Astrology has been practiced in various forms for thousands of years and is still very popular today as a sort of cultural and psychological phenomenon. For this project I wanted to explore the checkout activity over time of items related to astrology at the Seattle Public Library. My initial idea for the visualization was inspired by the circular form of a birth chart.

SELECT
itemnumber,
bibNumber,
DATE(cout) AS coutDate,
DATE(cin) AS cinDate,
TIME(cout) AS coutTime,
TIME(cin) AS cinTime,
title
FROM
spl_2016.inraw
WHERE
title LIKE '%astrology%'
ORDER BY itemNumber;

SELECT
YEAR(i.cout) AS year,
COUNT(*) AS count
FROM
(SELECT
bibNumber, cout, itemType, title
FROM
spl_2016.outraw
WHERE
title LIKE '%astrology%') AS i
GROUP BY YEAR(i.cout)
ORDER BY year;

I wanted to have a circular form with a line representing each checkout so that it would look somewhat like a birth chart when viewed from a certain angle.



This is my initial sketch. I wanted to represent time as a spiral and connect checkout and check-in dates with a line.

This is what my visualization initially looked like. Each checkout/check-in is represented by a Bezier curve. Each item (identified by bibNumber) has a different color determined by when it first appears in the result from the query, which sorts the data by itemNumber. So the acquisition date of the item is shown by the hue of the color.



I noticed that the popularity of checkouts varied quite a bit throughout the years so to make the overall shape of the spiral more interesting, I performed a polynomial regression of the data representing checkouts per year (second query). I used this website to generate this polynomial of degree 7. I then used this polynomial to determine the radius of the spiral at any given point in time so that the size of the spiral approximates the popularity checkouts during a period of time.

This is the final result of my visualization with all titles selected. In addition to the using polynomial regression, I also changed the shape of the Bezier curves.



This is a front view of the visualization.



Here, only some titles are selected.

All work is developed within Processing
Source Code + Data