Visualisation 2012 - 2013 Lecture 3 Brian Mac Namee Dublin institute of Technology Applied...

Visualisation2012 - 2013

Lecture 3

Brian Mac NameeDublin institute of Technology

Applied Intelligence Research Centre

Visualising Trends

Origins

This course is based heavily on a course developed by Colman McMahon (www.colmanmcmahon.com)

Material from multiple other online and published sources is also used and when this is the case full citations will be given

22011/12

http://www.colmanmcmahon.com/

Visualization of the Week

www.pinterest.com/brianmacnamee/great-visualisation-examples/

http://pinterest.com/brianmacnamee/great-visualisation-examples/

(Un)Visualization of the Week

www.pinterest.com/brianmacnamee/terrible-visualisation-examples/

http://www.pinterest.com/brianmacnamee/terrible-visualisation-examples/

Agenda

Visualising patterns over time

Discrete points in time

Continuous points in time

Handling multiple dimensions over time

52011/12

What To Look For

The most common thing you look for in time series, or temporal, data is trends

- Is something increasing or decreasing?

- Are there seasonal cycles?

To find these patterns, you have to look beyond individual data points to get the whole picture

2011/12 7

Visualising Patterns Over Time

Visualising patterns over time

- Discrete points in time

• Bar Graph

• Scatter Plot

- Continuous points in time

• Line Chart

• Step Chart

- Handling multiple dimensions over time

• Stacked Bar Chart

• Area Chart

• Stream Graph

• Small Multiples

• Animation2011/12 8

Discrete Points In Time

Often we have datasets that contain single measurements for a reasonably small number of discrete points in time

- Profit per year

- Rainfall per month

In these cases a simple bar graph is often appropriate

Simple Bar Graph

“Visualize This”, N. Tau, Wiley, 2011

http://shop.oreilly.com/product/0636920022060.do


Simple Bar Graph




Simple Bar Graph

http://www.mornpen.vic.gov.au/page/imageThumbnail.asp?C_Id=820

http://www.mornpen.vic.gov.au/page/imageThumbnail.asp?C_Id=820

Continuous Points In Time

Often we have datasets that contain single measurements for a number of continuous points of time

- Stock prices over time

- Internet traffic over time

In these cases a line charts are more appropriate

Simple Scatter Plot

2011/12 14




Simple Scatter Plot




Simple Line Chart

Simply adding a line to a scatter plot can help greater emphasise a trend over time




Simple Line Chart




Simple Line Chart




Step Chart

Basic line charts interpolate the change in measurement from one point in time to another

Often this is not appropriate and in these cases step charts are more appropriate




Step Chart

2011/12 20




Step Chart




Fitting A Line

In some cases adding a line to a scatter plot can mask the trend over time rather than help illustrate it

In this cases it can be more appropriate to fit a line or curve to a dataset so as to highlight a trend in time

ACHTUNG: Be careful when fitting lines, it is possible to illustrate trends that don’t really exist

Fitting A Line




Smoothing & Estimation

2011/12 24




Multiple Dimensions In Time

Often we have datasets that contain multiple measurement for each point in time which gives us multiple dimensions

This makes visualization more challenging as we need to use newer and different encodings

There are a number of approaches we can take

Stacked Bar Chart




Stacked Bar Chart

Charting U.S. Gun Manufacturing, Matt Stiles, The Daily Viz, 2012http://thedailyviz.com/2012/08/07/charting-u-s-gun-manufacturing/

http://thedailyviz.com/2012/08/07/charting-u-s-gun-manufacturing/

Stacked Bar Chart

Interpreting multiple time series in a stacked bar chart can be really difficult, especially when we need to interpret the trend within the higher categories

Only really appropriate when the real trend we want to illustrate is the overall total bar height trend and the individual categories are secondary

Multiple Line Series

http://hci.stanford.edu/jheer/files/zoo/ex/time/index-chart.html

http://hci.stanford.edu/jheer/files/zoo/ex/time/index-chart.html

Multiple Line Series

Displaying time-series data: Stacked bars, area charts or lines…you decide!, VizWiz, 2012

http://vizwiz.blogspot.ie/2012/08/displaying-time-series-data-stacked.html

U.S. Gun Manufacturing By Type


Stacked Area Chart




Stacked Area Chart

U.S. Gun Manufacturing By Type




Stacked Area Chart

Stacked area charts unfortunately suffer from many of the same problems as stacked bar charts

It can be very hard to interpret the trends of each category as they are stacked on top of each other

Stacked Area Chart



What does the shotgun trend look like?


Stacked Area Chart




Stream Graph

The Stream Graph is an attempt to overcome the difficulties associated with stacked bar charts and stacked area charts

Stream Graph

ThemeRiver: Visualizing Theme Changes over Time, Susan Havre , Beth Hetzler , Lucy Nowell, Proc. IEEE Symposium on Information Visualization, 2000.

http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.135.4974


Stream Graph

ThemeRiver: Visualizing Theme Changes over Time, Susan Havre , Beth Hetzler , Lucy Nowell, Proc. IEEE Symposium on Information Visualization, 2000.



Stream Graph

Stacked Graphs – Geometry & Aesthetics, Lee Byron & Martin Wattenberg, 2008.http://www.leebyron.com/what/lastfm/

http://www.leebyron.com/what/lastfm/

Stream Graph



Stream Graph



Stream Graph

http://hci.stanford.edu/jheer/files/zoo/ex/time/stack.html

http://hci.stanford.edu/jheer/files/zoo/ex/time/stack.html

The Ebb and Flow of Movies: Box Office Receipts 1986 — 2008, New York Timeshttp://www.nytimes.com/interactive/2008/02/23/movies/20080223_REVENUE_GRAPHIC.html

Stream Graph

http://www.nytimes.com/interactive/2008/02/23/movies/20080223_REVENUE_GRAPHIC.html

http://www.nytimes.com/interactive/2008/02/23/movies/20080223_REVENUE_GRAPHIC.html

Small Multiples

One solution to illustrating time is to use small multiples to show multiple snapshots of the data at different points in time

Small Multiples

http://hci.stanford.edu/jheer/files/zoo/ex/time/multiples.html

http://hci.stanford.edu/jheer/files/zoo/ex/time/multiples.html

Small Multiples

Small Multiples

Tres Epistolae de Maculis Solaribus Scriptae ad Marcum Welserum, Christoph Scheiner, 1612

http://galileo.rice.edu/sci/observations/sunspots.html

http://galileo.rice.edu/sci/observations/sunspots.html

Animation

Animation is obviously a great way to illustrate changes over time

We will look at this more later in the course

Animation

www.ted.com/talks/hans_rosling_shows_the_best_stats_you_ve_ever_seen.html

http://www.ted.com/talks/hans_rosling_shows_the_best_stats_you_ve_ever_seen.html

Animation

Galileo's Sunspot Drawingshttp://galileo.rice.edu/sci/observations/ssm_slow.mpg

Gallileo made flip books of sunspot images to show how they moved over time

http://galileo.rice.edu/sci/observations/ssm_slow.mpg

Conclusions

Visualising across time is a key methodology

There are a number of approaches that are common and useful

We will come back to animation

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