[Vision] specifying the column(s) for data to be plotted

Michel Sanner, PhD sanner at scripps.edu
Mon Apr 19 08:47:37 PDT 2010

Hello Brad

Thanks for your interest in Vision. The data coming out of ReadTable is 
a numpy array see http://docs.scipy.org/doc/
You can slice the data using numpy syntax in a "Slice Data" node from 
the standard library.

For example:

[:,0] would give you the first column
[:,1] second column

[2,:] the second row
the syntax is a comma (,) separated list for each dimension of the array.
Dimensions are C style (i.e. lines first columns next).
For each dimension you can specify a number or a range using "from:to"
omitting from defaults to 0, and omitting to defaults to the last element.
You can use negative indices to index from the end

writing this I realize we should have a get column and get row node to 
abstract numpy slicing syntax from users !

Id, be interested to know more about the kinbd of work you are doing. 
The usefulness of Vision has been questioned
recently and I have been told to find out what Vision users are using it 
for. So if you could spare a few minutes to tell me
it would be greatly appreciated


Brad Reisfeld wrote:
> Hi,
> I have just downloaded the MGL Tools v1.5.4 and am very interested
> in using Vision for some of my data processing; it looks like a
> really useful package.
> I typically have data stored in csv files and am interested in
> analyzing and plotting those data. As a first step, I wanted to try
> some plotting. I pulled down the 'ReadTable' widget and used it to
> read my data. I then loaded the matplotlib library and pulled down a
> 'Histogram' widget. I then connected the widgets together to build a
> histogram. This works fine.
> Now, I would like to change the data column to be plotted. How do I
> specify this? Is there another widget that should be used? I
> anticipate that this will be an issue for scatter and other kinds of
> plots as well.
> Thanks.
> Best Regards,
> Brad
> _______________________________________________
> Vision mailing list
> Vision at scripps.edu
> http://mgldev.scripps.edu/mailman/listinfo/vision


  /    Michel F. Sanner Ph.D.            The Scripps Research Institute
o     Associate Professor               Department of Molecular Biology
  \                                      10550 North Torrey Pines Road
   o   Tel. (858) 784-7742               La Jolla, CA 92037, TPC 26
  /    Fax. (858) 784-2341
o     sanner at scripps.edu                http://www.scripps.edu/~sanner

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