# Pygmt grdimage fail

**URL:** <https://forum.generic-mapping-tools.org/t/pygmt-grdimage-fail/4808>\
**Category:** PyGMT Q&A\
**Created:** [April 17, 2024, 4:26am UTC](https://forum.generic-mapping-tools.org/t/pygmt-grdimage-fail/4808 "2024-04-17T04:26:44Z")\
**Posts on this page:** 5\
**Page:** 1

<div class="post-metadata">

**Author:** ![dpath2o](https://yyz1.discourse-cdn.com/flex047/user_avatar/forum.generic-mapping-tools.org/dpath2o/32/1732_2.png) [@dpath2o](https://forum.generic-mapping-tools.org/u/dpath2o)\
**Post date:** [April 17, 2024, 4:26am UTC](https://forum.generic-mapping-tools.org/t/pygmt-grdimage-fail/4808/1 "2024-04-17T04:26:44Z")

</div>

Data does not plot.

```auto
spd = np.sqrt( iced.uvel.values **2 + iced.vvel.values** 2 )
spd[spd>5] = np.nan
P_save = os.path.join(D_save,"0p1","19971001_ice_speed.png")
da = xr.DataArray(data=spd, dims=["y", "x"], coords=dict(lon=(["y","x"], np.abs(ULON)), lat=(["y","x"], ULAT)))
print(da)
print(f"min: {da.min()}")
print(f"max: {da.max()}")
fig = pygmt.Figure()
pygmt.makecpt(cmap="cmocean/speed", series=[0, 1.6, .05])
fig.coast(region=[0,360,-90,-50], projection="S0/-90/12c", frame="ag", land="gray")
fig.grdimage( grid=da, projection="S0/-90/12c", frame=["WSrt+tice speed", "xa0.1", "ya0.1"], cmap=True )
fig.show()

```

> \<xarray.DataArray (y: 2700, x: 3600)\>  
> array([[nan, nan, nan, …, nan, nan, nan],  
> [nan, nan, nan, …, nan, nan, nan],  
> [nan, nan, nan, …, nan, nan, nan],  
> …,  
> [nan, nan, nan, …, nan, nan, nan],  
> [nan, nan, nan, …, nan, nan, nan],  
> [nan, nan, nan, …, nan, nan, nan]])  
> Coordinates:  
> lon (y, x) float64 279.9 279.8 279.7 279.6 … 80.0 80.0 80.0 80.0  
> lat (y, x) float64 -81.09 -81.09 -81.09 -81.09 … 65.08 65.04 64.99  
> Dimensions without coordinates: y, x  
> min: \<xarray.DataArray ()\>  
> array(0.)  
> max: \<xarray.DataArray ()\>  
> array(1.59320265)  
> makecpt [WARNING]: cmocean/speed is a discrete CPT. You can stretch it (-T/) but not interpolate it (-T//).  
> makecpt [WARNING]: Selecting the given range and ignoring the increment setting.  
> grdimage [WARNING]: Your grid y’s or latitudes appear to be outside the map region and will be skipped.  
> grdimage [WARNING]: No grid or image inside plot domain

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<div class="post-metadata">

**Author:** ![Trevor](https://yyz1.discourse-cdn.com/flex047/user_avatar/forum.generic-mapping-tools.org/trevor/32/1780_2.png) [@Trevor](https://forum.generic-mapping-tools.org/u/Trevor)\
**Post date:** [April 17, 2024, 1:55pm UTC](https://forum.generic-mapping-tools.org/t/pygmt-grdimage-fail/4808/2 "2024-04-17T13:55:39Z")

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At first inspection, looks like the da’s lat values are inconsistent with your region limits

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<div class="post-metadata">

**Author:** ![dpath2o](https://yyz1.discourse-cdn.com/flex047/user_avatar/forum.generic-mapping-tools.org/dpath2o/32/1732_2.png) [@dpath2o](https://forum.generic-mapping-tools.org/u/dpath2o)\
**Post date:** [April 18, 2024, 6:53pm UTC](https://forum.generic-mapping-tools.org/t/pygmt-grdimage-fail/4808/3 "2024-04-18T18:53:54Z")

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Thanks Trevor. Actually grid contains full globe. I think the problem is that GMT is inflexible when dealing with weird grids like this one – i.e. one with longitudes that go from -280 to 80. It would be nice if GMT (and by extension PyGMT) had more flexibility. For instance, I can plot this grid up in cartopy witout complaints/fail, but I prefer GMT because it is far superior, but unfortunately pretty rigid.

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<div class="post-metadata">

**Author:** ![Joaquim](https://yyz1.discourse-cdn.com/flex047/user_avatar/forum.generic-mapping-tools.org/joaquim/32/16_2.png) [@Joaquim](https://forum.generic-mapping-tools.org/u/Joaquim)\
**Post date:** [April 18, 2024, 7:20pm UTC](https://forum.generic-mapping-tools.org/t/pygmt-grdimage-fail/4808/4 "2024-04-18T19:20:31Z")

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GMT accepts longitudes in range [-720 720], I believe.

This produces one figure

```auto
gmt grdmath -R-280/80/-60/60 -I1 -fg X Y MUL = lixo.grd
gmt grdimage lixo.grd -JX14 -Ba -jpg lixo

```

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<div class="post-metadata">

**Author:** ![weiji14](https://yyz1.discourse-cdn.com/flex047/user_avatar/forum.generic-mapping-tools.org/weiji14/32/33_2.png) [@weiji14](https://forum.generic-mapping-tools.org/u/weiji14)\
**Post date:** [April 19, 2024, 4:41am UTC](https://forum.generic-mapping-tools.org/t/pygmt-grdimage-fail/4808/5 "2024-04-19T04:41:52Z")

</div>

Your `xarray.DataArray` was constructed incorrectly, the `lon` and `lat` coordinates should be a 1D array instead of a mesh. Try something like this (using random data):

```python
import numpy as np
import pygmt
import xarray as xr

spd = np.random.rand(2700, 3600)
ULON = np.linspace(start=-279.9, stop=80, num=3600)
ULAT = np.linspace(start=-81.09, stop=64.99, num=2700)
da = xr.DataArray(data=spd, dims=["y", "x"], coords=dict(x=ULON, y=ULAT))
print(da)
print(f"min: {da.min()}")
print(f"max: {da.max()}")

# %%
fig = pygmt.Figure()
pygmt.makecpt(cmap="cmocean/speed", series=[0, 1.6, 0.05])
fig.coast(region=[0, 360, -90, -50], projection="S0/-90/12c", frame="ag", land="gray")
fig.grdimage(
    grid=da,
    projection="S0/-90/12c",
    frame=["WSrt+tice speed", "xa0.1", "ya0.1"],
    cmap=True,
)
fig.show()

```

produces

 ![random_ice_speed](https://canada1.discourse-cdn.com/flex047/uploads/gmt/original/2X/f/f5b5643e458aecf35631b5592fde7760b13a4d0e.jpeg)

That said, I’m not sure if it’s easy for you to modify your ULON and ULAT arrays to fit into this scheme. GMT/PyGMT should be able to plot -280/80 data as Joaquim mentioned above, and you shouldn’t need to do `np.abs(ULON)` (that would make the coordinates unsorted).