I would like to combine columns into one. But i don't know how to do so. My data set is like this: Period ColA ColB ColC 1 1 1 2 1 3 2 1 2 2 3 5 3 8 And i would like to combine the same column of period into one. like this: Period ColA ColB ColC 1 1 2 3 2 1 2 3 5 8 i have tried many times but it still doesn't work.
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