Hi,
Based on user input, I wrote a function that creates a list which
looks like:
> str(list)
List of 4
$ varieties: chr [1:12] "temp.26_time.5dagen_biorep.1" "time.
5dagen_temp.26_biorep.2" "temp.18_time.5dagen_biorep.1" "temp.18_time.
5dagen_biorep.2" ...
$ temp : Factor w/ 2 levels "18","26": 2 2 1 1 2 2 1 1 1 1 ...
$ time : Factor w/ 3 levels "14dagen","28dagen",..: 3 3 3 3 1 1
1 1 2 2 ...
$ biorep : Factor w/ 2 levels "1","2": 1 2 1 2 1 2 1 2 1 2 ...
Now, based on user input as well, I want to dynamically extract data
from list$varieties. Therefore, I wrote a function which generates a
string containing the data extraction conditions which looks like this:
> query <- make.contrast.substring(negative.contrast, list)
Read 1 item
[1] "(list$temp=='18')&(list$time=='14dagen'|list$time=='28dagen'|list
$time=='5dagen')&(list$biorep=='1'|list$biorep=='2')"
Now what I want to achieve is to extract data by doing:
list$varieties[query]
which doesn't work since "query" is a string and object names are not
expanded...
Obviously, manually copying the string like so
list$varieties[(list$temp=='18')&(list$time=='14dagen'|list
$time=='28dagen'|list$time=='5dagen')&(list$biorep=='1'|list
$biorep=='2')]
works perfectly - but I need it to be automated.
I'm quite new to R and used to programming in PHP, so I may just be
"conceptually" confused about how to do this. Any help would be
greatly appreciated.
thanks in advance,
Dries Knapen
********************************************
Dr. Dries Knapen
University of Antwerp
Department of Biology
Ecophysiology, Biochemistry and Toxicology
Groenenborgerlaan 171 - U711, B-2020 Antwerp
Belgium
tel ++32 3 265 33 49
fax ++32 3 265 34 97
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