Incanter comes with a set of default datasets that are useful for exploring Incanter's functions. I haven't made use of them in this book, since there is so much data available in other places, but they're a great way to get a feel of what you can do with Incanter. Some of these datasets—for instance, the Iris dataset—are widely used to teach and test statistical algorithms. It contains the species and petal and sepal dimensions for 50 irises. This is the dataset that we'll access today.
In this recipe, we'll load a dataset and see what it contains.
We'll need to include Incanter in our Leiningen project.clj file:
(defproject inc-dsets "0.1.0"
:dependencies [[org.clojure/clojure "1.6.0"]
[incanter "1.5.5"]])We'll also need to include the right Incanter namespaces into our script or REPL:
(use '(incanter core datasets))
Once the namespaces are available, we can access the datasets easily:
user=> (def iris (get-dataset :iris))
#'user/iris
user=> (col-names iris)
[:Sepal.Length :Sepal.Width :Petal.Length :Petal.Width :Species]
user=> (nrow iris)
150
user=> (set ($ :Species iris))
#{"versicolor" "virginica" "setosa"}We use the get-dataset function to access the built-in datasets. In this case, we're loading the Fisher's Iris dataset, sometimes called Anderson's dataset. This is a multivariate dataset for discriminant analysis. It gives petal and sepal measurements for 150 different Irises of three different species.
Incanter's sample datasets cover a wide variety of topics—from U.S. arrests to plant growth and ultrasonic calibration. They can be used to test different algorithms and analyses and to work with different types of data.
By the way, the names of functions should be familiar to you if you've previously used R. Incanter often uses the names of R's functions instead of using the Clojure names for the same functions. For example, the preceding code sample used nrow instead of count.
Incanter's API documentation for get-dataset (http://liebke.github.com/incanter/datasets-api.html#incanter.datasets/get-dataset) lists more sample datasets, and you can refer to it for the latest information about the data that Incanter bundles.