Add code and slides from web APIs webinar

40-web-apis-with-httr/github.R

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+library(httr)
+
+# OAuth 2 example, lifted from https://github.com/hadley/httr/blob/master/demo/oauth2-github.r
+
+# 1. Find OAuth settings for github:
+#    http://developer.github.com/v3/oauth/
+oauth_endpoints("github")
+
+# 2. To make your own application, register at at
+#    https://github.com/settings/applications. Use any URL for the homepage URL
+#    (http://github.com is fine) and  http://localhost:1410 as the callback url
+#
+#    IRL, you'd want to set the key and secret as environment variables to keep them out of the code.
+ghapp <- oauth_app("github",
+                   key = "56b637a5baffac62cad9",
+                   secret = "8e107541ae1791259e9987d544ca568633da2ebf"
+)
+# 3. Get OAuth credentials
+github_token <- oauth2.0_token(oauth_endpoints("github"), ghapp, cache = TRUE)
+
+# 4. Use API
+gtoken <- config(token = github_token)
+req <- GET("https://api.github.com/rate_limit", gtoken)
+stop_for_status(req)
+rate_limit <- content(req)
+rate_limit$resources$core$limit
+
+# See API documentation for all resources, examples

40-web-apis-with-httr/resources/styles.css

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+.gdbar img {
+  width: 250px !important;
+  height: 88px !important;
+  margin: 8px 8px;
+}
+
+.gdbar {
+  width: 300px !important;
+  height: 100px !important;
+}
+
+slides > slide:not(.nobackground):before {
+  width: 100px;
+  height: 35px;
+  background-size: 100px 35px;
+}

40-web-apis-with-httr/swapi.R

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+library(httr)
+library(jsonlite)
+library(magrittr)
+
+# Goal: Get the data for the planet Alderaan
+# verb (method) = GET
+# URL (endpoint) = http://swapi.co/api/planets/
+# parameter = search
+
+alderaan <- GET("http://swapi.co/api/planets/?search=alderaan")
+# Same call in a different format
+alderaan <- GET("http://swapi.co/api/planets/", query = list(search = "alderaan"))
+
+names(alderaan)
+alderaan$status_code
+alderaan$headers$`content-type`
+
+# Get the content of the response
+text_content <- content(alderaan, "text", encoding = "UTF-8")
+text_content
+
+# Parse with httr
+parsed_content <- content(alderaan, "parsed")
+names(parsed_content)
+parsed_content$count
+str(parsed_content$results)
+parsed_content$results[[1]]$name
+parsed_content$results[[1]]$terrain
+
+# Parse with jsonlite
+json_content <- text_content %>% fromJSON
+json_content
+planetary_data <- json_content$results
+names(planetary_data)
+planetary_data$name
+planetary_data$terrain
+
+# -------------------------------
+
+# Helper function
+json_parse <- function(req) {
+  text <- content(req, "text", encoding = "UTF-8")
+  if (identical(text, "")) warning("No output to parse.")
+  fromJSON(text)
+}
+
+# List results
+planets <- GET("http://swapi.co/api/planets") %>% stop_for_status()
+json_planets <- json_parse(planets)
+
+# The response includes metadata as well as results
+names(json_planets)
+json_planets$count
+length(json_planets$results$name)
+json_planets$`next`
+
+swapi_planets <- json_planets$results
+swapi_planets$name
+
+# Get the next page of results based on the content of the `next` field
+next_page <- GET(json_planets$`next`) %>% stop_for_status()
+
+# Use a function to parse the results
+parsed_next_page <- json_parse(next_page)
+parsed_next_page$results$name
+
+# If the API results come back paged like this, you can write a loop to follow the next URL 
+# until the there are no more pages, and rbind all the data into a single dataframe.
+
+# Grab data on all of the Star Wars planets
+planets <- GET("http://swapi.co/api/planets") %>% 
+  stop_for_status() %>% 
+  json_parse
+swapi_planets <- planets$results
+
+next_page <- planets$`next`
+while (!is.null(next_page)) {
+  more_planets <- GET(next_page) %>% 
+    stop_for_status() %>% 
+    json_parse
+  swapi_planets <- rbind(swapi_planets, more_planets$results)
+  next_page <- more_planets$`next`
+}
+
+length(swapi_planets$name)
+swapi_planets$name
+
+# In real life, you'd also want to handle any errors, headers, proxy, rate limits, etc. as needed.
+help(package = httr)
+
+# Someone wrote a package for swapi:  https://github.com/Ironholds/rwars

40-web-apis-with-httr/twitter.R

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+library(httr)
+
+# OAuth 1 example, mostly lifted from https://github.com/hadley/httr/blob/master/demo/oauth1-twitter.r
+
+# 1. Find OAuth settings for twitter: https://dev.twitter.com/docs/auth/oauth
+oauth_endpoints("twitter")
+# use oauth_endpoint() if you are accessing an API not covered in the convenience method oauth_endpoints
+
+# 2. Register an application at https://apps.twitter.com/
+#    Make sure to set callback url to "http://127.0.0.1:1410/"
+#
+#    IRL, you'd want to set the key and secret as environment variables to keep them out of the code.
+myapp <- oauth_app("twitter",
+                   key = "TYrWFPkFAkn4G5BbkWINYw",
+                   secret = "qjOkmKYU9kWfUFWmekJuu5tztE9aEfLbt26WlhZL8"
+)
+
+# 3. Get OAuth credentials
+twitter_token <- oauth1.0_token(oauth_endpoints("twitter"), myapp, cache = TRUE)
+
+# 4. Use API
+req <- GET("https://api.twitter.com/1.1/statuses/user_timeline.json?screen_name=rstudiotips&count=10",
+           config(token = twitter_token))
+stop_for_status(req)
+rstudio_tips <- content(req)
+rstudio_tips[[1]]$text
+
+# See API documentation for all resources, examples