Hi:
Perhaps this might be useful:
tst <- read.table(textConnection("
+ plate.id well.id Group HYB rlt1
+ 1 P1 A1 Control SKOV3hyb 0.190
+ 2 P1 A2 Control SKOV3hyb 0.210
+ 3 P1 A3 Control SKOV3hyb 0.205
+ 4 P1 A4 Control SKOV3hyb 0.206
+ 5 P1 A5 Control SKOV3hyb 0.184
+ 385 P1 A1 ovca SKOV3hyb 0.184
+ 386 P1 A2 ovca SKOV3hyb 0.229
+ 387 P1 A3 ovca SKOV3hyb 0.214
+ 388 P1 A4 ovca SKOV3hyb 0.226
+ 389 P1 A5 ovca SKOV3hyb 0.217"), header = TRUE)
tst2 <- reshape(tst, idvar = c('plate.id', 'well.id'), timevar = 'Group',
direction = 'wide')
tst2
plate.id well.id HYB.Control rlt1.Control HYB.ovca rlt1.ovca
1 P1 A1 SKOV3hyb 0.190 SKOV3hyb 0.184
2 P1 A2 SKOV3hyb 0.210 SKOV3hyb 0.229
3 P1 A3 SKOV3hyb 0.205 SKOV3hyb 0.214
4 P1 A4 SKOV3hyb 0.206 SKOV3hyb 0.226
5 P1 A5 SKOV3hyb 0.184 SKOV3hyb 0.217
tst2$rlt1.diff <- rlt1.ovca - rlt1.Control
reshape() is reshaping the data based on plate.id * well.id combinations, so
the observations in Control and ovca should match on those two keys..
HTH,
Dennis
On Mon, Sep 27, 2010 at 12:47 PM, 1Rnwb <sbpuro...@gmail.com> wrote:
>
> Hello
>
> I have a data set like below:
> plate.id well.id Group HYB rlt1
> 1 P1 A1 Control SKOV3hyb 0.190
> 2 P1 A2 Control SKOV3hyb 0.210
> 3 P1 A3 Control SKOV3hyb 0.205
> 4 P1 A4 Control SKOV3hyb 0.206
> 5 P1 A5 Control SKOV3hyb 0.184
> 385 P1 A1 ovca SKOV3hyb 0.184
> 386 P1 A2 ovca SKOV3hyb 0.229
> 387 P1 A3 ovca SKOV3hyb 0.214
> 388 P1 A4 ovca SKOV3hyb 0.226
> 389 P1 A5 ovca SKOV3hyb 0.217
> 390 P1 A6 ovca SKOV3hyb 0.207
>
>
> each plate.id contains 384 readings for Group=="Control" and the same
> plate.id will contain 384 readings for Group=='ovca' to give a total of
> 768
> values for P1 and so on for other plate ID's. I have to take the subtract
> the values of rlt1 colum between the two groups based on Plate ID.
>
> currently I am using
> > newdat2$diff<-(newdat2[1:5,5]-newdat2[6:10,5])/newdat2[1:5,5]*100
> > newdat2
> plate.id well.id Group HYB rlt1 diff
> 1 P1 A1 Control SKOV3hyb 0.190 3.157895
> 2 P1 A2 Control SKOV3hyb 0.210 -9.047619
> 3 P1 A3 Control SKOV3hyb 0.205 -4.390244
> 4 P1 A4 Control SKOV3hyb 0.206 -9.708738
> 5 P1 A5 Control SKOV3hyb 0.184 -17.934783
> 385 P1 A1 ovca SKOV3hyb 0.184 3.157895
> 386 P1 A2 ovca SKOV3hyb 0.229 -9.047619
> 387 P1 A3 ovca SKOV3hyb 0.214 -4.390244
> 388 P1 A4 ovca SKOV3hyb 0.226 -9.708738
> 389 P1 A5 ovca SKOV3hyb 0.217 -17.934783
>
> I have tried
> apply(newdat2, 1, function(x) tapply(x, plate.id,
> newdat2$Control-newdat2$ovca)))
>
> I am looking for a more simple way to calculate the percent difference
> between the each value (based on well.id) for the two groups for 100's of
> plate.ids.
>
> I would appreciate help in getting this solved.
> Thanks
>
> --
> View this message in context:
> http://r.789695.n4.nabble.com/subtraction-based-on-two-groups-in-a-dataframe-tp2716104p2716104.html
> Sent from the R help mailing list archive at Nabble.com.
>
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