QUESTION
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?
ANSWER
If the data are comma-delimited and saved as myfile.txt then
data =Import["C:\\Users\\md\\Desktop\\myfile.txt", {"Data", {All}, {1, 3}}];
imports columns 1 and 3, giving:
(*{{"a1", "a3"}, {"b1", "b3"}, {"c1", "c3"}, {"d1", "d3"}}*)
For comparison,
Import["C:\\Users\\md\\Desktop\\myfile.txt", {"Data"}]
gives
(*{{"a1", "a2", "a3", "a4", "a5"}, {"b1", "b2", "b3", "b4",
"b5"}, {"c1", "c2", "c3", "c4", "c5"}, {"d1", "d2", "d3", "d4",
"d5"}} *)
More information may be found here ("How to Import a Spreadsheet")
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