[Matplotlib-users] Problem using imshow with Matplotlib/Basemap

[Benjamin Root]

First, you shouldn't need to transpose your image... that'll effectively
rotate the data by 90 degrees. Second, you didn't specify the extents of
your image, so Basemap is putting everything starting at coordinate 0,0 in
the default projection.

If you specify the extent keyword argument to imshow as the (lon1, lat1,
lon2, lat2) tuple for the lower-left and upper right corners, you won't
even need the origin='lower', and you definitely won't need the transpose.

Cheers!
Ben Root


On Sun, Oct 8, 2017 at 2:33 PM, Mauro Cavalcanti <maurobio at gmail.com> wrote:

> Dear ALL,
>
> I have a simple dataset of longitudes/latitudes (see the attached csv
> file).
>
> From such data, I want to generate a grid like this:
>
> 0 0 0 0 0 0 0 0 0 0 0 0 0
> 0 0 0 0 0 0 0 0 0 0 0 0 0
> 0 0 0 0 0 0 0 0 0 0 0 0 0
> 0 0 0 0 0 0 1 0 0 0 0 0 0
> 0 0 0 0 0 0 1 1 2 0 0 0 0
> 0 0 0 0 0 1 1 1 1 0 0 0 0
> 0 0 0 1 0 1 0 0 0 0 0 0 0
> 0 0 0 2 0 0 0 0 0 0 0 0 0
> 0 0 0 0 0 0 0 0 0 1 3 0 0
> 0 0 0 0 0 0 0 0 0 0 0 0 0
> 0 0 0 0 0 0 0 0 0 1 0 0 0
> 0 0 0 0 0 0 0 0 0 1 0 0 0
> 0 0 0 0 0 0 0 0 0 0 0 0 0
> 0 0 0 0 0 0 0 0 0 0 1 0 0
> 0 0 0 0 0 0 0 0 0 0 1 0 0
> 0 0 0 0 0 0 0 0 0 0 0 0 0
> 0 0 0 0 0 0 0 0 0 0 0 0 0
>
> which gives the number of data records in each cell of the grid, using one
> of the variables in the dataset ("spp") as a categorical (grouping) factor.
>
> From this grid, I then want to create a heat map, superimposed on a
> Matplotlib/Basemap.
>
> I wrote some code which does what I want (see the attachments).
>
> It (mostly) works, but te problem is that the grid image is not being
> displayed correctly: as shown in the attached figure, it appears too small,
> and in the lower left corner of the map, instead of where it should be (the
> West coast of Africa, along the Gulf of Guinea).
>
> Thanks in advance for any assistance you can provide.
>
> Best regards,
>
> --
> Dr. Mauro J. Cavalcanti
> E-mail: maurobio at gmail.com
> Web: http://sites.google.com/site/maurobio
> "Life is complex. It consists of real and imaginary parts."
>
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>
>
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