Plotting a 2D grid "spectrogram" from a large .csv file

Question

I'm aware of this question here that uses MatrixPlot to plot the spectrogram of a sound file, but it's too complicated for me to understand, unfortunately.

My file consists of 1000 lines and several thousand columns of data that represent the intensity of a signal, taken at identical time ticks after a trigger signal has occurred. As an example, the first few columns and lines look like this:

0, -0.028346,   -0.028346,  -0.028346
1, -0.028346,   -0.028346,  -0.028346
2, -0.028346,   -0.028346,  -0.028346
3, -0.028346,   -0.028346,  -0.028346
4, -0.027056,   -0.027056,  -0.028346

My idea was to:

Import my file with mydata = Import["myfile.csv", "CSV"]
determine the minimum and maximum of this data to have reference values with min = Min[Abs[data]]; and max=Max[Abs[data]]
make a plot as follows: every column should be represented by a line of dots/pixels, color-coded to represent the intensity of the signal (What function would I use here?)
stack all these lines, aligned with each other, on top of each other, such that the time/columns from mydata basically goes from bottom to top

Am I on the right track or should I use something else instead?

EDIT: found an easy answer myself that I will post below.

Are you sure your time would not be better spent trying to understand the existing solution, rather than trying to reinvent the wheel? Also, you will want to include a complete data set if you can. — MarcoB, Dec 09 '19 at 16:37
Does this answer your question? Computing and plotting a spectrogram in Mathematica — bbgodfrey, Dec 15 '19 at 17:07

score 1 · Accepted Answer · answered Dec 12 '19 at 10:26

So, here's a solution that I found myself that is rather easy to implement and can be adapted to your needs.

Import your data with

data = Import["myfile.csv"];

Then, simply use ArrayPlot or MatrixPlot

ArrayPlot[data,
ColorFunction -> (ColorData["SunsetColors"]),
ColorFunctionScaling -> True]

One can certainly play around with color parameters, graphic scaling etc., but that is quite individually different, so I'll omit it here and just share the image that I got out of my dataset. The two artifact lines are due to some empty columns in my dataset.

Plotting a 2D grid "spectrogram" from a large .csv file

1 Answers1