14.5.3 Data Visualization

Unlock the Power of Data Visualization in Clojure

Data visualization is crucial in making complex data comprehensible and interpreting analytical insights. In this section, we’ll explore how Clojure, when paired with tools like Incanter, Oz, and Hanami, enables powerful data visualizations with concise expressions.

Incanter Charts

Incanter is a popular Clojure library for statistical data analysis that comes with robust charting capabilities. We’ll highlight how to utilize Incanter’s functions to create various chart types, including bar charts, scatter plots, and histograms.

Example: Creating a Simple Histogram

Below is an example of how to create a histogram with Incanter:

(use '(incanter core stats charts))

(let [data (sample-normal 1000)]
  (view (histogram data :nbins 20 :title "Normal Distribution")))

Vega/Vega-Lite with Oz

Vega and Vega-Lite are powerful declarative visualization grammar tools. Using the oz library, Clojure can make use of these to generate highly interactive and aesthetic visualizations.

Example: Vega-Lite Specification with Oz

Here’s how to create a Vega-Lite bar chart using oz:

(require '[oz.core :as oz])

(def sample-data
  {:data {:values [{:category "A" :amount 28}
                   {:category "B" :amount 55}
                   {:category "C" :amount 43}]}])

(def bar-chart {:mark "bar",
                :encoding {:x {:field "category", :type "ordinal"},
                           :y {:field "amount", :type "quantitative"}}})

(oz/view! (merge sample-data bar-chart))

Hanami: Declarative Data Visualization

Hanami is another library in the Clojure ecosystem designed to leverage the flexibility of Vega-Lite for easy, declarative visualization creation.

Example: Constructing a Line Chart with Hanami

Here is a concise way to construct a line chart using Hanami’s syntax:

(require '[hanami.core :as hanami])

(def line-spec {:data {:values (for [x (range 0 10)]
                                  {:x x :y (+ (* x x) (rand 10))})}
                :mark "line"
                :encoding {:x {:field "x" :type "quantitative"}
                           :y {:field "y" :type "quantitative"}}})

(hanami/view! line-spec)

Generate Common Chart Types

Each library offers ways to represent your data through different visualization types like line charts, area charts, pie charts, and more. Tailor your visualization technique to the narrative of the data.

Summary and Best Practices

• Understand the strengths of each tool and leverage them according to your data visualization requirements.
• Ensure interactive features complement the user experience without overwhelming the analysis narrative.
• Strive to maintain a balance between aesthetics and clarity in your visualization creations.

This guide has introduced you to several tools that facilitate data visualization in Clojure, enhancing your applications’ data presentation capabilities. Continue experimenting with these libraries to augment your applications with insightful and quality visualizations.