Download FitBit step counts using API.

FitBit.R

library(httr)
library(rjson)

key <- '<edited>'
secret <- '<edited>'
tokenURL <- 'http://api.fitbit.com/oauth/request_token'
accessTokenURL <- 'http://api.fitbit.com/oauth/access_token'
authorizeURL <- 'http://www.fitbit.com/oauth/authorize'

fbr <- oauth_app('MyHome', key, secret)
fitbit <- oauth_endpoint(tokenURL, authorizeURL, accessTokenURL)

token <- oauth1.0_token(fitbit, fbr)
sig <- sign_oauth1.0(fbr,
                     token=token$oauth_token,
                     token_secret=token$oauth_token_secret
)

data <- data.frame(seq(from = as.Date("2013-05-24"), to = as.Date("2013-08-31"), by = 1))
data$steps <- 0
colnames(data) <- c('date', 'steps')

for (index in 1:nrow(data)) {
  URL <- paste('http://api.fitbit.com/1/user/-/activities/date/', data[index, 1], '.json', sep = '')
  rawData <- GET(URL, sig)[[6]]
  charData <- rawToChar(rawData, multiple = FALSE)
  parseData <- fromJSON(charData, method = 'C')
  data[index, 2] <- parseData$summary$steps
}