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From: Lorenzo I. <lor...@gm...> - 2007-06-25 17:03:41
|
Dear All, I am quite a newbie about Python and Pylab, but I am starting to like the ease you can develop with using these tools. I am interested in 2D radial plots (think for instance about the plot of the temperature along the cross-section of a pipe). I had a look at the tutorial online, in particular to the case described in: http://matplotlib.sourceforge.net/screenshots/polar_demo.py but there is something which is not 100% clear to me. What if, instead of having an analytical expression for the quantity I want to plot I have to read it (together with the r and theta coordinates) from a file, e.g.: r theta T where the columns r and theta contain the list of (r,theta) coordinates (the "grid" I am using along the cross section) and T the temperature evaluated at that grid point? If necessary, I can post an example file (but at the moment I am working with fairly big files and I think I conveyed an idea of what I am after). Many thanks Lorenzo |
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From: Benoit D. <ben...@uc...> - 2007-06-26 06:17:20
|
Hey,
That's quite simple. Assume your file containing the data is name =20
Data.dat and is in the same directory than your python script.
from pylab import *
from numpy import *
tab =3D load('Data.dat') #load the file
r =3D tab[:,0] #get the r coordinates
theta =3D tab[:,1] #get the theta coordinates
T =3D tab[:,2] #get the temperature
# now, you can process/plot your data
Hope this help.
Best regards.
Benoit
Le 25-juin-07 =E0 19:03, Lorenzo Isella a =E9crit :
> Dear All,
> I am quite a newbie about Python and Pylab, but I am starting to like
> the ease you can develop with using these tools.
> I am interested in 2D radial plots (think for instance about the plot
> of the temperature along the cross-section of a pipe).
> I had a look at the tutorial online, in particular to the case =20
> described in:
>
> http://matplotlib.sourceforge.net/screenshots/polar_demo.py
>
> but there is something which is not 100% clear to me.
> What if, instead of having an analytical expression for the quantity I
> want to plot I have to read it (together with the r and theta
> coordinates) from a file, e.g.:
>
> r theta T
>
>
> where the columns r and theta contain the list of (r,theta)
> coordinates (the "grid" I am using along the cross section) and T the
> temperature evaluated at that grid point?
> If necessary, I can post an example file (but at the moment I am
> working with fairly big files and I think I conveyed an idea of what I
> am after).
> Many thanks
>
> Lorenzo
>
> ----------------------------------------------------------------------=20=
> ---
> 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/
> _______________________________________________
> Matplotlib-users mailing list
> Mat...@li...
> https://lists.sourceforge.net/lists/listinfo/matplotlib-users
--
Dr. Benoit Donnet
Universit=E9 Catholique de Louvain (UCL)
Facult=E9 des Sciences Appliqu=E9es - D=E9partement d'Ing=E9nierie =20
Informatique (INGI)
Place Sainte Barbe, 2
1348 Louvain-la-Neuve
Belgium
Phone: +32 10 47 87 18
Home page: http://inl.info.ucl.ac.be/donnet
|
|
From: Lorenzo I. <lor...@gm...> - 2007-06-26 13:36:35
Attachments:
example.txt
|
Hello,
Thanks for your suggestion, but I still have a problem.
Maybe I did not make myself clear (or most likely I have a problem
about how to implement your suggestion): actually I have T=3DT(r,theta)
and I would like to make a 2D plot using colors such that one can see
that the domain where I am plotting is actually a circle.
The example I mentioned is not exactly what I need since there one can
find how to plot in polar coordinates a function of r alone.
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 consequentely 35 values of T:
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)?
Kind Regards
Lorenzo
On 26/06/07, Benoit Donnet <ben...@uc...> wrote:
> Hey,
>
> That's quite simple. Assume your file containing the data is name
> Data.dat and is in the same directory than your python script.
>
> from pylab import *
> from numpy import *
>
> tab =3D load('Data.dat') #load the file
> r =3D tab[:,0] #get the r coordinates
> theta =3D tab[:,1] #get the theta coordinates
> T =3D tab[:,2] #get the temperature
>
> # now, you can process/plot your data
>
> Hope this help.
>
> Best regards.
>
> Benoit
>
>
> Le 25-juin-07 =E0 19:03, Lorenzo Isella a =E9crit :
>
> > Dear All,
> > I am quite a newbie about Python and Pylab, but I am starting to like
> > the ease you can develop with using these tools.
> > I am interested in 2D radial plots (think for instance about the plot
> > of the temperature along the cross-section of a pipe).
> > I had a look at the tutorial online, in particular to the case
> > described in:
> >
> > http://matplotlib.sourceforge.net/screenshots/polar_demo.py
> >
> > but there is something which is not 100% clear to me.
> > What if, instead of having an analytical expression for the quantity I
> > want to plot I have to read it (together with the r and theta
> > coordinates) from a file, e.g.:
> >
> > r theta T
> >
> >
> > where the columns r and theta contain the list of (r,theta)
> > coordinates (the "grid" I am using along the cross section) and T the
> > temperature evaluated at that grid point?
> > If necessary, I can post an example file (but at the moment I am
> > working with fairly big files and I think I conveyed an idea of what I
> > am after).
> > Many thanks
> >
> > 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/
> > _______________________________________________
> > Matplotlib-users mailing list
> > Mat...@li...
> > https://lists.sourceforge.net/lists/listinfo/matplotlib-users
>
> --
> Dr. Benoit Donnet
> Universit=E9 Catholique de Louvain (UCL)
> Facult=E9 des Sciences Appliqu=E9es - D=E9partement d'Ing=E9nierie
> Informatique (INGI)
> Place Sainte Barbe, 2
> 1348 Louvain-la-Neuve
> Belgium
> Phone: +32 10 47 87 18
> Home page: http://inl.info.ucl.ac.be/donnet
>
>
>
>
|
|
From: Brian <fo...@gm...> - 2007-06-26 15:14:38
|
It sounds to me that you want to have a contour plot which takes as input
the r,theta, and T. I would suggest just
On 6/26/07, Lorenzo Isella <lor...@gm...> wrote:
>
> Hello,
> Thanks for your suggestion, but I still have a problem.
> Maybe I did not make myself clear (or most likely I have a problem
> about how to implement your suggestion): actually I have T=3DT(r,theta)
> and I would like to make a 2D plot using colors such that one can see
> that the domain where I am plotting is actually a circle.
> The example I mentioned is not exactly what I need since there one can
> find how to plot in polar coordinates a function of r alone.
> 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 consequentely 35 values of T:
>
> theta R
> T
> 0.000000000000000000e+00 0.000000000000000000e+00 5.459815003314423620e+0=
1
> 0.000000000000000000e+00 1.666666666666666574e-01 4.853828855239110851e+0=
1
> 0.000000000000000000e+00 3.333333333333333148e-01 4.315101251901344881e+0=
1
> 0.000000000000000000e+00 5.000000000000000000e-01 3.836167151642037965e+0=
1
> 0.000000000000000000e+00 6.666666666666666297e-01 3.410390059527122020e+0=
1
> 0.000000000000000000e+00 8.333333333333332593e-01 3.031870066752165016e+0=
1
> 0.000000000000000000e+00 1.000000000000000000e+00 2.695362096775039973e+0=
1
> 1.570796326794896558e+00 0.000000000000000000e+00 2.396203225329512776e+0=
1
> 1.570796326794896558e+00 1.666666666666666574e-01 2.130248067207563523e+0=
1
> 1.570796326794896558e+00 3.333333333333333148e-01 1.893811334477913277e+0=
1
> 1.570796326794896558e+00 5.000000000000000000e-01 1.683616770181326316e+0=
1
> 1.570796326794896558e+00 6.666666666666666297e-01 1.496751749887080329e+0=
1
> 1.570796326794896558e+00 8.333333333333332593e-01 1.330626922033307302e+0=
1
> 1.570796326794896558e+00 1.000000000000000000e+00 1.182940327795447999e+0=
1
> 3.141592653589793116e+00 0.000000000000000000e+00 1.051645503298913731e+0=
1
> 3.141592653589793116e+00 1.666666666666666574e-01 9.349231221746512333e+0=
0
> 3.141592653589793116e+00 3.333333333333333148e-01 8.311557855141172624e+0=
0
> 3.141592653589793116e+00 5.000000000000000000e-01 7.389056098930650407e+0=
0
> 3.141592653589793116e+00 6.666666666666666297e-01 6.568943029058285532e+0=
0
> 3.141592653589793116e+00 8.333333333333332593e-01 5.839854501207304871e+0=
0
> 3.141592653589793116e+00 1.000000000000000000e+00 5.191687680104649871e+0=
0
> 4.712388980384689674e+00 0.000000000000000000e+00 4.615461046534314882e+0=
0
> 4.712388980384689674e+00 1.666666666666666574e-01 4.103189942205120566e+0=
0
> 4.712388980384689674e+00 3.333333333333333148e-01 3.647775927922803252e+0=
0
> 4.712388980384689674e+00 5.000000000000000000e-01 3.242908421924544982e+0=
0
> 4.712388980384689674e+00 6.666666666666666297e-01 2.882977255397825012e+0=
0
> 4.712388980384689674e+00 8.333333333333332593e-01 2.562994933482758420e+0=
0
> 4.712388980384689674e+00 1.000000000000000000e+00 2.278527524544009530e+0=
0
> 6.283185307179586232e+00 0.000000000000000000e+00 2.025633220058637107e+0=
0
> 6.283185307179586232e+00 1.666666666666666574e-01 1.800807713756398032e+0=
0
> 6.283185307179586232e+00 3.333333333333333148e-01 1.600935643142084031e+0=
0
> 6.283185307179586232e+00 5.000000000000000000e-01 1.423247420534685892e+0=
0
> 6.283185307179586232e+00 6.666666666666666297e-01 1.265280855439646635e+0=
0
> 6.283185307179586232e+00 8.333333333333332593e-01 1.124847036463023642e+0=
0
> 6.283185307179586232e+00 1.000000000000000000e+00 1.000000000000000000e+0=
0
>
>
>
> 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)?
> Kind Regards
>
> Lorenzo
>
>
>
>
>
> On 26/06/07, Benoit Donnet <ben...@uc...> wrote:
> > Hey,
> >
> > That's quite simple. Assume your file containing the data is name
> > Data.dat and is in the same directory than your python script.
> >
> > from pylab import *
> > from numpy import *
> >
> > tab =3D load('Data.dat') #load the file
> > r =3D tab[:,0] #get the r coordinates
> > theta =3D tab[:,1] #get the theta coordinates
> > T =3D tab[:,2] #get the temperature
> >
> > # now, you can process/plot your data
> >
> > Hope this help.
> >
> > Best regards.
> >
> > Benoit
> >
> >
> > Le 25-juin-07 =E0 19:03, Lorenzo Isella a =E9crit :
> >
> > > Dear All,
> > > I am quite a newbie about Python and Pylab, but I am starting to like
> > > the ease you can develop with using these tools.
> > > I am interested in 2D radial plots (think for instance about the plot
> > > of the temperature along the cross-section of a pipe).
> > > I had a look at the tutorial online, in particular to the case
> > > described in:
> > >
> > > http://matplotlib.sourceforge.net/screenshots/polar_demo.py
> > >
> > > but there is something which is not 100% clear to me.
> > > What if, instead of having an analytical expression for the quantity =
I
> > > want to plot I have to read it (together with the r and theta
> > > coordinates) from a file, e.g.:
> > >
> > > r theta T
> > >
> > >
> > > where the columns r and theta contain the list of (r,theta)
> > > coordinates (the "grid" I am using along the cross section) and T the
> > > temperature evaluated at that grid point?
> > > If necessary, I can post an example file (but at the moment I am
> > > working with fairly big files and I think I conveyed an idea of what =
I
> > > am after).
> > > Many thanks
> > >
> > > 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/
> > > _______________________________________________
> > > Matplotlib-users mailing list
> > > Mat...@li...
> > > https://lists.sourceforge.net/lists/listinfo/matplotlib-users
> >
> > --
> > Dr. Benoit Donnet
> > Universit=E9 Catholique de Louvain (UCL)
> > Facult=E9 des Sciences Appliqu=E9es - D=E9partement d'Ing=E9nierie
> > Informatique (INGI)
> > Place Sainte Barbe, 2
> > 1348 Louvain-la-Neuve
> > Belgium
> > Phone: +32 10 47 87 18
> > Home page: http://inl.info.ucl.ac.be/donnet
> >
> >
> >
> >
>
> -------------------------------------------------------------------------
> 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/
> _______________________________________________
> Matplotlib-users mailing list
> Mat...@li...
> https://lists.sourceforge.net/lists/listinfo/matplotlib-users
>
>
>
|
|
From: Lorenzo I. <lor...@gm...> - 2007-06-26 15:42:36
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Hello, Sorry for this tread getting quite long, but I am not getting there yet. Online I found examples like: #! /usr/bin/env python from pylab import * x=arange(-2,2,0.1) y=arange(-2,2,0.05) X,Y=meshgrid(x,y) z=exp(-(X*X + Y*Y)) + 0.6*exp(-((X+1.8)**2 + Y**2)) #contour(x,y,z,arange(0,1,0.1)) imshow(z,interpolation='nearest') show() and both the imshow() and contour() commands do nicely their job, but the scalar z is defined on a trivial rectangular domain and represented as a 2D array. In my problem I have: 1) a set of couples (theta,r) specifying a list of positions on a tube cross-section. 2) for each (theta,r) couple, I have a single value of T (which is thus a long 1D array). In general, (theta,r) may be two coordinates given on a non-trivial domain and I have a scalar specified for each couple I thus form. Both contour and imshow complain because they expect a 2D array. I am sorry if I am struggling over some triviality, but I am not making much progress by myself. Many thanks Lorenzo On 26/06/07, Brian <fo...@gm...> wrote: > It sounds to me that you want to have a contour plot which takes as input > the r,theta, and T. I would suggest just > > > On 6/26/07, Lorenzo Isella < lor...@gm...> wrote: > > > > Hello, > > Thanks for your suggestion, but I still have a problem. > > Maybe I did not make myself clear (or most likely I have a problem > > about how to implement your suggestion): actually I have T=T(r,theta) > > and I would like to make a 2D plot using colors such that one can see > > that the domain where I am plotting is actually a circle. > > The example I mentioned is not exactly what I need since there one can > > find how to plot in polar coordinates a function of r alone. > > 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 consequentely 35 values of T: > > > > 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)? > > Kind Regards > > > > Lorenzo |
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From: Andrew S. <str...@as...> - 2007-06-26 18:12:18
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Can you convert your radial coordinates to Cartesian coordinates and use approach #2 here: http://scipy.org/Cookbook/Matplotlib/Gridding_irregularly_spaced_data Lorenzo Isella wrote: > Hello, > Sorry for this tread getting quite long, but I am not getting there yet. > Online I found examples like: > > |
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