[R] Create sequential vector for values in another column

[PIKAL Petr]

Hi

I named your data test

test$x<-1
test$x<-unlist(lapply(split(test$x, test$id.name), cumsum))
> test
   id.name x
1   123.45 1
2   123.45 2
3   123.45 3
4   123.45 4
5   234.56 1
6   234.56 2
7   234.56 3
8   234.56 4
9   234.56 5
10  234.56 6
11  234.56 7
12  345.67 1
13  345.67 2
14  345.67 3
15  456.78 1
16  456.78 2
17  456.78 3
18  456.78 4
19  456.78 5
20  456.78 6
21  456.78 7
22  456.78 8
23  456.78 9
>
Two comments:
This works only when your data are sorted
Beware of FAQ 7.31

Regards
Petr


> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of Steven Ranney
> Sent: Friday, October 11, 2013 3:26 PM
> To: r-help at r-project.org
> Subject: [R] Create sequential vector for values in another column
> 
> Hello all -
> 
> I have an example column in a dataFrame
> 
> id.name
> 123.45
> 123.45
> 123.45
> 123.45
> 234.56
> 234.56
> 234.56
> 234.56
> 234.56
> 234.56
> 234.56
> 345.67
> 345.67
> 345.67
> 456.78
> 456.78
> 456.78
> 456.78
> 456.78
> 456.78
> 456.78
> 456.78
> 456.78
> ...
> [truncated]
> 
> And I'd like to create a second vector of sequential values (i.e., 1:N)
> for each unique id.name value.  In other words, I need
> 
> id.name  x
> 123.45   1
> 123.45   2
> 123.45   3
> 123.45   4
> 234.56   1
> 234.56   2
> 234.56   3
> 234.56   4
> 234.56   5
> 234.56   6
> 234.56   7
> 345.67   1
> 345.67   2
> 345.67   3
> 456.78   1
> 456.78   2
> 456.78   3
> 456.78   4
> 456.78   5
> 456.78   6
> 456.78   7
> 456.78   8
> 456.78   9
> 
> The number of unique id.name values is different; for some values,
> nrow() may be 42 and for others it may be 36, etc.
> 
> The only way I could think of to do this is with two nested for loops.
> I tried it but because this data set is so large (nrow = 112,679 with
> 2,161 unique values of id.name), it took several hours to run.
> 
> Is there an easier way to create this vector?  I'd appreciate your
> thoughts.
> 
> Thanks -
> 
> SR
> Steven H. Ranney
> 
> 	[[alternative HTML version deleted]]
> 
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