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Spectrogram
A spectrogram is a time-frequency representation that shows how the spectral content of a signal varies with time. In Fig. 1 the spectrogram of the German sentence “Achte auf die Autos” is shown. Fig....
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Matlab colorbar with Gnuplot
This time another colormap plot. If you are using Matlab or Octave you are probably be familiar with Matlabs nice default colormap jet. Fig. 1 Photoluminescence yield plotted with the jet colormap from...
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Multiple lines with different colors
Most of you will probably know the problem of visualizing more than two dimensions of data. In the past we have seen some solutions to this problem by using color maps, or pseudo 3D plots. Here is...
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Defining a palette with discrete colors
In one off the last entries we defined a color palette similar to the default one in Matlab. Now we will use a color palette with only a few discrete colors, as shown in Fig. 1. This can be useful if...
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Interpolation of heat maps
We discussed already the plotting of heat maps at more than one occasions. Here we will add the possibility to interpolate the data in a heat map figure. Fig. 1 A simple heat map (code to produce this...
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Default color map
As you may have noted, gnuplot and Matlab have different default color maps. Designing such a default map is not easy, because they should handle a lot of different things (Moreland, 2009): – The map...
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Color maps from colorbrewer
If you are looking for nice color maps which are especially prepared to work with cartographic like plots you should have a look at colorbrewer2.org. On that site hosted by Cynthia Brewer you can pick...
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Matlab colorbar parula with gnuplot
Some time ago I discussed how to get the jet colormap from Matlab in gnuplot. Since Matlab R2014b jet is no longer the default colormap. Now parula is the new default colormap. It was introduced...
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Matplotlib colormaps
Matplotlib has four new colormaps called viridis, plasma, magma, and inferno. Especially viridis you might have seen already as this will be the new default in Matplotlib 2.0. They are freely available...
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Circular heat map
Suppose you have a large circular container filled with sand and measure its density at different positions. Now the goal is to display your measurements as a heat map extrapolated from your...
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