[Matplotlib-users] cartesian/polar problem
I have a small problem which I suspect can be solved in an easy and elegant way, and it is simply lack of sleep/stupidity preventing me from finding it. I have a number of line drawings comprised of cartesian points. I need to project them onto a sphere (they are drawings of constellations, so I need to project them onto an imaginary celestial sphere) and convert the points into sphercal co-ordinates. I *can* map the points to a sphere, that's no problem. But obviously, when I do this they become distorted. What I want to do is find out what the points should be to get an undistorted view - i.e the mapping that will produce a projection so the points match the cartesian version. Obviously, I realise this depends on the projection used etc, but basically, a small amount of distortion is fine. I am sure there must be a simple way to achieve this, but I can't seem to manage it. --- Nick Veitch -- Simplify data backup and recovery for your virtual environment with vRanger. Installation's a snap, and flexible recovery options mean your data is safe, secure and there when you need it. Discover what all the cheering's about. Get your free trial download today. http://p.sf.net/sfu/quest-dev2dev2 ___ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
Re: [Matplotlib-users] Not able to access CSV file:
Hi,
have you tried the examples that I have provided a couple days ago,
see below? I cannot see why it should not work. These are the absolute
basics that you need to understand.
Btw, there is no need to use csv2rec unless you want/need column or row headers.
Here's a full script that does what you want. Now, please take the
time and work through the example that I have provided. In case you
need further help, please don't start a new thread but reply to this
one.
Best regards,
Daniel
# -*- coding: utf-8 -*-
import matplotlib.pyplot as plt
import pylab
import scipy
datafile1 = 'ch1_s1_lrr.csv'
datafile2 = 'ch1_s1_baf.csv'
## create dummy data
data = pylab.rand(1,12)
pylab.savetxt(datafile1, data, delimiter=';')
pylab.savetxt(datafile2, data, delimiter=';')
## load data and transpose
a1 = pylab.loadtxt(datafile1, comments='#', delimiter=';').T
print 'loading', datafile1
b1 = pylab.loadtxt(datafile2, comments='#', delimiter=';').T
print 'loading', datafile2
## axis limits
#v1 = [0,98760,0,1]
#v2 = [0,98760,-2,2]
v1 = [0,1]
v2 = [-2,2]
plt.close('all')
plt.figure()
plt.subplot(2,1,1)
#plt.axis(v2)
plt.ylim(v2)
#plt.plot(a1, 'r.')
for i in range(6):
plt.plot(a1[i])
plt.subplot(2,1,2)
#plt.axis(v1)
plt.ylim(v1)
#plt.plot(b1, 'b.')
## need masked arrays here
## http://physics.nmt.edu/~raymond/software/python_notes/paper003.html
m = b1 >= 0.05
b1masked = scipy.ma.array(b1,mask=m)
## print first two cols
print b1masked[0:2]
for i in range(6,12):
plt.plot(b1masked[i])
plt.show()
2011/6/3 Karthikraja Velmurugan :
> import matplotlib.pyplot as plt
> import pylab
> datafile1 = 'ch1_s1_lrr.csv'
> datafile2 = 'ch1_s1_baf.csv'
>
> a1 = pylab.loadtxt(datafile1, comments='#', delimiter=';')
> b1 = pylab.loadtxt(datafile2, comments='#', delimiter=';')
>
> v1 = [0,98760,0,1]
> v2 = [0,98760,-2,2]
>
> plt.figure(1)
>
> plt.subplot(2,1,1)
> print 'loading', datafile1
> plt.axis(v2)
> plt.plot(a1, 'r.')
>
> plt.subplot(2,1,2)
> print 'loading', datafile2
> plt.axis(v1)
> plt.plot(b1, 'b.')
>
> plt.show()
2011/5/30 Daniel Mader :
> Hi,
>
> the content of the CSV is stored as an array after reading. You can
> simply access rows and columns like in Matlab:
>
> firstrow = a1[0]
> firstcol = a1.T[0]
>
> The .T transposes the array.
>
> The second element of the third row would be
>
> elem32 = a1[2][1]
> which is equivalent to
> elem32 = a1[2,1]
>
> A range of e.g. rows 3 to 6 is
> range36 = a1[2:6]
>
> Please have a look here for getting started with scipy/numpy:
> http://pages.physics.cornell.edu/~myers/teaching/ComputationalMethods/python/arrays.html
> and
> http://www.scipy.org/NumPy_for_Matlab_Users
>
> Hope this helps,
> Daniel
>
> 2011/5/27 Karthikraja Velmurugan :
>> Hello Daniel,
>>
>> The code you have given is simple and works fab. Thank you very much. But I
>> wasn't able to find an example which accesses the columns of a CSV files
>> when I import data through "datafile="filename.csv"" option. It will be
>> great if you could help with accessing individual columns. What excatly I am
>> looking for is to access individual coulmns (of the same CSV file), do
>> calculations using the two coumns and plot them into seperate subplots of
>> the same graph.
>> I modified the script a lil bit. Please find it below:
>>
>> import matplotlib.pyplot as plt
>> import pylab
>> datafile1 = 'ch1_s1_lrr.csv'
>> datafile2 = 'ch1_s1_baf.csv'
>> a1 = pylab.loadtxt(datafile1, comments='#', delimiter=';')
>> b1 = pylab.loadtxt(datafile2, comments='#', delimiter=';')
>> v1 = [0,98760,0,1]
>> v2 = [0,98760,-2,2]
>> plt.figure(1)
>> plt.subplot(4,1,1)
>> print 'loading', datafile1
>> plt.axis(v2)
>> plt.plot(a1, 'r.')
>> plt.subplot(4,1,2)
>> print 'loading', datafile2
>> plt.axis(v1)
>> plt.plot(b1, 'b.')
>> plt.show()
>>
>> Thank you very much in advance for your time and suggestions.
>>
>> Karthik
--
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[Matplotlib-users] Plotting in loop problem, not refreshing
Hi everyone , I know this has been posted several times now, But I could not understand qietly why my simple code does not work. here is the code: http://old.nabble.com/file/p31775254/LinearConvection.py LinearConvection.py The problem in detail: In the solver loop ( the outer loop) , The plot should be updated after every time step, but it stays the same. I'm a complete noob in python, so excuse my simple communicating language. thanks alot, Armin -- View this message in context: http://old.nabble.com/Plotting-in-loop-problem%2C-not-refreshing-tp31775254p31775254.html Sent from the matplotlib - users mailing list archive at Nabble.com. -- Simplify data backup and recovery for your virtual environment with vRanger. Installation's a snap, and flexible recovery options mean your data is safe, secure and there when you need it. Discover what all the cheering's about. Get your free trial download today. http://p.sf.net/sfu/quest-dev2dev2 ___ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
Re: [Matplotlib-users] Plotting in loop problem, not refreshing
Your code should work (and does on my system)... What backend, version of matplotlib, OS, etc are you running? On Sat, Jun 4, 2011 at 4:54 PM, Armin G wrote: > > Hi everyone , > > I know this has been posted several times now, But I could not understand > qietly why my simple code does not work. > here is the code: > http://old.nabble.com/file/p31775254/LinearConvection.pyLinearConvection.py > > The problem in detail: In the solver loop ( the outer loop) , The plot > should be updated after every time step, but it stays the same. > > I'm a complete noob in python, so excuse my simple communicating language. > > thanks alot, > Armin > -- > View this message in context: > http://old.nabble.com/Plotting-in-loop-problem%2C-not-refreshing-tp31775254p31775254.html > Sent from the matplotlib - users mailing list archive at Nabble.com. > > > > -- > Simplify data backup and recovery for your virtual environment with > vRanger. > Installation's a snap, and flexible recovery options mean your data is > safe, > secure and there when you need it. Discover what all the cheering's about. > Get your free trial download today. > http://p.sf.net/sfu/quest-dev2dev2 > ___ > Matplotlib-users mailing list > Matplotlib-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/matplotlib-users > -- Simplify data backup and recovery for your virtual environment with vRanger. Installation's a snap, and flexible recovery options mean your data is safe, secure and there when you need it. Discover what all the cheering's about. Get your free trial download today. http://p.sf.net/sfu/quest-dev2dev2 ___ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
Re: [Matplotlib-users] Exact semantics of ion()??
https://github.com/efiring/matplotlib/blob/faq_show_draw/doc/faq/usage_faq.rst Eric, Ben, See if the section "What is interactive mode" makes sense to you. I have just added it to a feature branch (which includes some other faq madifications, mainly moving the backend section from installation to usage), but have not yet generated a pull request. It doesn't go into every detail, or into the underlying machinery. It is intended to provide just enough understanding to clear up user-level confusion about interactive mode, show, and draw, and let most relatively new users get on with their work. Eric -- Simplify data backup and recovery for your virtual environment with vRanger. Installation's a snap, and flexible recovery options mean your data is safe, secure and there when you need it. Discover what all the cheering's about. Get your free trial download today. http://p.sf.net/sfu/quest-dev2dev2 ___ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
