[R] extract required data from already read data

[David Winsemius]

On May 7, 2010, at 1:04 AM, Mohan L wrote:

> Hi all,
>
> I have data like this:
>
>> sample <- read.csv(file="sample.csv",sep=",",header=TRUE)
>> sample
>
>   stdate   Domain    sex age Login
> 1  01/11/09    xxx FeMale  25     2
> 2  01/11/09    xxx FeMale  35     4
> 3  01/11/09    xxx   Male  18    30
> 4  01/11/09    xxx   Male  31     3
> 5  02/11/09    xxx   Male  32    11
> 6  02/11/09    xxx   Male  31     1
> 7  02/11/09    xxx FeMale  29     1
> 8  02/11/09    xxx FeMale  23     5
> 9  03/11/09    xxx FeMale  25     9
> 10 03/11/09    xxx FeMale  35     6
> 11 03/11/09    xxx   Male  18     3
> 12 03/11/09    xxx   Male  31     0
> 13 04/11/09    xxx   Male  32    25
> 14 04/11/09    xxx   Male  31     1
> 15 04/11/09    xxx FeMale  29     0
> 16 01/11/09    yyy FeMale  25     2
> 17 01/11/09    yyy FeMale  35     4
> 18 01/11/09    yyy   Male  18    30
> 19 01/11/09    yyy   Male  31     3
> 20 02/11/09    yyy   Male  32    11
> 21 02/11/09    yyy   Male  31     1
> 22 02/11/09    yyy FeMale  29     1
> 23 02/11/09    yyy FeMale  23     5
> 24 03/11/09    yyy FeMale  25     9
> 25 03/11/09    yyy FeMale  35     6
>
>
> I have done the graph for all the data. Now I want to get data from
> particular Domain and Sex from above data, then I need to do the  
> calculation
> , eg :

I suspect you want to be working on an object like :

subset(sample, Domain=="xxx" & sex == "Male")

>
> # if both are true
> if(Domain == xxx && sex==FeMale)

The && operator will not give you what you want. It only returns a  
single value and is unusable for selecting subsets. Go back and read  
the introductory material. This is explained.

>
> I need the data in another variable, like this
>
> 1  01/11/09    xxx FeMale  25     2
> 2  01/11/09    xxx FeMale  35     4
> 3  02/11/09    xxx FeMale  29     1
>
> I have failed to achieve it .  any help would greatly appreciated.
>
> Thanks & Rg
> Mohan L

David Winsemius, MD
West Hartford, CT