[R] delete rows

[Sundar Dorai-Raj]

Sonchawan,
I have an answer for your first question:

> I would like to know how to delete some rows?
> Suppose I have a large data frame look something like this:
> 
> x1      x2       x3     ..............
> a        1      0.45
> b        1      0.41
> c        0      0.43
> a        1      0.39
> d        1      0.40
> e        0      0.41
> r        1      0.42
> a        0      0.46
> .        .       ..
> 
> I would like to have another data frame which has all columns like the
> original one but if any rows have the same values in x1, then keep only the
> first row and delet the rest. Is it any way to make it look like this?
> 
> x1      x2       x3     ..............
> a        1      0.45
> b        1      0.41
> c        0      0.43
> d        1      0.40
> e        0      0.41
> r        1      0.42
> .        .       ..

SOLUTION:
> df <- data.frame(x1=gl(4,2,labels=letters[1:4]),
+                  x2=gl(2,4,labels=0:1),
+                  x3=rnorm(8))
> df
  x1 x2          x3
1  a  0  0.08317423
2  a  0 -1.10762737
3  b  0  0.71998683
4  b  0 -1.61450894
5  c  1 -0.07808250
6  c  1  0.36657481
7  d  1  0.26291955
8  d  1 -0.65862664
> aggregate(df$x3,list(x1=df$x1,x2=df$x2),function(x) x[1])
  x1 x2           x
1  a  0  0.08317423
2  b  0  0.71998683
3  c  1 -0.07808250
4  d  1  0.26291955
> 

> 
> Another question is I downloaded data from Oracle database to R which looks
> like this:
>    DATE,'yyyy,ww'  TRD_AMT
> 1    2001,01       57.99330
> 2    2001,01       59.52926
> 3    2001,03       61.31018
> 4    2001,04       59.07095
> 5    2001,05       62.29583
> 6    2001,06       63.96679
> 
> It's weekly data and I would like to plot it. How could I do that?
> 

Can't help you with the second one off the top of my head.

Sundar


-- 

Sundar Dorai-Raj, Ph.D.
Statistical Methods Engineer
PDF Solutions, Inc.
Richardson TX
(972) 889-3085 x216
(214) 392-7619 cell
sundard at pdf.com
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