fetchGoogle: Fetch data from a web service
In ProjectMOSAIC/fetch: Tools for Fetching Data

Description Usage Arguments Details Note Author(s) Examples

Read a data set generated from a web service such as Google Docs.

1	fetchGoogle(URL, key = NULL)

`URL`	the URL to retrieve a CSV file from the service
`key`	for convenience, just the "key" part of the Google link

Web services such as Google Docs allow you to store spreadsheets "in the cloud". By setting permissions in the service, you can arrange to make the data set public, so that anyone with an appropriate URL can access the data. Reading such data into R can be done simply if the service supports exporting the data in a CSV format via URL link. For instance, Google Spreadsheets can be set up to publish a spreadsheet via a URL. Unfortunately, the read.csv() function, although able to read URLs pointing to a file, cannot handle the protocol needed to talk to services such as Google Docs. fetchGoogle() allows you to do this. fetchGoogle() derives its functionality from the RCurl package, which must be installed for the function to work. RCurl will be loaded automatically if it is installed. Generating the URL from the web service will, of course, depend on how that service is set up. For Google Spreadsheets, you, the owner of a spreadsheet, can (1) open the spreadsheet in a browser (2) select the File/Publish to the Web menu item (3) in the resulting dialog box, press "Start publishing" (4) under "Get a link to the published data", select CSV format (5) copy the https://docs.google.com/spreadsheet/pub?... link and post it where your users can get to it.

The URL must instruct the service to generate a CSV file. The URLs from Google Docs are very long and contain random-looking sequences. You may want to post the URL on a web page whence it can be cut and paste as part of the command. The key= argument is provided as a convenience so that a shorter character string can be used to refer to a Google document. Use URL rather than key if you are using a non-Google service or if the Google interface changes. fetchData() expects the spreadsheet to be in a straightforward rectangular spreadsheet format.

Daniel Kaplan (kaplan@macalester.edu)