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ashildfr
Norway
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 Posted - 10/20/2008 : 12:50:29 AM
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Hi,
I have a set of measurements of (r,z) values taken at angles from theta = 0 to theta = 340 degrees, in steps of 10 degrees.
I would very much like to represent these (r,z) values in a contour plot with polar coordinates in stead of cartesian coordnates.
It seems impossible to do so with the 3D contour plot which accepts only one z coulumn. Do I have to convert the r, theta base to cartesian and somehow into a matrix and plot as a contour plot in cartesian?? This will be rather akward. Any quick fix on this one? |
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Deanna
China
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snowli
USA
1381 Posts |
Posted - 10/22/2008 : 4:04:16 PM
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Hello,
Which version of Origin are you using?
In Origin 8, we support both Polar Contour theta(X) r(Y) and Polar Contour r(X) theta(Y). You can put theta, r, Z values in worksheet columns and set the column as X, Y and Z respectively.
Then highlight the columns and choose Plot: Contour: theta(X) r(Y) Z Ploar Contour menu.
For your case, Since your theta is taken at angles from theta = 0 to theta = 340 degrees, in steps of 10 degrees.
You can put r, Z in col B and C. Set Column Value of col(A) to be (i-1)*10 and then do the plot.
Or you can put r, z in col B and C. Then set sampling interval of col B to be (intial X value is 0. X Increment = 10). Then highlight col B and C to plot.
Thanks, Snow Li
OriginLab Corp.
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ashildfr
Norway
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Posted - 10/23/2008 : 06:57:12 AM
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Hi, I am using Origin 8.
However the problem is, that I have a "matrix" with z-values, not only one column. That is, one new column of z values for each degree value....
Ashild |
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snowli
USA
1381 Posts |
Posted - 10/23/2008 : 09:25:36 AM
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Hi,
So both your r and theta values are evenly spaced in Matrix right?
If so, you can use Matrix: Convert to Worksheet menu to convert the Matrix to XYZ worksheet.
Then you can use the Plot menu to plot Polar Contour.
Thanks, Snow |
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easwar
USA
1964 Posts |
Posted - 10/27/2008 : 09:48:35 AM
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Hi Ashild,
Looks like what you have is multiple columns of data in a worksheet "arranged like a matrix"...and yes the r-theta-z contour plot requries the data to be in three columns instead.
So you need to rearrange your "matrix like data" to R-Theta-Z columns. If you patch to SR4, there is a new menu item "Worksheet->Convert to XYZ". You can then plot the polar contour plot from the rearranged three-column ata. Please try that, and if that does not do it, please send your data to tech support so we can see how the data is organized
Easwar
OriginLab
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ashildfr
Norway
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Posted - 10/28/2008 : 11:04:42 PM
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Hi,
Thanks to 'easwar' and 'snowli' for the suggestions. Now I will just have to reinstall Origin from the CDs when I am back home a month from now (did not bring them abroad), in order to be able to update to SR4 (due to false SR2 upgrade). I will then let you know the result.
I already submitted a data set as requested in the first answer to this post. |
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contour polar plot with r theta z z z z