| Finding peak with cgHistoplot and bin confusion [message #87111] |
Wed, 08 January 2014 05:39  |
rjp23
Messages: 97
Registered: June 2010
|
Member |
|
|
I'm using cgHistoplot with the binsize value set like so:
cgHistoplot, data, binsize=100, xrange=[0, 8000]
Is there a simple way to find the x value where the histogram peaks?
I thought using the histdata keyword would have worked and then something like find=where(histdata EQ max(histdata)).
The problem though is then knowing which bin that subscript refers to. I assumed because I specify xrange starting from 0 then my first bin would be 0-99. However, if I use the omin keyword it returns a value of 698.045. Does that mean by first bin is 600-699? or 698.045-797.045?
Cheers
|
|
|
|
| Re: Finding peak with cgHistoplot and bin confusion [message #87112 is a reply to message #87111] |
Wed, 08 January 2014 05:59  |
David Fanning
Messages: 11724
Registered: August 2001
|
Senior Member |
|
|
rjp23@le.ac.uk writes:
>
> I'm using cgHistoplot with the binsize value set like so:
>
> cgHistoplot, data, binsize=100, xrange=[0, 8000]
>
> Is there a simple way to find the x value where the histogram peaks?
>
> I thought using the histdata keyword would have worked and then something like find=where(histdata EQ max(histdata)).
>
> The problem though is then knowing which bin that subscript refers to. I assumed because I specify xrange starting from 0 then my first bin would be 0-99. However, if I use the omin keyword it returns a value of 698.045. Does that mean by first bin is 600-699? or 698.045-797.045?
I would do something like this:
cgHistoplot, data, binsize=100, xrange=[0, 8000], HistData=d
maxValue = Max(d, binNumber)
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.idlcoyote.com/
Sepore ma de ni thue. ("Perhaps thou speakest truth.")
|
|
|
|
| Re: Finding peak with cgHistoplot and bin confusion [message #87113 is a reply to message #87112] |
Wed, 08 January 2014 06:33 |
rjp23
Messages: 97
Registered: June 2010
|
Member |
|
|
On Wednesday, January 8, 2014 1:59:29 PM UTC, David Fanning wrote:
>
> I would do something like this:
>
>
>
> cgHistoplot, data, binsize=100, xrange=[0, 8000], HistData=d
>
> maxValue = Max(d, binNumber)
>
Hi David,
Sorry I don't think I explained very well. What you've posted there is just the equivalent of find=where(histdata EQ max(histdata)) isn't it?
What is causing me trouble is then using the returned bin subscript to get the correct bin value.
I think my problem is that I assumed that the first bin was at the bottom of my xrange but it's actually at the bottom of my data range (I think?).
If I do this it looks like it works to get to the middle of the bin in which the distribution peaks:
peak=omin+binsize*find+binsize/2.
|
|
|
|
| Re: Finding peak with cgHistoplot and bin confusion [message #87115 is a reply to message #87113] |
Wed, 08 January 2014 09:09 |
Phillip Bitzer
Messages: 223
Registered: June 2006
|
Senior Member |
|
|
According to the documentation, xrange is passed to the plot command. You're probably wanting mininput/maxinput, not xrange:
http://www.idlcoyote.com/idldoc/cg/cghistoplot.html
But more to the point, you can always get the locations of the bins through a keyword:
cgHistoplot, data, binsize=100, LOCATIONS=loc, HISTDATA=h
maxHisto = MAX(h, binInd)
print, loc[binInd]
Keep in mind that the locations are the starting point of the bins. You might want to use the center of the bin for reporting purposes.
|
|
|
|
comp.lang.idl-pvwave archive
Members
Search
Help
Login
Home
