Processing the Data for Gnuplot

In order to generate an image, we must turn the data into something that Gnuplot can understand. Gnuplot wants the data in the following format:

x0 y0 z(0, 0)
x1 y0 z(1, 0)
x2 y0 z(2, 0)
...
xN y0 z(N, 0)

x0 y1 z(0, 1)
x1 y1 z(1, 1)
x2 y1 z(2, 1)
...
xN y1 z(N, 1)

...

x0 yN z(0, N)
x1 yN z(1, N)
x2 yN z(2, N)
...
xN yN z(N, N)

This is each coordinate (x, y, z) on a separate line, with every 'row' (new y coordinate) separated with an extra newline.

This is produced from the data in the worksheet, using the GenerateGnuplotData function in the plot module:

def GenerateGnuplotData(sheet):
    out = []
    for y in range(1, sheet.MaxRow + 1):
        row = []
        for x in range(1, sheet.MaxCol + 1):
            value = sheet[x, y]
            u = (6.0 / 50) * x - 3
            v = (6.0 / 50) * y - 3
            row.append('%s %s %s' % (u, v, value))
        out.append(row)
    return '\n\n    '.join('\n    '.join(row) for row in out)