[reportlab-users] Minor bug in spider.py, with patch

[Max M]

In <site-packages>/reportlab/graphics/charts/spider.py there is a minor 
division
by zero bug.

If all elemnents are 0.0, theMax will also be 0.0. That will make this 
line fail
with a zero division error:

    scaledRow.append(element / theMax)


Here is the original method:

    def normalizeData(self, outer = 0.0):
        """Turns data into normalized ones where each datum is < 1.0,
        and 1.0 = maximum radius.  Adds 10% at outside edge by default"""
        data = self.data
        theMax = 0.0
        for row in data:
            for element in row:
                assert element >=0, "Cannot do spider plots of negative 
numbers!"
                if element > theMax:
                    theMax = element
        theMax = theMax * (1.0+outer)

        scaled = []
        for row in data:
            scaledRow = []
            for element in row:
                scaledRow.append(element / theMax)
            scaled.append(scaledRow)
        return scaled


And a patched version:

    def normalizeData(self, outer = 0.0):
        """Turns data into normalized ones where each datum is < 1.0,
        and 1.0 = maximum radius.  Adds 10% at outside edge by default"""
        data = self.data
        theMax = 0.0
        for row in data:
            for element in row:
                assert element >=0, "Cannot do spider plots of negative 
numbers!"
                if element > theMax:
                    theMax = element
        theMax = theMax * (1.0+outer)

        if theMax == 0.0: # all values are zero
            scaled = self.data
        else:
            scaled = []
            for row in data:
                scaledRow = []
                for element in row:
                    scaledRow.append(element / theMax)
                scaled.append(scaledRow)
        return scaled


-- 

hilsen/regards Max M, Denmark

http://www.mxm.dk/
IT's Mad Science