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nicolas777
4 Posts |
 Posted - 03/31/2010 : 3:22:11 PM
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Origin Pro 8 SR4
Ver 8.0951 (B951)
1. I have one question about the peak analyzer used in order to find peaks.
In the "Find peaks Page" there is "the peak filtering group".
A threshold can be defined, which is a percentage but a percentage of what ?
2. I'm trying to used the X-function pkfind in a LabTalk algorithm.
It is a possible to set a threshold value in the same way as in the peak analyzer, but it is not a percentage it is an absolute value. Nonetheless, some of the peaks over this threshold are still left out.
3. If using identical parameters and methods, are the Peak Analyzer and the X-function pkfind processing similarly ? the results provided by the peak analyzer seem more reasonable and understandable than the one provided by the pkFind function.
thanks
nicolas |
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Deanna
China
Posts |
Posted - 03/31/2010 : 10:53:11 PM
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quote:
1. I have one question about the peak analyzer used in order to find peaks.
In the "Find peaks Page" there is "the peak filtering group".
A threshold can be defined, which is a percentage but a percentage of what ?
Sorry, the information in the old document is not complete. In Origin 8.1's document, this is clearly explained:
Threshold Height(%)
This text box is available only when Height is selected in the Filter Method drop-down list. You can use it to specify the minimum height of the found peaks. It is a percent of a reference value, which is defined as follows:
First, get the maximum value and the minimum value of the spectrum (if a baseline has been subtracted from it, use the spectrum after subtraction). Then compare the absolute values of the maximum value and the minimum value. The greater one will be regarded as the reference value of the Threshold Height.
quote:
2. I'm trying to used the X-function pkfind in a LabTalk algorithm.
It is a possible to set a threshold value in the same way as in the peak analyzer, but it is not a percentage it is an absolute value. Nonetheless, some of the peaks over this threshold are still left out.
The algorithm to find peaks in these tools are in fact the same. The main differences are 1) the absolute value and percentage difference, which you have already pointed out; 2) baseline.
I did some simple tests but I could not see any peaks over the threshold were left out. I am thinking that this problem might be data-specific. Please send us your data so that we can look into it to find out what the problem is.
This web page provides instructions on how to send us data: http://originlab.com/index.aspx?s=1&lm=123&pid=752
quote:
3. If using identical parameters and methods, are the Peak Analyzer and the X-function pkfind processing similarly ? the results provided by the peak analyzer seem more reasonable and understandable than the one provided by the pkFind function.
As mentioned above, their processing are very similar. However, the different treatment of baseline might affect the result of peak finding.
Deanna
OriginLab Technical Services |
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peak analyzer and X-Function pkfind