Hi,

I used a tool to perform differential expression analysis on my microarray data sets,

The output is something like below

```
ProbesetID logFC AveExpr t P.Value adj.P.Val B
1769308_at 1.89394112596704 10.5871328585202 16.4749776727376 3.68669391559684e-10 2.6623530112e-08 13.7014616531283
1769311_at -0.115715211915935 10.5999601204582 -1.12002479223092 0.282752344869474 0.382582735789368 -7.1722215976202
1769312_at 0.131966902231916 9.02503563963962 1.5364411821642 0.148147122010043 0.230066458270885 -6.6497072352879
```

Sorry, may someone please tell me how I can select only the probsets with a desire fold change or P.Value?

For example probesets more than 1

Thank you so much

thank you,

but I am too weak in R and can't figure out easily what to type in R

Did you read the help for subset by typing

`help("subset")`

? Notice that the help for R functions usually includes one or more examples at the end of the help page which you should read and type into R by hand. Also, a quick google search turns up: http://www.r-bloggers.com/subsetting-data/ and http://www.ats.ucla.edu/stat/r/modules/subsetting.htm among many others. If this doesn't help, then I would advise an online course in R before proceeding, as subsetting is a basic necessity for doing any work in R.I assume the above output is from topTable, right?

for instance(assuming that my above notion is correct)--as you have a data.frame, let's called it dat, which has the output of topTable. Then, you could use something like the following:

Hope that helps,

Efstathios

then first thing you spend your time on is R.