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Additional notes to add #8

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GreatEmerald opened this issue Jan 15, 2017 · 1 comment
Open

Additional notes to add #8

GreatEmerald opened this issue Jan 15, 2017 · 1 comment

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@GreatEmerald
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Some notes that came up:

  • Dropbox is rather weird with its download capabilities. By default the link does not work: the file you get is an HTML file. But if the end is changed to ?dl=1, then you get the right file, provided that you are on Linux (the file gets corrupt on Windows). The workaround on Windows is to change the file creation mode. Either way it's not very cross-platform.
    • Noting that people should try to work within the Linux VMs might be a good idea; some thought it was just for the intro lesson, and then found problems running their Windows-tested scripts in the VMs
  • Some issues running plotRGB, it would complain about values out of range 0:255. That requirement makes sense for actual RGB values, but is the function really not smart enough to figure out value scaling?
  • Differences between plot and spplot might be worth pointing out
  • Some students had trouble thinking with functions: what should be in a function, what should be in main.R, what are function arguments, etc.
  • overlay with filename argument specified makes the resulting variable forget layer names. They can be regained with names(newraster) = names(oldraster)
@GreatEmerald
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This whole list was true this year around as well. This should really be improved.

There are a lot of gotchas in the exercise, which are annoying for everyone involved; it's not obvious that plotRGB() behaves counter-intuitively by default (and throwing weird errors) unless you pass stretch="lin" into it, so that it works just fine. This not only confuses students, but also teaching staff, because we forget (or never knew that in the first place), and then assume it's not possible/values need to be stretched manually/etc. which doesn't actually help students. So just mentioning that in the tutorial would save a lot of frustration. Students complained that everyone runs into the same issues and everyone needs to ask, which is not very efficient.

In general, the exercise may be too difficult, and for the wrong reasons. It's a lot of busywork and dealing with weird errors, and not a whole lot of actually doing cool stuff. Solving this list should at least make it reasonably long and less frustrating.

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