Various Minutae

Here is a script for making nice contour plots of data with gnuplot. This can be used (with appropriate modifications, which are clear in the script) to plot functions of two variables or (without any modification to the version here) data files. It is best that the data files be in "grid data" format, as defined by the gnuists. This means that you have a blank line in your file after each row/column of the grid is traversed, followed by the next row/column. And the entries in the column/row have to be consecutive and evenly spaced, and the grid must be exactly rectangular. If you can't satisfy this, you have to use the dgrid3d option (see script). This requires gnuplot v4.2 or higher.

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Here is a script for making a yet fancier contour plot, with values written along the contours. This script also needs a dependent gawk script called cont.sh, which can be found here. This is the procedure used to make the NO₃ radical contour plot on the homepage.

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How to make a color transparent (for making slides). This is useful if you want to use, for example, a spectrum in the literature to overlay your calculated stick spectrum :)

1. Make a screenshot of the image in the journal/pdf/etc.

2. Load this into photoshop

3. Go to Layer -> New -> Layer from Background

click "ok" (color should be "none")

4. Go to Select -> Color Range

click on the color that you want to remove (white, usually)

5. Go to Layer -> Layer Mask -> Hide Selection

voila. It goes away. Save the file as a png and import it into powerpoint.

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command D deselects, x swaps the colors

quick selection tool (near top), click on color, click on select, click "similar", click on "edit", click fill - color

image -> adjustments -> hue saturation is awesome