| Andrew Cooke | Contents | Latest | RSS | Twitter | Previous | Next


Welcome to my blog, which was once a mailing list of the same name and is still generated by mail. Please reply via the "comment" links.

Always interested in offers/projects/new ideas. Eclectic experience in fields like: numerical computing; Python web; Java enterprise; functional languages; GPGPU; SQL databases; etc. Based in Santiago, Chile; telecommute worldwide. CV; email.

Personal Projects

Lepl parser for Python.

Colorless Green.

Photography around Santiago.

SVG experiment.

Professional Portfolio

Calibration of seismometers.

Data access via web services.

Cache rewrite.

Extending OpenSSH.

C-ORM: docs, API.

Last 100 entries

Small Success With Go!; Re: Quick message - This link is broken; Adding Reverb To The Echo Chamber; Sox Audio Tools; Would This Have Been OK?; Honesty only important economically before institutions develop; Stegangraphy via PS4; OpenCL Mess; More Book Recommendations; Good Explanation of Difference Between Majority + Minority; Musical Chairs - Who's The Privileged White Guy; I can see straight men watching this conversation and laffing; When it's Actually a Source of Indignation and Disgust; Meta Thread Defending POC Causes POC To Close Account; Indigenous People Of Chile; Curry Recipe; Interesting Link On Marginality; A Nuclear Launch Ordered, 1962; More Book Recs (Better Person); It's Nuanced, And I Tried, So Back Off; Marx; The Negative Of Positive; Jenny Holzer Rocks; Huge Article on Cultural Evolution and More; "Ignoring language theory"; Negative Finger Counting; Week 12; Communication Via Telecomm Bids; Finding Suspects Via Relatives' DNA From Non-Crime Databases; Statistics and Information Theory; Ice OK in USA; On The Other Hand; (Current Understanding Of) Chilean Taxes / Contributions; M John Harrison; Playing Games on a Cloud GPU; China Gamifies Real Life; Can't Help Thinking It's Thoughtcrime; Mefi Quotes; Spray Painting Bike Frame; Weeks 10 + 11; Change: No Longer Possible To Merge Metadata; Books on Old Age; Health Tree Maps; MRA - Men's Rights Activists; Writing Good C++14; Risk Assessment - Fukushima; The Future of Advertising and Surveillance; Travelling With Betaferon; I think I know what I dislike so much about Metafilter; Weeks 8 + 9; More; Pastamore - Bad Italian in Vitacura; History Books; Iraq + The (UK) Governing Elite; Answering Some Hard Questions; Pinochet: The Dictator's Shadow; An Outsider's Guide To Julia Packages; Nobody gives a shit; Lepton Decay Irregularity; An Easier Way; Julia's BinDeps (aka How To Install Cairo); Good Example Of Good Police Work (And Anonymity Being Hard); Best Santiago Burgers; Also; Michael Emmerich (Vibrator Translator) Interview (Japanese Books); Clarice Lispector (Brazillian Writer); Books On Evolution; Looks like Ara (Modular Phone) is dead; Index - Translations From Chile; More Emotion in Chilean Wines; Week 7; Aeon Magazine (Science-ish); QM, Deutsch, Constructor Theory; Interesting Talk Transcripts; Interesting Suggestion Of Election Fraud; "Hard" Books; Articles or Papers on depolarizing the US; Textbook for "QM as complex probabilities"; SFO Get Libor Trader (14 years); Why Are There Still So Many Jobs?; Navier Stokes Incomplete; More on Benford; FBI Claimed Vandalism; Architectural Tessellation; Also: Go, Blake's 7; Delusions of Gender (book); Crypto AG DID work with NSA / GCHQ; UNUMS (Universal Number Format); MOOCs (Massive Open Online Courses); Interesting Looking Game; Euler's Theorem for Polynomials; Weeks 3-6; Reddit Comment; Differential Cryptanalysis For Dummies; Japanese Graphic Design; Books To Be Re-Read; And Today I Learned Bugs Need Clear Examples; Factoring a 67 bit prime in your head; Islamic Geometric Art; Useful Julia Backtraces from Tasks; Nothing, however, is lost with less discomfort than that which, when lost, cannot be missed

© 2006-2015 Andrew Cooke (site) / post authors (content).

Generating SVG in Python 2.4

From: andrew cooke <andrew@...>

Date: Fri, 23 Jul 2010 10:07:27 -0400

There's not much love for Python 2.4 and SVG (which, I admit is something of
an odd combination - who would be so conservative they would use Python 2.4
and then require SVG?), particularly if you need a non-GPL solution.  So I
ended up wiring a simple wrapper around DOM that helps generate the XML.
Here's a summary of the approach (there's nothing really hard here, just
fiddly DOM details):

class SvgBase(object):
    Support class.  Contains a reference to the DOM document and
    the element corresponding to this node.  Note that we allow any
    node to be extended with any child node; we also allow any 
    attribute to be added.
    SVG = 'http://www.w3.org/2000/svg'
    def __init__(self, doc, element, **attrs):
        self._doc = doc
        self._element = element
        for name in attrs:
            value = attrs[name]
            if value is not None:
                self._element.setAttributeNS(self.SVG, name, str(value))
    def line(self, (x1, y1), (x2, y2), **attrs):
        Add a child line
        return Line(self, (x1, y1), (x2, y2), **attrs)
    # more child metods here.....

class Svg(SvgBase):
    The root svg element.  This creates the document, allows a 
    stylesheet to be used, etc.

    def __init__(self, version='1.1', width=None, height=None):
        implementation = getDOMImplementation('')
        doctype = implementation.createDocumentType('svg', 
            '-//W3C//DTD SVG 1.1//EN', 
        document = implementation.createDocument(self.SVG, 'svg', doctype)
        for node in document.childNodes:
            if node.nodeType == Node.ELEMENT_NODE:
                element = node
        # xlink lets "a" element work correctly (use xlink:href)
        ns = {'xmlns': self.SVG,
              'xmlns:xlink': 'http://www.w3.org/1999/xlink'}
        super(Svg, self).__init__(document, element, 
                                  version=version, width=width, height=height,
    def add_stylesheet(self, url):
        style = self._doc.createProcessingInstruction('xml-stylesheet',
                        'href="%s" type="text/css"' % url)
        for node in self._doc.childNodes:
            if node.nodeType == Node.DOCUMENT_TYPE_NODE:
                self._doc.insertBefore(style, node)

    def __str__(self):
        The XML of the entire document.
        return self._doc.toxml()

class Line(SvgBase):
    An example child node.

    def __init__(self, parent, (x1, y1), (x2, y2), **attrs):
        element = parent._doc.createElementNS(self.SVG, 'line')
        super(Line, self).__init__(parent._doc, element,
                                   x1=self._1dp(x1), y1=self._1dp(y1), 
                                   x2=self._1dp(x2), y2=self._1dp(y2), 

With that, it's pretty easy to do things like:

    >>> svg = Svg()
    >>> svg.line((1,2), (3,4), stroke='blue')
    >>> svg.add_stylesheet('http://example.com/foo')
    >>> str(svg)
    '''<?xml version="1.0" ?>
       <?xml-stylesheet href="http://example.com/foo" type="text/css"?>
       <!DOCTYPE svg  PUBLIC '-//W3C//DTD SVG 1.1//EN'  
       <svg version="1.1" xmlns="http://www.w3.org/2000/svg"
         <line x1="1.0" x2="3.0" y1="2.0" y2="4.0" stroke="blue"/>


Comment on this post