Re: [Matplotlib-users] Matplotlib for tiles - blank lines

[Phil E. <pel...@gm...>]

I fixed an issue related to this (I too was producing map tiles) in
matplotlib v1.2 I believe.

The original issue can be found at
https://github.com/matplotlib/matplotlib/pull/1591 and so I suggest this
might not be an issue with matplotlib >= v1.3.

Incidentally, if you are producing map tiles you might be interested in
cartopy which will allow you to produce properly referenced geo maps (and
therefore tiles) with coastlines etc.
I've put a short-sh example in a gist () with the rendered results also
available (https://rawgithub.com/pelson/9738051/raw/map.html). I've also
got a tornado based handler version which generates the tiles upon HTTP
request rather than storing the tiles on disk (much more efficient if you
have highly dynamic data and a caching layer).

Let me know if updating your matplotlib version helps,

Cheers,

Phil







On 24 March 2014 09:45, Jesper Larsen <jes...@gm...> wrote:

> Hi matplotlib users,
>
> I am using matplotlib to produce plots (tiles) in a Web Map Service.
> Unfortunately I cannot get Matplotlib to plot on the entire image. There
> are one transparent (pixel) line at the bottom and one transparent line at
> the right. This is of course a problem when the tiles are shown in a map.
> Please see example below. Can anyone see what I am doing wrong?
>
> Best regards,
> Jesper
>
> import numpy as np
> import matplotlib as mpl
> from matplotlib.figure import Figure
> from matplotlib.backends.backend_agg import FigureCanvasAgg as FigureCanvas
>
> w = 256
> h = 256
> dpi = 128
> figsize = w/dpi, h/dpi
> fig = Figure(figsize=figsize, dpi=dpi, frameon=False)
> canvas = FigureCanvas(fig)
> ax = fig.add_axes([0, 0, 1, 1])
>
> x = np.arange(0, 10, 0.1)
> y = np.arange(10, 20, 0.2)
> X, Y = np.meshgrid(x, y)
> D = np.ones((X.shape[0]-1, X.shape[1]-1))
> V = np.linspace(0.0, 1.0, 10)
> ax.pcolor(X, Y, D, antialiased=False)
> ax.axis( [x[0], x[-1], y[0], y[-1]] )
> ax.axis('off')
> filename = 'testfile.png'
> fig.savefig(filename, dpi=128)
>
> # Test image
> from PIL import Image
> im = Image.open(filename)
> print im.getcolors()
>
>
>
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