Filtering plots

_Armando_Serrano_Lom · July 18, 2007, 8:48am

Hello, I have a question.

Let’s say I have the following data:
[1,3,6,1,2,0,0,0,0,1,4,7,9,4,2,4,6,0,0,0,0,0,0,0,0,0,0,0,0,1,3,5,6,7,8]
which I want to plot, but I want to omit the zeros, so I would like to do something like:

plot(range(1,6), [1,3,6,1,2], ‘b’)
plot(range(10,18), [1,4,7,9,4,2,4,6], ‘b’)
plot(range(30,36), [1,3,5,6,7,8], ‘b’)
savefig(‘filtered.eps’)

Is there an elegant way of doing this?

Armando.

_Angel_Lopez · July 18, 2007, 9:18am

Hola Alejandro,

sure, I think this can do the job:

write a function to calc your X values:

def x(data):
    X=
    c=1
    for i in data:
        if i>0:
            X.append(c)
        c+=1
    return X

then your data without zeros in a pythonic way:

my_y_data=[i for i in data if i>0]

with data=[1,3,6,1,2,0,0,0,0,1,4,7,9,4,2,4,6,0,0,0,0,0,0,0,0,0,0,0,0,1,3,5,6,7,8]

then you can plot:

plot(x(data), my_y_data)

Hope I helped !!

Suerte.

Hasta otra.

···

On 7/18/07, Armando Serrano Lombillo <arserlom@...287...> wrote:

Hello, I have a question.

Let's say I have the following data:
[1,3,6,1,2,0,0,0,0,1,4,7,9,4,2,4,6,0,0,0,0,0,0,0,0,0,0,0,0,1,3,5,6,7,8]
which I want to plot, but I want to omit the zeros, so I would like to do
something like:
plot(range(1,6), [1,3,6,1,2], 'b')
plot(range(10,18), [1,4,7,9,4,2,4,6], 'b')
plot(range(30,36), [1,3,5,6,7,8], 'b')
savefig('filtered.eps')

Is there an elegant way of doing this?

Armando.

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_Angel_Lopez · July 18, 2007, 9:31am

Even in only one line:

plot([i+1 for i in range(len(data)) if data[i]>0], [i for i in data if i>0])

_Antonino_Ingargiola · July 18, 2007, 9:37am

You can do it this way:

data = array(data)
x = arange(len(data))
plot(x[data!=0], data[data!=0])

Regards,

~ Antonio

_Armando_Serrano_Lom · July 18, 2007, 10:01am

Hello thanks everybody for you fast replies, but unfortunately there’s a problem with all the solutions you propose: they plot a line between each of the data sets. It is not the same to do:
plot([1,2],[1,1])
plot([7,8],[1,1])

than to do
plot([1,2,7,8],[1,1,1,1])
The first example plots two disjoint segments, while the second plots three joint segments.

I did code a workaround to plot the data as I wanted but it’s something like 20 lines of ugly code and I really think there must be an easier way.

By the way, Angel, my name is Armando not Alejandro.

···

On 7/18/07, Armando Serrano Lombillo <arserlom@…287… > wrote:

Hello, I have a question.

Let’s say I have the following data:

[1,3,6,1,2,0,0,0,0,1,4,7,9,4,2,4,6,0,0,0,0,0,0,0,0,0,0,0,0,1,3,5,6,7,8]
which I want to plot, but I want to omit the zeros, so I would like to do something like:

plot(range(1,6), [1,3,6,1,2], ‘b’)
plot(range(10,18), [1,4,7,9,4,2,4,6], ‘b’)
plot(range(30,36), [1,3,5,6,7,8], ‘b’)
savefig(‘filtered.eps’)

Is there an elegant way of doing this?

Armando.

_Angus_McMorland · July 18, 2007, 10:17am

Hi Armando,

···

On 18/07/07, Armando Serrano Lombillo <arserlom@...287...> wrote:

Hello, I have a question.

Let's say I have the following data:
[1,3,6,1,2,0,0,0,0,1,4,7,9,4,2,4,6,0,0,0,0,0,0,0,0,0,0,0,0,1,3,5,6,7,8]
which I want to plot, but I want to omit the zeros, so I would like to do
something like:
plot(range(1,6), [1,3,6,1,2], 'b')
plot(range(10,18), [1,4,7,9,4,2,4,6], 'b')
plot(range(30,36), [1,3,5,6,7,8], 'b')
savefig('filtered.eps')

Is there an elegant way of doing this?

Do masked arrays achieve what you want?

from numpy.core import ma
data = n.array([1,3,6,1,2,0,0,0,0,1,4,7,9,4,2,4,6,0,0,0,0,0,0,0,0,0,0,0,0,1,3,5,6,7,8])
masked_data = ma.masked_array(data, mask=(dat==0))
plot(masked_data)

Angus.
--
AJC McMorland, PhD Student
Physiology, University of Auckland

_Armando_Serrano_Lom · July 18, 2007, 10:56am

Yes!
matplotlib is beautiful. Thanks everybody for your help.

···

On 7/18/07, Angus McMorland <amcmorl@…287… > wrote:

Hi Armando,

On 18/07/07, Armando Serrano Lombillo < > arserlom@…287…> wrote:

Hello, I have a question.

Let’s say I have the following data:
[1,3,6,1,2,0,0,0,0,1,4,7,9,4,2,4,6,0,0,0,0,0,0,0,0,0,0,0,0,1,3,5,6,7,8]
which I want to plot, but I want to omit the zeros, so I would like to do

something like:
plot(range(1,6), [1,3,6,1,2], ‘b’)
plot(range(10,18), [1,4,7,9,4,2,4,6], ‘b’)
plot(range(30,36), [1,3,5,6,7,8], ‘b’)
savefig('filtered.eps
')

Is there an elegant way of doing this?

Do masked arrays achieve what you want?

from numpy.core import ma
data = n.array([1,3,6,1,2,0,0,0,0,1,4,7,9,4,2,4,6,0,0,0,0,0,0,0,0,0,0,0,0,1,3,5,6,7,8])

masked_data = ma.masked_array(data, mask=(dat==0))
plot(masked_data)

Angus.

AJC McMorland, PhD Student
Physiology, University of Auckland

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_Darren_Dale1 · July 18, 2007, 11:11am

Yes!
matplotlib is beautiful. Thanks everybody for your help.

Here is another way, with numpy arrays:

data[data==0]=nan

plot(data)

···

On Wednesday 18 July 2007 6:56:18 am Armando Serrano Lombillo wrote:

On 7/18/07, Angus McMorland <amcmorl@...287...> wrote:
> Hi Armando,
>
> On 18/07/07, Armando Serrano Lombillo <arserlom@...287...> wrote:
> > Hello, I have a question.
> >
> > Let's say I have the following data:
> > [1,3,6,1,2,0,0,0,0,1,4,7,9,4,2,4,6,0,0,0,0,0,0,0,0,0,0,0,0,1,3,5,6,7,8]
> > which I want to plot, but I want to omit the zeros, so I would like to
>
> do
>
> > something like:
> > plot(range(1,6), [1,3,6,1,2], 'b')
> > plot(range(10,18), [1,4,7,9,4,2,4,6], 'b')
> > plot(range(30,36), [1,3,5,6,7,8], 'b')
> > savefig('filtered.eps')
> >
> > Is there an elegant way of doing this?
>
> Do masked arrays achieve what you want?
>
> from numpy.core import ma
> data = n.array
> ([1,3,6,1,2,0,0,0,0,1,4,7,9,4,2,4,6,0,0,0,0,0,0,0,0,0,0,0,0,1,3,5,6,7,8])
> masked_data = ma.masked_array(data, mask=(dat==0))
> plot(masked_data)

PGM · July 18, 2007, 3:24pm

My 2c:
That won't work if data is int_, as nan will be treated as 0.
I'm fairly partial to masked arrays...

···

On Wednesday 18 July 2007 07:11:04 Darren Dale wrote:

Here is another way, with numpy arrays:

data[data==0]=nan

Eric_Firing1 · July 18, 2007, 4:40pm

Darren Dale wrote:

···

On Wednesday 18 July 2007 6:56:18 am Armando Serrano Lombillo wrote:

Yes!
matplotlib is beautiful. Thanks everybody for your help.

Here is another way, with numpy arrays:

data[data==0]=nan

plot(data)

Support for nan in input arrays in mpl is not uniform, though, so the masked array alternative is preferred.

Eric