R script to read Air Quality Egg NO2 data from Cosm and plot it

gistfile1.r

install.packages('RCurl')
install.packages("ggplot2")
library(ggplot2)
library(RCurl)

# grab an api key from cosm and put it here
api_key = 'YOUR_API_KEY'

# your feed id
feed_id = '106267'

csv_data = ""
start_date = as.POSIXct("2013/05/07","GMT")
end_date = as.POSIXct("2013/05/08","GMT")

while (start_date < end_date) {
  start_date_as_str = format(start_date, format="%Y-%m-%dT%H:%M:00Z")
  next_date = start_date + (3 * 60 * 60)
  next_date_as_str = format(next_date, format="%Y-%m-%dT%H:%M:00Z")
  cosm_url = paste("http://api.cosm.com/v2/feeds/", feed_id, "/datastreams/NO2_00-04-a3-37-cc-cb_0.csv?start=", start_date_as_str, "&end=", next_date_as_str,"&interval=0", sep="")    
  csv_data_for_period = getURL(cosm_url, httpheader = c('X-ApiKey' = api_key) )
  csv_data = paste(csv_data, csv_data_for_period, "\n")
  start_date = next_date
}

data = read.table(textConnection(csv_data), sep = ",", col.names=c("at", "value"))
data$timestamp <- strptime(data$at, "%FT%T", tz = "UTC")

# strip out outliers
data = data[which(data$value < 1000),]

#summary(data)

ggplot(data, aes(timestamp,value)) + geom_point() + geom_smooth() + xlab("Time") + ylab("NO2 PPB")