[scilab-Users] heatmap / Matplot

[Nelson Mambre]

Hi Joshua,

Don't have Scilab installed right now, but maybe contour or contour2d 
could help you, if they are more or less the same as contourf in Matlab.

Nelson.

Joshua Auerbach wrote:
> Thanks for the info on grayplot.  A little confusing that something 
> that plots colors would be called "gray"plot don't you think?
>
> In any case, this almost gets me to where I want, except grayplot 
> determines the color for each rectangle from the average value at each 
> corner and I do not want this.  I want each rectangle to only take its 
> color from one value (what is at the center of the rectangle).  ie if 
> my z matrix is binary I want to only see two colors but with grayplot 
> i will get a color for 0 (all four corners 0), 0.25 (one corner 1), 
> 0.5 (two corners 1), 0.75 (three corners 1) and 1 (all four corners 1).
>
> Any advice on how to do that?
>
> Thanks,
> Josh
>
> duboism at limsi.fr wrote:
>> Hi Joshua,
>>
>> I think that the function grayplot (and its friends fgrayplot, 
>> Sgrayplot)
>> would be useful for you but you will have to reformat your data.
>>
>> grayplot takes 3 arguments: x (vector of x coordinates, size nx), y
>> (vector of y coordinates, size ny) and a nx*ny matrix data (the value at
>> data(i,j) is the value of point (x(i), y(j)) ). See the script
>> test_grayplot.sce.
>>
>> It should not be hard to re-format your data this way.
>>
>> Note the use of the zminmax option to plot different data with the same
>> color scale (see test_grayplot2.sce).
>> Note also that on the x86_64 architecture the function colorbar seems
>> broken (in fact you cannot use it since it raises an error).
>>
>> Mathieu
>>
>>  
>>> Hi,
>>>
>>> I am looking for some assistance.  I am trying to make what I know as a
>>> heatmap.  Basically I have data for many points on a grid and want to
>>> construct a 2d plot where each point is given a color on a gradient
>>> (From blue to red say) based on the data value at that point.  I have
>>> the data in the form of a matrix with 3 columns x-coord, y-coord, data
>>> value
>>>
>>> Currently I am making this type of plot by transforming my grid
>>> coordinates into matrix coordinates of a new matrix and scaling my data
>>> values into the range [0, NUM_COLORS] and using the Matplot function to
>>> plot this data.  This method does work, but has a few shortcomings: I
>>> lose the original scale of my grid since the axis labels are based on
>>> the matrix coordinates.  There is no key explaining the gradient and
>>> even if there were I would lose the original scale of my data values.
>>>
>>> Does anyone know how to get around these limitations or know of a 
>>> better
>>> way to accomplish what I am trying to do?  I'd appreciate any help.
>>>
>>> Cheers,
>>> Josh
>>>
>>>     
>
>