[WIP] Make sure xarray.polyfit does not rechunk datarray #117
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navidcy
changed the title
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@@ Coverage Diff @@
## master #117 +/- ##
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Coverage 98.31% 98.31%
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Files 2 2
Lines 830 831 +1
Branches 118 118
=======================================
+ Hits 816 817 +1
Misses 7 7
Partials 7 7
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rabernat
reviewed
Oct 30, 2020
| @@ -141,7 +141,8 @@ def _apply_detrend(da, dim, axis_num, detrend_type): | |||
| if len(dim) == 1: | |||
| p = da.polyfit(dim=dim[0], deg=1) | |||
| linear_fit = xr.polyval(da[dim[0]], p.polyfit_coefficients) | |||
| return da - linear_fit | |||
| da_detrended = (da - linear_fit).chunk(da.chunks) # see discussion in https://github.com/xgcm/xrft/issues/116 | |||
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This will not fix the problem. Instead this just creates a new layer of chunks in the task graph. The "upstream" tasks, which have the problems described in #116, still exist and have to be computed before we get to the new chunks. So actually this makes things worse by increasing the total number of tasks.
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FYI, I am working on this a bit. |
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Out of principle,
xrftshould not be rechunking the users input on the background. This PR is a "hack" for what supposed to be an issue withxarray.polyfit()(see #116 and pydata/xarray#4554).xarray.polyfit()seems to be rechunking the data andxrftcallsxarray.polyfit()when the user asks for a linear detrend of the input ofxrft.dft(). The proposed change simply makes sure that the detrended data array has the same chunking as the original one.Closes #116