Data grouping and sub-grouping by column variable in R
问题 I am working on data collection by R on Win7. The given data is: var1 var2 value I need to do grouping by var1 and then for each var1 , do grouping by var2. Then, the output is column vectors of values that are associated with the same var1 and var2. Here, var1 and var2 are like keys. Example, var1 var2 value 1 56 649578 2 17 357835 1 88 572397 2 90 357289 1 56 427352 2 17 498455 1 88 354623 2 90 678658 The result should be var1 var2 value 1 56 649578 1 56 427352 1 88 354623 1 88 572397 2 17