[R] Find peaks in dataset(x,y) and area for each peak

[Laurent Gatto]

Dear Ramya

On 18 February 2011 05:08, Ramya <ramya.victory at gmail.com> wrote:
>
> http://r.789695.n4.nabble.com/file/n3312061/x_and_y_values.txt
> x_and_y_values.txt
>
>
> I have the absorbance values form HPLC Chromatogram. I need to find the
> peaks in datapoints and area under each peak.
>
> I am not sure how how to find the peaks, I tried couple of libraries and
> peak function but they return me a list of values which when computed from
> area turns out to be huge nnumbers. In the dataset I know there are 4 peaks
> but i couldnt find through R.

Using DrawChromatogram from OrgMassSpecR [1] for the main peak:

> library(OrgMassSpecR)
> dd <- read.csv("x_and_y_values.txt",sep="\t")
> DrawChromatogram(dd$x,dd$y,range=list(start="490",stop="580"))
  retentionTime peakArea apexIntensity
1         528.5  1276508         65845

seems to work fine for me.

[1] http://orgmassspecr.r-forge.r-project.org/

> getPeaks method was kind of promising but i am not sure how to use it.

Which getPeak do you mean? sessionInfo() would have given us some hints.

Hope this helps,

Laurent

> Any help would be appreciated.
>
> Thanks
> Ramya
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-- 
[ Laurent Gatto | slashhome.be ]