[R] Sampling dataframe

[Ronaldo Reis Júnior]

Hi,

I have a table like that:

> datatest     
   var1 var2 var3
1     1    1    1
2     3    1    2
3     8    1    3
4     6    1    4
5    10    1    5
6     2    2    1
7     4    2    2
8     6    2    3
9     8    2    4
10   10    2    5

I need to create another table based on that with the rules:

take a random sample by var2==1 (2 sample rows for example):

   var1 var2 var3
1     1    1    1
4     6    1    4

in this random sample a get the 1 and 4 value on the var3, now I need to 
complete the table with var1==2 with the lines that var3 are not select on 
var2==1

The resulting table is:
   var1 var2 var3
1     1    1    1
4     6    1    4
7     4    2    2
8     6    2    3
10   10    2    5

the value 1 and 4 on var3 is not present in the var2==2.

I try several options but without success. take a random value is easy, but I 
cant select the others value excluding the random selected values.

Any help?

Thanks
Ronaldo


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          de modo que ele possa, finalmente, se tornar famoso.

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