Accessing the Strava API with R

Strava is an online platform for storing and sharing fitness data. Strava provides an API for accessing such data at the activity (e.g., run or cycle) level. This post explains how I authenticate with, and extract data from, the Strava API using R. I implement my method in the R package stravadata.

Setup and authentication

Strava uses OAuth 2.0 to authorise access to the API data. The first step to becoming authorised is to register for access on Strava’s API settings page. I put “localhost” in the “Authorization Callback Domain” field. Upon completing the registration form, the page provides two important values: an integer client ID and an alpha-numeric client secret. I store these values in credentials.yaml, which I structure as

client_id: xxxxxxxxx
secret: xxxxxxxxx

and import into R using the read_yaml function from the yaml package.

Next, I create an OAuth application for interacting with the API and an endpoint through which to send authentication requests. I use the oauth_app and oauth_endpoint functions from httr:

library(httr)

app <- oauth_app("strava", credentials$client_id, credentials$secret)
endpoint <- oauth_endpoint(
  request = NULL,
  authorize = "https://www.strava.com/oauth/authorize",
  access = "https://www.strava.com/oauth/token"
)

Finally, I create an OAuth access token to send the authentication request to my Strava account. This token encapsulates the application and endpoint defined above. Running¹

token <- oauth2.0_token(endpoint, app, as_header = FALSE,
                        scope = "activity:read_all")

opens a browser window at a web page for accepting the authentication request. Doing so redirects me to the callback domain (“localhost”) and prints a confirmation message:

Authentication complete. Please close this page and return to R.

Extracting the data

After authenticating with Strava, I use HTTP requests to extract activity data from the API. The API returns multiple pages of data, each containing up to 200 activities. I use a while loop to iterate over pages, using the fromJSON function from jsonlite to parse the extracted data:

library(jsonlite)

df_list <- list()
i <- 1
done <- FALSE
while (!done) {
  req <- GET(
    url = "https://www.strava.com/api/v3/athlete/activities",
    config = token,
    query = list(per_page = 200, page = i)
  )
  df_list[[i]] <- fromJSON(content(req, as = "text"), flatten = TRUE)
  if (length(content(req)) < 200) {
    done <- TRUE
  } else {
    i <- i + 1
  }
}

Finally, I use the rbind_pages function from jsonlite to collate the activity data into a single data frame:

df <- rbind_pages(df_list)