Gosh there are a lot of these programs, aren't there? For some reason I find it really hard to read these tree map visualisations. I know the theory and all that, but for me they just aren't an intuitive way of displaying that kind of information. For me a radial graph (i.e. pie chart like) is much easier to grok - I don't even have to think about it, I just get it. Seems like there must be plenty of people who don't…
Then earlier this year, I happened to use flame graphs for visualizing profiling data.
This is when I realized I hadn't quite understood flame graphs. It became obvious that you can use flame graphs for visualizing the SPACE used by a tree hierarchy as well as TIME.
I googled and Brendan Gregg already wrote about this!
http://www.brendangregg.com/blog/2017-02-05/file-system-flam...
http://www.brendangregg.com/blog/2017-02-06/flamegraphs-vs-t...
So from now on, I believe I will use flame graphs instead of treemaps to visualize this space.
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Details: A common point of confusion for flame graphs is that the Y axis is "time elapsed". (Chrome dev tools has a "flame chart" where the Y axis is time elapsed, but it's not a flame graph.)
The Y axis is "cumulative time used", and the X axis is the call stack. Combining call stacks sampled at different times gives you a TREE, because a given function calls multiple functions.
So if that's clear, it should be clear why flame graphs can be used instead of treemaps. They are the same visualization! And flame graphs have the benefit that they use a one spatial dimension to represent quantity, rather than two. TreeMaps have the same problem as pie charts -- human perception isn't good at measuring areas.
Also, with treemaps, you have error due to the inability to represent a internal directory of zero size (you need some space for the label). Flame Graphs don't have this problem because directories are stacked on the Y axis.