Thread: [Matplotlib-users] How to do accumulation plots with matplotlib

Hi, I am a new user to matplotlib. I have a huge list of values that look
like this:

[1,0,0,0,2,3,2,1,0,0,0,2,2,1,3,0,0,3...]

each point basically represents the derivative of the line at that point, if
that makes any sense. I want to take this data and display it in a linegraph
as if it were this data:

[1,1,1,1,3,5,7,8,8,8,10,12,13,16,16,16,19,...]

...so the line grows as the numbers get bigger. Is there a plot that takes
data in the form of my first list, or is my only option to create a forloop
and construct the second list manually and just use that?

It seems the target audience for matplotlib is scientific people who know a
lot about math and statistics, which I am not. A lot of the documentation
just goes over my head.
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nbv4 <cp3...@oh...> writes:

> [1,0,0,0,2,3,2,1,0,0,0,2,2,1,3,0,0,3...]
>
> [...] I want to take this data and display it in a linegraph
> as if it were this data:
>
> [1,1,1,1,3,5,7,8,8,8,10,12,13,16,16,16,19,...]

You can use numpy.cumsum to transform your data. For example, in ipython
-pylab:

In [4]: x = [1,0,0,0,2,3,2,1,0,0,0,2,2,1,3,0,0,3]

In [5]: cumsum(x)
Out[5]: 
array([ 1,  1,  1,  1,  3,  6,  8,  9,  9,  9,  9, 11, 13, 14, 17, 17, 17,
       20])

In [6]: plot(cumsum(x))
Out[6]: [<matplotlib.lines.Line2D object at 0xa945070>]

-- 
Jouni K. Seppänen
http://www.iki.fi/jks

Jouni K. Seppänen wrote:
> 
> nbv4 <cp3...@oh...> writes:
> 
>> [1,0,0,0,2,3,2,1,0,0,0,2,2,1,3,0,0,3...]
>>
>> [...] I want to take this data and display it in a linegraph
>> as if it were this data:
>>
>> [1,1,1,1,3,5,7,8,8,8,10,12,13,16,16,16,19,...]
> 
> You can use numpy.cumsum to transform your data. For example, in ipython
> -pylab:
> 
> In [4]: x = [1,0,0,0,2,3,2,1,0,0,0,2,2,1,3,0,0,3]
> 
> In [5]: cumsum(x)
> Out[5]: 
> array([ 1,  1,  1,  1,  3,  6,  8,  9,  9,  9,  9, 11, 13, 14, 17, 17, 17,
>        20])
> 
> In [6]: plot(cumsum(x))
> Out[6]: [<matplotlib.lines.Line2D object at 0xa945070>]
> 
> -- 
> Jouni K. Seppänen
> http://www.iki.fi/jks
> 
> 
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> 
Thats exactly it, thanks!
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