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Re: [Gnuplot-info] Question on Plots on Non-regular Grid
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From: Lorenzo I. <lor...@gm...> - 2007-07-02 16:27:01
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Ops...I created the wrong example in which the data file are in actually on a rectangular grid. Lorenzo On 02/07/07, Lorenzo Isella <lor...@gm...> wrote: > Hello, > And thanks for your suggestion. > It seems there is a problem, though. > Somehow gnuplot does not understand that it is working on a cylinder > cross section. > If I try: > > set dgrid3d 10,10 > set hidden3d > set pm3d > splot "example.txt" u 1:2:3 with lines > > where "example.txt" is the file containing the data as shown in the > email, what I get is a rectangular grid. Is it simply an artifact due > to the low number of grid points or am I doing something wrong? > Many thanks > > Lorenzo > > > > > Message: 6 > > Date: Mon, 2 Jul 2007 07:02:09 -0700 (PDT) > > From: Thomas Sefzick <t.s...@fz...> > > Subject: Re: [Gnuplot-info] Question on Plots on Non-regular Grid > > To: gnu...@li... > > Message-ID: <113...@ta...> > > Content-Type: text/plain; charset=us-ascii > > > > > > a contour plot is not so easy unless you have your data on a grid. > > re-binning a few data points into a grid with 'dgrid3d' doesn't work. > > > > so, either you have a reasonable number of data points - so many, > > that 'set dgrid3d' works - or you do the re-binning (= filling a > > 2d-histogram) > > outside of gnuplot. > > or, for a very low number of data points, a 'poor man's' solution could be: > > > > set xrange [-1:1] > > set yrange [-1:1] > > set view map > > set mapping cyl > > splot 'datafile' using 1:3:2 with points pointtype 5 pointsize 3 palette > > > > > > Lorenzo Isella wrote: > > > > > > Dear All, > > > I am fairly new to data plotting and visualization. > > > My problem should be simple, but it is not straightforward to tackle in > > > R or Python. > > > On the cross section of a pipe (i.e. on a circle) I have a temperature > > > reading of the kind: T=T(r,theta). > > > I would like to make a 2D contour plot using colors such that one can see > > > that the domain where I am plotting is actually a circle. > > > Furthermore, I do not have necessarily an equally spaced grid. > > > For instance, let me consider the case of 5 theta's and 7 radial > > > position and consequently 35 values of T (just a simple test): > > > > > > theta > > > R T > > > 0.000000000000000000e+00 0.000000000000000000e+00 5.459815003314423620e+01 > > > 0.000000000000000000e+00 1.666666666666666574e-01 4.853828855239110851e+01 > > > 0.000000000000000000e+00 3.333333333333333148e-01 4.315101251901344881e+01 > > > 0.000000000000000000e+00 5.000000000000000000e-01 3.836167151642037965e+01 > > > 0.000000000000000000e+00 6.666666666666666297e-01 3.410390059527122020e+01 > > > 0.000000000000000000e+00 8.333333333333332593e-01 3.031870066752165016e+01 > > > 0.000000000000000000e+00 1.000000000000000000e+00 2.695362096775039973e+01 > > > 1.570796326794896558e+00 0.000000000000000000e+00 2.396203225329512776e+01 > > > 1.570796326794896558e+00 1.666666666666666574e-01 2.130248067207563523e+01 > > > 1.570796326794896558e+00 3.333333333333333148e-01 1.893811334477913277e+01 > > > 1.570796326794896558e+00 5.000000000000000000e-01 1.683616770181326316e+01 > > > 1.570796326794896558e+00 6.666666666666666297e-01 1.496751749887080329e+01 > > > 1.570796326794896558e+00 8.333333333333332593e-01 1.330626922033307302e+01 > > > 1.570796326794896558e+00 1.000000000000000000e+00 1.182940327795447999e+01 > > > 3.141592653589793116e+00 0.000000000000000000e+00 1.051645503298913731e+01 > > > 3.141592653589793116e+00 1.666666666666666574e-01 9.349231221746512333e+00 > > > 3.141592653589793116e+00 3.333333333333333148e-01 8.311557855141172624e+00 > > > 3.141592653589793116e+00 5.000000000000000000e-01 7.389056098930650407e+00 > > > 3.141592653589793116e+00 6.666666666666666297e-01 6.568943029058285532e+00 > > > 3.141592653589793116e+00 8.333333333333332593e-01 5.839854501207304871e+00 > > > 3.141592653589793116e+00 1.000000000000000000e+00 5.191687680104649871e+00 > > > 4.712388980384689674e+00 0.000000000000000000e+00 4.615461046534314882e+00 > > > 4.712388980384689674e+00 1.666666666666666574e-01 4.103189942205120566e+00 > > > 4.712388980384689674e+00 3.333333333333333148e-01 3.647775927922803252e+00 > > > 4.712388980384689674e+00 5.000000000000000000e-01 3.242908421924544982e+00 > > > 4.712388980384689674e+00 6.666666666666666297e-01 2.882977255397825012e+00 > > > 4.712388980384689674e+00 8.333333333333332593e-01 2.562994933482758420e+00 > > > 4.712388980384689674e+00 1.000000000000000000e+00 2.278527524544009530e+00 > > > 6.283185307179586232e+00 0.000000000000000000e+00 2.025633220058637107e+00 > > > 6.283185307179586232e+00 1.666666666666666574e-01 1.800807713756398032e+00 > > > 6.283185307179586232e+00 3.333333333333333148e-01 1.600935643142084031e+00 > > > 6.283185307179586232e+00 5.000000000000000000e-01 1.423247420534685892e+00 > > > 6.283185307179586232e+00 6.666666666666666297e-01 1.265280855439646635e+00 > > > 6.283185307179586232e+00 8.333333333333332593e-01 1.124847036463023642e+00 > > > 6.283185307179586232e+00 1.000000000000000000e+00 1.000000000000000000e+00 > > > > > > > > > > > > How would you plot them in order to have a 2D-color plot where one can > > > understand we are working on a circle (well, maybe it will look like > > > something different since I have only a few grid points, but the aim > > > is clear, I hope)? > > > Despite its simplicity, this has been taking me a long time and I am not > > > done yet. Someone has recently suggested to learn VTK, but it may be too > > > much for what I have in mind. > > > Anyone who can give me a simple script to read that data and get a > > > contour plot on a pipe's cross section would help me a lot (I am sure > > > it must amount to a few lines). > > > Kind Regards > > > > > > Lorenzo > > > > > > ------------------------------------------------------------------------- > > > This SF.net email is sponsored by DB2 Express > > > Download DB2 Express C - the FREE version of DB2 express and take > > > control of your XML. No limits. Just data. Click to get it now. > > > http://sourceforge.net/powerbar/db2/ > > > _______________________________________________ > > > Gnuplot-info mailing list > > > Gnu...@li... > > > https://lists.sourceforge.net/lists/listinfo/gnuplot-info > > > > > > > > > > -- > > View this message in context: http://www.nabble.com/Question-on-Plots-on-Non-regular-Grid-tf4009454.html#a11394474 > > Sent from the Gnuplot - User mailing list archive at Nabble.com. > > > > > > > > > > ------------------------------ > > > > ------------------------------------------------------------------------- > > This SF.net email is sponsored by DB2 Express > > Download DB2 Express C - the FREE version of DB2 express and take > > control of your XML. No limits. Just data. Click to get it now. > > http://sourceforge.net/powerbar/db2/ > > > > ------------------------------ > > > > _______________________________________________ > > Gnuplot-info mailing list > > Gnu...@li... > > https://lists.sourceforge.net/lists/listinfo/gnuplot-info > > > > > > End of Gnuplot-info Digest, Vol 14, Issue 1 > > ******************************************* > > > |
