R Language Learning Notes

How to do group by for Dataframe, need to use data.frame table, etc.

Http://stackoverflow.com/questions/25293045/count-number-of-rows-in-a-data-frame-in-r-based-on-group

mydf#    ID MONTH.YEAR VALUE# 1 110  JAN. 2012  1000# 2 111 JAN. 2012 2000# 3 121 FEB. 2012 3000# 4 131 FEB. 2012 4000# 5 141 MAR. 2012 5000

Here's the calculation of the number of rows per group, in the output display formats:

Table(Mydf$MONTH. Year)## FEB. # 2 2 1data.frame (table (MYDF $month. Year# Var1 freq# 1 FEB . 2# 2 JAN 2# 3 MAR 1 
 
 
 first column ascending, second column descending 
 > A[order (a[,1],-a[,2]),] 
      [,1] [, 2] [, 3] 
 [1,]    2     7   14 
 [2,]    2    6   13 
 [3,]    3    8& nbsp  10 
 [4,]    4    9   11 
 [5,]    5    6   12 
 span>                 

R language Learning notes