Julia API for accessing Socrata open data sets
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README.md

Socrata.jl

Socrata.jl is a Julia wrapper for accessing the Socrata Open Data API (http://dev.socrata.com) and importing data into a DataFrame. Socrata is an open data platform used by many local and State governments as well as by the Federal Government.

Here are just a few examples of Socrata datasets/repositories:

More Open Data Resources can be found here.

Installation

Pkg.clone("https://github.com/dreww2/Socrata.jl.git")

Basic Usage

The Socrata API consists of a single function, socrata, which at a minimum takes a Socrata url and returns a DataFrame:

julia> using Socrata

julia> df = socrata("http://soda.demo.socrata.com/resource/4334-bgaj")
100x9 DataFrame
|-------|--------------------|------------|---------|
| Col # | Name               | Eltype     | Missing |
| 1     | Source             | UTF8String | 0       |
| 2     | Earthquake_ID      | UTF8String | 0       |
| 3     | Version            | UTF8String | 0       |
| 4     | Datetime           | UTF8String | 0       |
| 5     | Magnitude          | Float64    | 0       |
| 6     | Depth              | Float64    | 0       |
| 7     | Number_of_Stations | Int64      | 0       |
| 8     | Region             | UTF8String | 0       |
| 9     | Location           | UTF8String | 0       |

The url may be a Socrata API Endpoint or may be the URL from the address bar (in which case Socrata.jl will automatically attempt to parse the string into a usable format). For example, the following are all valid urls for the same dataset:

Optional Arguments

Basic Arguments

There are several optional keyword string arguments:

  • app_token is your Socrata application token which allows for more API requests per unit of time
  • limit is equal to the number of rows in the dataset you would like to retrieve. Default is equal to 100, max is equal to 1,000 (Socrata's limit). If you want to download a large dataset, set fulldataset=true (see below).
  • offset indicates the first row from which to start pulling data.
  • fulldataset ignores all query parameters including limit, offset, and any of the Socrata Query Language (SoQL) arguments and downloads the entire dataset.
  • usefieldids is not yet implemented, but will substitute the default human-readable column headers with API field IDs.

Socrata Query Language (SoQL) Arguments

Socrata.jl supports SoQL queries using the following arguments:

  • select
  • where
  • order
  • group
  • q
  • limit and offset as described above.

Note that any references to columns inside these arguments must reference the dataset's API Field ID, which can be found on any Socrata dataset page under Export => SODA API => Column IDs.

Examples

using Socrata

url = "http://soda.demo.socrata.com/resource/4334-bgaj"
token = "your_app_token_goes_here"

A basic query, getting the first 5 rows:

df = socrata(url, app_token=token, limit="5")

Get rows 5-10 of the data:

df = socrata(url, app_token=token, limit="5", offset="5")

Get only the first 10 rows and the Source, Earthquake_ID, Magnitude, and Region columns:

df = socrata(url, app_token=token, limit="10", select="source, earthquake_id, magnitude, region")

You can add multiple conditions within a single argument. For example, get only rows where magnitude is greater than 5.5 and depth is less than 30:

df = socrata(url, app_token=token, where="magnitude > 5.5 AND depth < 30")

Search for Hawaii in the dataset where Magnitude > 2 and only select certain columns:

df = socrata(url, app_token=token, q="hawaii", where="magnitude > 2", select="datetime, magnitude, region, location")

TODO

  • Add support for automatically getting API Field IDs
  • Implement better app_token system
  • Add support for JSON and XML