issue_comments

Ho, sorry... I just see the PR...

Hi, I was looking to some xarray padding function and get this issue. For the moment, I made a function of my own based on numpy.pad and xr.apply_ufunc When possible, it also pad associated coordinates. If it can be of any help here... Here it is: ``` def xpad(ds, dims={}): """ Padding of xarray. Coordinate are linearly padded if original coordinates are evenly spaced. Otherwise, no new coordinates are affected to padded axis. Padded dimension is named with prefix 'padded_'

Args:
    ds (xarray): xarray
    dims (dict): keys are dimensions along which to pad and values are padding tuple (see np.pad). (ex {'pulse:(10,0)})

Returns:
    (xarray) : same as input with padded axis. 
"""
mypad = [(0,0) for n in ds.dims if n not in dims.keys()]
mypad+=list(dims.values())
padded_ds = xr.apply_ufunc(np.pad, ds, mypad,input_core_dims=[list(dims.keys()),[]], output_core_dims=[['padded_'+d for d in dims.keys()]], keep_attrs=True)

for var, ext in dims.items():
    dvar = np.diff(ds[var])
    if np.allclose(dvar, dvar[0]):
        dvar = dvar[0]
        left_bound, right_bound  = (np.min(ds[var]).data, np.max(ds[var]).data) if dvar>0. else (np.max(ds[var]).data, np.min(ds[var]).data)
        extended_var = np.append(ds[var].data, np.max(ds[var]).data+np.arange(1,ext[1]+1)*dvar)
        extended_var = np.append(np.min(ds[var]).data+np.arange(-ext[0],0)*dvar, extended_var)
        padded_ds = padded_ds.assign_coords(**{'padded_'+var:extended_var})
    else:
        print('Coordinates {} are not evenly spaced, padding is impossible'.format(var))
return padded_ds

```

I will create a WIP pull request tommorow.

Also see #3587

You can copy over dask.array.pad to dask_array_compat.py and do something like

python if LooseVersion(dask_version) >= LooseVersion("1.7.0"): pad = dask.array.pad else: # copied from dask.array def pad(...): ...

mode="mean" converts an array of integers to floats in Dask, but in numpy it keeps it an array of integers.

That's weird. Open an issue at the dask repo with an example?

Feel free to open an in-progress PR. Thanks for working on this.

@dcherian Thx! I found the Variable.pad_with_fill_value already, but I will also have a look at rolling and coarsen.

I have some questions related to this issue, I hope this is the correct place to ask those:

Dask added the pad method in version 1.7.0 according to its documentation. What is the minimum version of Dask that should be supported, I found Dask=1.2 is the continuous integration requirements.

Also, how should I handle implementation differences between numpy and Dask? E.g. in the current version of Dask and numpy I'm using: mode="mean" converts an array of integers to floats in Dask, but in numpy it keeps it an array of integers.

@mark-boer Note that we have a Variable.pad_with_fill_value method and some other padding code in rolling and coarsen that could be consolidated.

@mark-boer - I don't think so. Give it a go!

Has some1 started working on this? I thought I might give it a try ;-)