[R] Loop With Dates

[Phillip Heinrich]

With the data snippet below I’m trying to increment the “count” vector by one each time the date changes.  

         Date count
1   2018-03-29     1
2   2018-03-29     1
3   2018-03-29     1
81  2018-03-30     1
82  2018-03-30     1
83  2018-03-30     1
165 2018-03-31     1
166 2018-03-31     1
167 2018-03-31     1
 
     
            >  
     


I can get count to change when the date changes with the following code:

test2 <- transform(test2,
+                   count = ifelse(Date == lag(Date,1),count,count+1))
> test2
          Date count
1   2018-03-29    NA
2   2018-03-29     1
3   2018-03-29     1
81  2018-03-30     2
82  2018-03-30     1
83  2018-03-30     1
165 2018-03-31     2
166 2018-03-31     1
167 2018-03-31     1
 
     
           

     


...but I want all three March 30 rows to have a count of 2 and the March 31 rows to be equal to 3.  Any suggestions?

Thanks.
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