To aid users in what can be done with rdpla
, the following is one example.
Use case:
Search for all photos of churches and make a visualization through time and facet by other factors
library("rdpla")
library("data.table")
library("lubridate")
To get all data for subject:churches
and of type=image
we'd need to do about 100
requests of size 500 records, but we'll just do one that so the example runs quickly.
res <- dpla_items(subject = "churches", type = "image", page_size = 500)
df <- res$data
dates <- unlist(df$date, use.names = FALSE)
# remove 2nd part of a duration separted by " - ", just use first date
dates <- gsub("\\s-\\s.+", "", dates)
# remove 2nd part of a duration separted by "/", just use first date
dates <- gsub("/.+", "", dates)
# remove 2nd part of a duration separted by "-", just use first date
dates <- gsub("-[0-9]{4}", "", dates)
# remove any text, can't parse it
dates <- gsub("[[:alpha:]]+", "", dates)
# trim leading and trailing white space
dates <- gsub("^\\s+|\\s+$", "", dates)
# parse dates
df$date_corr <- parse_date_time(dates, c("Y", "ymd", "ym", "%Y-%m-%d%H:%M:%S%z"))
Make year column
df$year <- year(df$date_corr)
Summarize by year
df_dt <- as.data.table(df)
df_dt <- df_dt[order(year)]
df_sum <- df_dt[, list(count = length(id)), by = year]
df_sum <- as.data.frame(na.omit(df_sum))
library("ggplot2")
ggplot(df_sum, aes(x = year, y = count)) +
geom_bar(stat = "identity") +
theme_gray(base_size = 18)
Zooming in on the majority of the data
ggplot(subset(df_sum, year > 1800), aes(x = year, y = count)) +
geom_bar(stat = "identity") +
theme_gray(base_size = 18)
Looks like there's a big spike in 1930
Let's have a look at a few of the titles
sort(unique(subset(df, year == 1930)$title))[1:10]
#> [1] "Associated Reformed Presbyterian Church, Chester, S. C"
#> [2] "Bethlehem Lutheran Church, U. A. C., 3705 South Anthony Boulevard, Fort Wayne, Indiana"
#> [3] "Blandford Church, Petersburg, Va., interior of Blandford Church"
#> [4] "Blessed Sacrament Church, Bolton Landing, N. Y"
#> [5] "Blessed Sacrament Church, Holyoke, Mass"
#> [6] "Broad Street Methodist Episcopal Church, south, Richmond, VA"
#> [7] "Bryan Memorial Church, Miami, Florida"
#> [8] "Cathedral of San Francisco de Assisi, Santa Fe, New Mexico"
#> [9] "Cathedral of St. John--The Baptist, Charleston, S. C"
#> [10] "Cathedral of the Holy Spirit, Bismarck, N. Dak"