COMP3021 Data Fundamentals of Visualization Lecture 2 PDF

COMP3021 COMP3021 Data Fundamentals of Visualization Information Visualization Lecture 2: The Value of Visualization Ke Zhou & Kai Xu School of Computer Science...

COMP3021 COMP3021 Data Fundamentals of Visualization Information Visualization Lecture 2: The Value of Visualization Ke Zhou & Kai Xu School of Computer Science Dr. Ke Zhou (http://www.cs.nott.ac.uk/~pszkz/) COMP3021 Overview What are the Key Values of IV? – Record – Communicate – Reason What is the Process of IV? Dr. Ke Zhou (http://www.cs.nott.ac.uk/~pszkz/) COMP3021 What are the Key Values of IV? Dr. Ke Zhou (http://www.cs.nott.ac.uk/~pszkz/) G53FIV Why Create Visualization? Dr. Ke Zhou (http://www.cs.nott.ac.uk/~pszkz/) G53FIV Why Create Visualization? Answer questions (or discover them) Make decisions See data in context Expand memory Support graphical calculation Find patterns Present argument or tell a story Inspire Dr. Ke Zhou (http://www.cs.nott.ac.uk/~pszkz/) G53FIV Why Create Visualization? Answer questions (or discover them) Make decisions s ” o r d See data in context n d w u s a Expand memory a th o r th ocalculation Support graphical i s w tu r e ic Find patterns p “A Present argument or tell a story Inspire Dr. Ke Zhou (http://www.cs.nott.ac.uk/~pszkz/) COMP3021 Summary of Reasons Record information – Blueprints, photographs, seismographs,... Communicate information to others – Share and persuade – Collaborate and revise Analyze data to support reasoning – Find patterns / Discover errors in data – Expand memory – Develop and assess hypotheses Dr. Ke Zhou (http://www.cs.nott.ac.uk/~pszkz/) COMP3021 Record Information Egyptian hieroglyphs Dr. Ke Zhou (http://www.cs.nott.ac.uk/~pszkz/) COMP3021 Record Information E.J. Marey’s sphygmograph (1854) – an instrument which produces a line recording the strength and rate of a person's pulse. Dr. Ke Zhou (http://www.cs.nott.ac.uk/~pszkz/) COMP3021 Communicate: convey information to others Dr. Ke Zhou (http://www.cs.nott.ac.uk/~pszkz/) COMP3021 Share and collaborate DNA Helix Bones in hand (drawn in 1918) Dr. Ke Zhou (http://www.cs.nott.ac.uk/~pszkz/) COMP3021 Persuade: Nightingale’s Graph Dr. Ke Zhou (http://www.cs.nott.ac.uk/~pszkz/) COMP3021 Clarify/Revise: London’s underground map 1926 Dr. Ke Zhou (http://www.cs.nott.ac.uk/~pszkz/) COMP3021 Clarify/Revise: London’s underground map Horizontal, vertical and 45° segments Key insight: topology and relative location of stations 1926 vs. 1987 Dr. Ke Zhou (http://www.cs.nott.ac.uk/~pszkz/) COMP3021 Beer Infographics Dr. Ke Zhou (http://www.cs.nott.ac.uk/~pszkz/) COMP3021 Support reasoning Dr. Ke Zhou (http://www.cs.nott.ac.uk/~pszkz/) COMP3021 Find Patterns: the most powerful brain Dr. Ke Zhou (http://www.cs.nott.ac.uk/~pszkz/) COMP3021 Find Patterns: NYC weather 2200 data points Dr. Ke Zhou (http://www.cs.nott.ac.uk/~pszkz/) COMP3021 Expand Memory Class Exercise 34 x 72 --------- Dr. Ke Zhou (http://www.cs.nott.ac.uk/~pszkz/) COMP3021 Expand Memory Class Exercise 34 x 72 --------- Dr. Ke Zhou (http://www.cs.nott.ac.uk/~pszkz/) COMP3021 Develop and Assess Hypothesis London Cholera Map The closer to the Broad Street water pump, the greater the number of deaths. The information helped convince the public a true sewage London Cholera Map system was needed. Visualization by John Snow, 1854. Dr. Ke Zhou (http://www.cs.nott.ac.uk/~pszkz/) COMP3021 Surprises in Data “The greatest value of a picture is when it forces us to notice what we never expected to see.” John Tukey, 1977 “Contained within the data of any investigation is information that can yield conclusions to questions not even originally asked. That is, there can be surprises in the data...” W. Cleveland The Elements of Graphing Data Dr. Ke Zhou (http://www.cs.nott.ac.uk/~pszkz/) COMP3021 Reasoning / Exploration “If you can articulate very precisely what you’re seeking, visualization likely isn’t your best approach” J. Stasko, EuroVis’14 Exploration Don’t know what you’re looking for Don’t have a priori questions Want to know what questions to ask Dr. Ke Zhou (http://www.cs.nott.ac.uk/~pszkz/) COMP3021 Hans Rosling’s TED talk http://www.ted.com/talks/hans_rosling_shows_the_best_stats_you_ve_ever_seen Dr. Ke Zhou (http://www.cs.nott.ac.uk/~pszkz/) COMP3021 Key Applications of IV I. Record Information II. Communications (Presentation) – Communicate data and ideas – Explain and inform – Provide evidence and support – Influence and persuade III. Reasoning (Analysis) – Explore the data – Assess a situation – Determine how to proceed – Decide what to do Courtesy to J. Stasko on the categorization and part of the slides (EuroVis’14). Dr. Ke Zhou (http://www.cs.nott.ac.uk/~pszkz/) COMP3021 The Visualization Process Dr. Ke Zhou (http://www.cs.nott.ac.uk/~pszkz/) COMP3021 Different Stages of Visualization Dr. Ke Zhou (http://www.cs.nott.ac.uk/~pszkz/) COMP3021 Data transformation – create a structural model (schema), mapping raw data into data tables Visual mapping – create a visual spatial model, transforming data tables into visual structures View Transformations – Create views of the Visual Structures by specifying graphical parameters such as position, scaling, and clipping Dr. Ke Zhou (http://www.cs.nott.ac.uk/~pszkz/) COMP3021 Different Stages of Visualization Visualizing Data by Ben Fry Dr. Ke Zhou (http://www.cs.nott.ac.uk/~pszkz/) COMP3021 Seven Stages: Acquire Obtain the data, whether from a file on a disk or a source over a network Zip codes in the format provided by the U.S. Census Bureau Dr. Ke Zhou (http://www.cs.nott.ac.uk/~pszkz/) COMP3021 Seven Stages: Parse Provide some structure for the data's meaning, and order it into categories. Structure of acquired data, formatted as a data type that we'll handle in a conversion program Dr. Ke Zhou (http://www.cs.nott.ac.uk/~pszkz/) COMP3021 Seven Stages: Filter Remove all but the data of interest. Filter out some data points remain only some data fields Dr. Ke Zhou (http://www.cs.nott.ac.uk/~pszkz/) COMP3021 Seven Stages: Mine Apply methods from statistics or data mining as a way to discern patterns or place the data in mathematical context. Dr. Ke Zhou (http://www.cs.nott.ac.uk/~pszkz/) COMP3021 Seven Stages: Represent Choose a visual model, such as a bar graph, list, or tree. Basic visual representation of zip code data Dr. Ke Zhou (http://www.cs.nott.ac.uk/~pszkz/) COMP3021 Seven Stages: Refine Improve the basic representation to make it clearer and more visually engaging. Using color to refine the representation Dr. Ke Zhou (http://www.cs.nott.ac.uk/~pszkz/) COMP3021 Seven Stages: Interact Add methods for manipulating the data or controlling what features are visible. Zooming in with two digits of the post code (02) Dr. Ke Zhou (http://www.cs.nott.ac.uk/~pszkz/) COMP3021 Interaction is Vital for Exploration Engage in a dialog with your data Employ interaction in a more fundamental manner to strengthen the power of visualization Possible Actions – Select – Abstract/Elaborate – Explore – Filter – Reconfigure – Connect – Encode Yi, et al. "Toward a deeper understanding of the role of interaction in information visualization.” 2007. Dr. Ke Zhou (http://www.cs.nott.ac.uk/~pszkz/) COMP3021 Break Dr. Ke Zhou (http://www.cs.nott.ac.uk/~pszkz/) COMP3021 R Introduction Dr. Ke Zhou (http://www.cs.nott.ac.uk/~pszkz/) COMP3021 What is ? GNU project developed by John Chambers @ Bell Lab (https://www.r-project.org/) Free software environment for statistical computing and graphics Functional programming language written primarily in C, Fortran A lot of data scientists working in the company (such as Google) use R. IDE: R Studio (www.rstudio.com) https://simplystatistics.org/posts/2013-02-15-interview-with-nick- chamandy-statistician-at-google/ Dr. Ke Zhou (http://www.cs.nott.ac.uk/~pszkz/) COMP3021 R f Dr. Ke Zhou (http://www.cs.nott.ac.uk/~pszkz/) COMP3021 CRAN install a package from the command line: – install.packages(“ggplot2”, dependencies = TRUE) http://cran.r-project.org Dr. Ke Zhou (http://www.cs.nott.ac.uk/~pszkz/) COMP3021 Getting Help with R Embedded “help” function in R – help(func), ?func For a topic – help.search(topic), ??topic demo(is.things) search.r-project.org Stack Overflow: – http://stackoverflow.com/tags/R Dr. Ke Zhou (http://www.cs.nott.ac.uk/~pszkz/) COMP3021 Bring Data into R Create csv file Name your variables well – Self-explanatory, unique, lowercase, short-ish, one- word name In R, set the working directory – setwd(“/users/you/R/tutorial”) – What is the working directory? getwd() – What is in the working directory? dir() Read in data Write data Dr. Ke Zhou (http://www.cs.nott.ac.uk/~pszkz/) COMP3021 Read and Write Read in data – CSV files: iris.df