Introduction

We handle the data so you can focus on the science

Finding data is one thing. Getting it ready for analysis is another. Acquiring, cleaning, standardizing and importing publicly available data is time consuming because many datasets lack machine readable metadata and do not conform to established data structures and formats.

The Data Retriever automates the first steps in the data analysis pipeline by downloading, cleaning, and standardizing datasets, and importing them into relational databases, flat files, or programming languages. The automation of this process reduces the time for a user to get most large datasets up and running by hours, and in some cases days.

What data tasks does the Retriever handle

The Data Retriever handles a number of common tasks including:
  1. Creating the underlying database structures, including automatically determining the data types
  2. Downloading the data
  3. Transforming data into appropriately normalized forms for database management systems (e.g., “wide” data into “long” data and splitting tables into proper sub-tables to reduce duplication)
  4. Converting heterogeneous null values (e.g., 999.0, -999, NaN) into standard null values
  5. Combining multiple data files into single tables; and 6) placing all related tables in a single database or schema.

A couple of examples on the more complicated end include the Breeding Bird Survey of North America (breed-bird-survey) and the Alwyn Gentry Tree Transect data(gentry-forest-transects):

  • Breeding bird survey data consists of multiple tables. The main table is divided into one file per region in 70 individual compressed files. Supplemental tables required to work with the data are posted in a variety of locations and formats. The Data Retriever automates: downloading all data files, extracting data from region-specific raw data files into single tables, correcting typographic errors, replacing non-standard null values, and adding a Species table that links numeric identifiers to actual species names.
  • The Gentry forest transects data is stored in over 200 Excel spreadsheets, each representing an individual study site, and compressed in a zip archive. Each spreadsheet contains counts of individuals found at a given site and all stems measured from that individual; each stem measurement is placed in a separate column, resulting in variable numbers of columns across rows, a format that is difficult to work with in both database and analysis software. There is no information on the site in the data files themselves, it is only present in the names of the files. The Retriever downloads the archive, extracts the files, and splits the data they contain into four tables: Sites, Species, Stems, and Counts, keeping track of which file each row of count data originated from in the Counts table and placing a single stem on each row in the Stems table.

Adapted from Morris & White 2013.

Installing (binaries)

Precompiled binaries of the most recent release are available for Windows, OS X, and Ubuntu/Debian at the project website.

Installing From Source

Required packages

To install the Data Retriever from source, you’ll need Python 2.6+ or Python 3.3+ with the following packages installed:

  • xlrd

The following packages are optional

  • PyMySQL (for MySQL)
  • sqlite3 (for SQLite, v3.8 or higher required)
  • psycopg2 (for PostgreSQL)
  • pypyodbc (for MS Access)

Steps to install from source

  1. Clone the repository
  2. From the directory containing setup.py, run the following command: python setup.py install or use pip pip install . --upgrade to install and pip uninstall retriever to uninstall the retriever
  3. After installing, type retriever from a command prompt to see the available options of the Data Retriever. Use retriever --version to confirm the version installed on your system.

Using the Data Retriever Commands

After installing, run retriever update to download all of the available dataset scripts. Run retriever ls to see the available datasets

To see the full list of command line options and datasets run retriever --help. The output will look like this:

usage: retriever [-h] [-v] [-q]
                 {download,install,defaults,update,new,new_json,edit_json,delete_json,ls,citation,reset,help}
                 ...

positional arguments:
  {download,install,defaults,update,new,new_json,edit_json,delete_json,ls,citation,reset,help}
                        sub-command help
    download            download raw data files for a dataset
    install             download and install dataset
    defaults            displays default options
    update              download updated versions of scripts
    new                 create a new sample retriever script
    new_json            CLI to create retriever datapackage.json script
    edit_json           CLI to edit retriever datapackage.json script
    delete_json         CLI to remove retriever datapackage.json script
    ls                  display a list all available dataset scripts
    citation            view citation
    reset               reset retriever: removes configation settings,
                        scripts, and cached data
    help

optional arguments:
  -h, --help            show this help message and exit
  -v, --version         show program's version number and exit
  -q, --quiet           suppress command-line output

To install datasets, use the install command.

Examples

Using install

The install command downloads the datasets and installs them in the desired engine.

$ retriever install -h (gives install options)

usage: retriever install [-h] [--compile] [--debug]
                         {mysql,postgres,sqlite,msaccess,csv,json,xml} ...
positional arguments:
  {mysql,postgres,sqlite,msaccess,csv,json,xml}
                        engine-specific help
    mysql               MySQL
    postgres            PostgreSQL
    sqlite              SQLite
    msaccess            Microsoft Access
    csv                 CSV
    json                JSON
    xml                 XML
optional arguments:
  -h, --help            show this help message and exit
  --compile             force re-compile of script before downloading
  --debug               run in debug mode

Examples using install

These examples use Breeding Bird Survey data (breed-bird-survey). The retriever has support for various databases and flat file formats (mysql, postgres, sqlite, msaccess, csv, json, xml). All the engines have a variety of options or flags. Run `retriever defaults to see the defaults. For example, the default options for mysql and postgres engines are given below.

retriever defaults

Default options for engine  MySQL
user   root
password
host   localhost
port   3306
database_name   {db}
table_name   {db}.{table}

Default options for engine  PostgreSQL
user   postgres
password
host   localhost
port   5432
database   postgres
database_name   {db}
table_name   {db}.{table}

Help information for a particular engine can be obtained by running retriever install [engine name] [-h] [–help], for example, retriever install mysql -h. Both mysql and postgres require the database user name --user [USER], -u [USER] and password --password [PASSWORD], -p [PASSWORD]. MySQL and PostgreSQL database management systems support the use of configuration files. The configuration files provide a mechanism to support using the engines without providing authentication directly. To set up the configuration files please refer to the respective database management systems documentation.

Install data into Mysql:

retriever install mysql –-user myusername –-password ***** –-host localhost –-port 8888 –-database_name testdbase breed-bird-survey
retriever install mysql –-user myusername breed-bird-survey (using attributes in the client authentication configuration file)

Install data into postgres:

retriever install postgres –-user myusername –-password ***** –-host localhost –-port 5432 –-database_name testdbase breed-bird-survey
retriever install postgres breed-bird-survey (using attributes in the client authentication configuration file)

Install data into sqlite:

retriever install sqlite breed-bird-survey -f mydatabase.db (will use mydatabase.db)
retriever install sqlite breed-bird-survey (will use or create default sqlite.db in working directory)

Install data into csv:

retriever install csv breed-bird-survey --table_name  "BBS_{table}.csv"
retriever install csv breed-bird-survey

Using download

The download command downloads the raw data files exactly as they occur at the source without any clean up or modification. By default the files will be stored in the working directory.

--path can be used to specify a location other than the working directory to download the files to. E.g., --path ./data

--subdir can be used to maintain any subdirectory structure that is present in the files being downloaded.

retriever download -h (gives you help options)
retriever download breed-bird-survey (download raw data files to the working directory)
retriever download breed-bird-survey –path  C:\Users\Documents (download raw data files to path)

Using citation

The citation command show the citation for the retriever and for the scripts.

retriever citation (citation of the Data retriever)
retriever citation breed-bird-survey (citation of Breed bird survey data)

To create new, edit, delete scripts please read the documentation on scripts

Acknowledgments

Development of this software was funded by the Gordon and Betty Moore Foundation’s Data-Driven Discovery Initiative through Grant GBMF4563 to Ethan White and the National Science Foundation as part of a CAREER award to Ethan White.