Category Archives: try this

Easy version control for single files: RCS

Version control is a wonderful invention: it allows you to keep track of what has changed in a file (or directory hierarchy) between each revision.  When you have made some changes you “check in” (or “commit”) and leave a quick … Continue reading

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a bit of knowledge of regular expressions

Today a collaborator who is working toward more automation in her ordinary computing work asked me how to use the amazing command-line browser wget to get the images out of a web page. wget has options to grab a whole web site: … Continue reading

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Using PyEphem to get the ground coordinates of a satellite

The PyEphem package is pretty amazing. The tutorial will show you many things. I had a simple application for it: I needed to take a satellite’s orbital information and get the ground longitude/latitude under that satellite at a given time. A … Continue reading

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starting with hdf5 — writing a data cube in C

pre(r)amble Let us start using hdf5 to write out a “data cube” — in our example a series of scalar values f(x, y, z). hdf5 is a library written in C but it can be called from many programming languages. … Continue reading

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volume visualization — mayavi and mayavi2

Some programs are truly delightful; I have long had a list of those that charmed me. One of these was  mayavi, the volume visualization program.  Volume visualization is quite different from what people think of as “3D graphics” — a … Continue reading

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