsed$geography[[1]]$county),
excavation = ifnull(resp_parsed$geography[[1]]$excavation),
state = ifnull(resp_parsed$geography[[1]]$state),
latitude = ifnull(resp_parsed$geography[[1]]$location$lat),
longitude = ifnull(resp_parsed$geography[[1]]$location$lon),
river = ifnull(resp_parsed$geography[[1]]$location$river),
continent = ifnull(resp_parsed$geography[[1]]$continent),
medium = ifnull(resp_parsed$medium),
dimensions = ifnull(paste(lapply(resp_parsed$dimensionelements, function(x) {
paste(x$type, x$dimension, x$element, x$units, sep = ":")
}), collapse = "; "))
)
img_list <- lapply(resp_parsed$media, function(x) {
c(x$uri, x$id)
})
img_filenames <- paste0(x, "_", lapply(img_list, "[", 2), ".jpg")
img_urls <- paste0(lapply(img_list, "[", 1), "/full/full/0/default.jpg")
if (length(img_list[!is.na(img_list)]) > 1) {
try(download.file(img_urls, destfile = file.path("img", img_filenames),
method = "libcurl"))
} else if (length(img_list[!is.na(img_list)]) == 1) {
try(download.file(img_urls, destfile = file.path("img", img_filenames)))
}
return(desc_df)
})
# Write metadata to csv
out <- do.call(bind_rows, out_list)
write.csv(out, "all.csv", row.names = FALSE)