# Specifying X,Y Pairs For Line Plots

Rich Shepard <rshepard@...83...> writes:

x,y = [(15.0, 0.0), (30.0, 1.0), (70.0, 1.0), (85.0, 0.0)]
ValueError: too many values to unpack

You are looking for the classic "unzip" trick:

x,y = zip(*[(15.0, 0.0), (30.0, 1.0), (70.0, 1.0), (85.0, 0.0)])

···

--
Jouni

Jouni,

That's totally new to me. I'll go find out what it is and how it works its
magic.

Thank you,

Rich

···

On Sun, 25 Nov 2007, Jouni K Seppänen wrote:

You are looking for the classic "unzip" trick:
x,y = zip(*[(15.0, 0.0), (30.0, 1.0), (70.0, 1.0), (85.0, 0.0)])

--
Richard B. Shepard, Ph.D. | Integrity Credibility
Applied Ecosystem Services, Inc. | Innovation
<http://www.appl-ecosys.com> Voice: 503-667-4517 Fax: 503-667-8863

Jouni,

Thank you for pointing this out to me. I see that it's a builtin function
similar to map that assembles the first element of each tuple into a list
for the first variable, and the second element of each tuple into a list for
the second variable. How useful for my plotting needs!

Rich

···

On Sun, 25 Nov 2007, Jouni K Seppänen wrote:

x,y = zip(*[(15.0, 0.0), (30.0, 1.0), (70.0, 1.0), (85.0, 0.0)])

--
Richard B. Shepard, Ph.D. | Integrity Credibility
Applied Ecosystem Services, Inc. | Innovation
<http://www.appl-ecosys.com> Voice: 503-667-4517 Fax: 503-667-8863

Rich Shepard wrote:

x,y = zip(*[(15.0, 0.0), (30.0, 1.0), (70.0, 1.0), (85.0, 0.0)])

or better yet -- work with numpy arrays from the beginning:

Either put x an y into separate arrays (which is what MPL expects), or if you like X and Y begin together (I do):

points = numpy.array([(15.0, 0.0), (30.0, 1.0), (70.0, 1.0), (85.0, 0.0)])

x = points[:,0]
y = points[:,1]

and:

p0 = points[0]
p1 = points[1]

etc. etc.

-Chris

···

--
Christopher Barker, Ph.D.
Oceanographer

Emergency Response Division
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Chris.Barker@...259...

Chris,

These values are retrieved from widgets on a notebook page and the plot
will be used to display them on that tab. It would take more code to
convert those values to a numpy array.

Rich

···

On Mon, 26 Nov 2007, Christopher Barker wrote:

or better yet -- work with numpy arrays from the beginning:

--
Richard B. Shepard, Ph.D. | Integrity Credibility
Applied Ecosystem Services, Inc. | Innovation
<http://www.appl-ecosys.com> Voice: 503-667-4517 Fax: 503-667-8863