I have a file with 40,000 data points. In Matlab I can use the plot command to draw the plot:
aaa = Import('file Name');
plot(aaa,mesh)
How do I do it in Mathematica? I tried:
aaa = Import["File Name"]
ListPlot3D[aaa]
but it doesn't work.
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1 Answer
You have two issues here: (1) how to import the data into Mathematica and (2) how to display it.
For the first problem, the simplest answer is: it depends on the format of the data. If the file is one of the supported types, Import has a number of capabilities that can't be beat. If your data is just tab (or, whitespace) delimited, use the "Table" format, as follows:
Import["file name", "Table"]
using the various import options to specify the record and field separators. Alternatively, you can use ReadList, which simply reads in a list of values. If your data is of the form
value value value ... value
etc.
where value is numeric and each line is a separate record, I'd import it using
ReadList["file name", Number, RecordLists -> True]
which loads the file into a rectangular array.
As to the second problem, if your data is a set of triples, i.e. (x, y, z), or just a set of height values, then ListPlot3D should work just fine. If your data is instead of the form (x, y, z, f), where f is the function value at (x, y, z), then you should use ListContourPlot3D instead. You specify which contours you want by using the Contour option. Be warned, ListContourPlot3D may take a while to generate the plot depending on how large your data set is. Also, it can be a memory hog, on my machine (G4, MacOS 10.4, 2 GB) a ListContourPlot3D of an 80 x 80 x 80 grid can easily take 500 MB.
