Re: [Matplotlib-users] line,

[Eric F. <ef...@ha...>]

On 06/15/2011 12:53 PM, jonasr wrote:
>
> Thank you for the fast reply, according to you line and "line," shouldt make
> a difference in this case,

No, that's not what I said.  Using "line" gives you a list with one 
element, but using "line," gives you the element itself, not the list.

> i tried the code with line and line,  and it only works with line, ?
>
> so you say if i use
> a=[1,2,3]
> then b, = a should be 1 ?  i just get the error message to many values to
> unpack ...

Yes, when you use this automatic unpacking the number of items has to 
match.  You can only use

a, b = rhs

when you *know* rhs will be a sequence with two, and only two, elements.

Eric

>
>
>
> efiring wrote:
>>
>> On 06/15/2011 12:35 PM, jonasr wrote:
>>>
>>> hello,
>>>
>>> a lot of matplotlib examples i saw included the usage of line, i.e.
>>>
>>> from pylab import *
>>> import time
>>>
>>> ion()
>>>
>>> tstart = time.time()               # for profiling
>>> x = arange(0,2*pi,0.01)            # x-array
>>> line, = plot(x,sin(x))
>>> for i in arange(1,200):
>>>       line.set_ydata(sin(x+i/10.0))  # update the data
>>>       draw()                         # redraw the canvas
>>>
>>> print 'FPS:' , 200/(time.time()-tstart)
>>>
>>> can anybody explain to me whats the difference between line and line, ?
>>>
>>
>> plot returns a list of lines, and
>>
>> line, = plot(...)
>>
>> returns the first one (which in your case is the only one)
>>
>> It is the same as
>>
>> line = plot(...)[0]
>>
>> It is a special case of Python's sequence unpacking, e.g.:
>>
>> a, b, c = [1, 2, 3]
>>
>> Eric
>>
>> ------------------------------------------------------------------------------
>> EditLive Enterprise is the world's most technically advanced content
>> authoring tool. Experience the power of Track Changes, Inline Image
>> Editing and ensure content is compliant with Accessibility Checking.
>> http://p.sf.net/sfu/ephox-dev2dev
>> _______________________________________________
>> Matplotlib-users mailing list
>> Mat...@li...
>> https://lists.sourceforge.net/lists/listinfo/matplotlib-users
>>
>>
>