"Thanks for this also Ben --- I will quite likely get this book. However,
considering the complexity of Matplotlib --- only 174 pages bothers me a
little. :-)"
I am just that good! No, really though, the book focuses only on a subset
of features in Matplotlib, and it does assume that you are somewhat
comfortable with the language (or at least, understand the basics of Object
Oriented Programming and terminology). There will be another book that will
come out in a few months that is intended to be a complete refresh of
Sandro Toshi's 2009 book that might be more up your alley, but I don't know
how much it will cover of Animations. Sandro's book was released before the
animation module was even a twinkle in Ryan May's eye...
Cheers!
Ben Root
On Thu, Apr 23, 2015 at 1:40 PM, Virgil Stokes <v...@it.uu.se> wrote:
> On 23-Apr-2015 18:48, Benjamin Root wrote:
>
> ... keeping conversation on-list ...
>
> The reason why you get that error is because you took out the argument
> from the call signature. But, FuncAnimation assumes that it can send in at
> least one argument. That argument is not optional, even if you aren't using
> it. So, animate() was called with an argument by FuncAnimation internally,
> but since animate() as defined by you did not have that argument, it fails.
>
> Ok --- thanks again for the clarification. Who knows, with a little help
> from this list, I might someday be able to create some useful animations
> with Matplotlib ;-)
>
>
> Cheers!
> Ben Root
>
>
> On Thu, Apr 23, 2015 at 12:32 PM, Virgil Stokes <v...@it.uu.se> wrote:
>
>> On 23-Apr-2015 18:25, Benjamin Root wrote:
>>
>> The documentation should say "the number", not "a number". This
>> particular argument expects either a generator, an iterable, or an integer.
>> If none is given, it will try and figure out something for itself. The
>> integer is used to create a number generator, and so you effectively have
>> an iterable that supplies the first argument to the animation function.
>>
>> Ok Benjamin :-) --- thanks for the clarification.
>>
>>
>> Often times, the first argument to this function is just a frame index.
>> It is quite possible that you don't need it at all, but it is a part of the
>> defined API that the FuncAnimation assumes to be able to call the
>> user-supplied function.
>>
>> Does that help?
>>
>> Yes, this does indeed help. But I am still puzzled by the error message
>> given when I remove the argument to the animate function.
>>
>>
>> Ben Root
>>
>> <shameless_plug>
>> P.S. - My new book "Interactive Applications using Matplotlib" has an
>> entire chapter devoted to animations
>> </shameless_plug>
>>
>> Thanks for this also Ben --- I will quite likely get this book.
> However, considering the complexity of Matplotlib --- only 174 pages
> bothers me a little. :-)
>
>
>>
>> On Thu, Apr 23, 2015 at 12:05 PM, Virgil Stokes <v...@it.uu.se> wrote:
>>
>>> Thanks for your reply to my post, Jerzy.
>>>
>>> On 23-Apr-2015 13:18, Jerzy Karczmarczuk wrote:
>>>
>>>
>>>
>>> Le 23/04/2015 12:22, Virgil Stokes a écrit :
>>>
>>> The following interesting example (random_data.py) is posted at:
>>>
>>> http://matplotlib.org/1.4.2/examples/animation/random_data.html
>>>
>>>
>>> import matplotlib.pyplot as plt
>>> import matplotlib.animation as animation
>>>
>>> import numpy as np
>>>
>>> Yes, I forgot to include this
>>>
>>>
>>> fig, ax = plt.subplots()
>>> line, = ax.plot(np.random.rand(10))
>>> ax.set_ylim(0, 1)
>>>
>>> def update(data):
>>> line.set_ydata(data)
>>> return line,
>>>
>>> def data_gen():
>>> while True: yield np.random.rand(10)
>>>
>>> ani = animation.FuncAnimation(fig, update, data_gen, interval=100)
>>> plt.show()
>>>
>>> This codes works; but, I am very confused by it. For example:
>>>
>>> 1. There are 3 positional arguments given for animation.FuncAnimation;
>>> but, in the
>>> API documentation for this class (
>>> <http://matplotlib.org/api/animation_api.html>
>>> http://matplotlib.org/api/animation_api.html), only
>>> two positional arguments are shown.
>>>
>>> The third one is the third one,
>>> "*frames* can be a generator, an iterable, or a number of frames."
>>>
>>> This makes very little sense to me --- what does "or a number of
>>> frames" mean?
>>>
>>> The name "data_gen" could suggest its meaning (after having read the
>>> doc).
>>>
>>> I am not sure what you are referencing as "the doc"; but I did read the
>>> documentation several times and English is my native language.
>>>
>>> Note please that the keyword parameters are specified extra.
>>>
>>> I am aware of this. Perhaps, I am a Python dummy --- when I see
>>> something like value = None in a Python API argument, I interpret this as a
>>> keyword argument and not a generator.
>>>
>>>
>>> 2. data, the argument to the update function seems to be undefined.
>>>
>>> FuncAnimation usually passes the frame number: 0, 1, 2, ... as the first
>>> parameter of the update function, when "frames" is None, or the number of
>>> frames. If - as here - the third parameter is a generator, it passes the
>>> yielded data to update.
>>> It may be used or not.
>>>
>>> Ok, I understand that better now. But, you say "or *the number* of
>>> frames" but the documentation reads "or *a number* of frames" --- what
>>> does this mean?
>>>
>>> And I still do not understand how to use the first argument of the
>>> function to be called for the animation. In another animation example (
>>> histogram.py), the animation function is defined by:
>>>
>>> def animate(i):
>>> # simulate new data coming in
>>> data = np.random.randn(1000
>>> n, bins = np.histogram(data, 100)
>>> top = bottom + n
>>> verts[1::5,1] = top
>>> verts[2::5,1] = top
>>>
>>> This works of course; but, why is the "i" required? There is no other
>>> reference to it in the entire script. If I remove it; i.e. use def
>>> animate(): I get the following error:
>>>
>>> TypeError: animate() takes no arguments (1 given)
>>>
>>> I do not understand how this explains the fact that the function no
>>> longer has any arguments. Please explain the meaning of this error message?
>>>
>>>
>>> Please, in such cases test your programs by adding some simple tracing
>>> contraptions, say, print(data) inside update.
>>>
>>> I did this and more before posting my email. I would not have posted
>>> this unless I thought it was necessary. And I thought one purpose of this
>>> user group was to help people --- even if they ask a question which may be
>>> annoying or "stupid" in some subscribers opinion. I try to remember what a
>>> very wise teacher once said --- "there is no such thing as a stupid
>>> question".
>>>
>>>
>>> ------------------------------------------------------------------------------
>>> BPM Camp - Free Virtual Workshop May 6th at 10am PDT/1PM EDT
>>> Develop your own process in accordance with the BPMN 2 standard
>>> Learn Process modeling best practices with Bonita BPM through live
>>> exercises
>>> http://www.bonitasoft.com/be-part-of-it/events/bpm-camp-virtual-
>>> event?utm_
>>> source=Sourceforge_BPM_Camp_5_6_15&utm_medium=email&utm_campaign=VA_SF
>>> _______________________________________________
>>> Matplotlib-users mailing list
>>> Matplotlib-users@lists.sourceforge.net
>>> https://lists.sourceforge.net/lists/listinfo/matplotlib-users
>>>
>>>
>>
>>
>
>
------------------------------------------------------------------------------
BPM Camp - Free Virtual Workshop May 6th at 10am PDT/1PM EDT
Develop your own process in accordance with the BPMN 2 standard
Learn Process modeling best practices with Bonita BPM through live exercises
http://www.bonitasoft.com/be-part-of-it/events/bpm-camp-virtual- event?utm_
source=Sourceforge_BPM_Camp_5_6_15&utm_medium=email&utm_campaign=VA_SF
_______________________________________________
Matplotlib-users mailing list
Matplotlib-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/matplotlib-users
