I have data in file.txt which can be expressed by 20000x11 matrix. I do not want to import all of these data. How can I plot graph of the column 1 & column 4?
If the data are comma-delimited and saved as
imports columns 1 and 3, giving:
More information may be found here ("How to Import a Spreadsheet")
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If the file is very large and importing it takes too much memory, you can use external tools to cut the columns you are interested in. You can often call these tools directly from Mathematica, for example
This approach can be significantly faster than