How to update `xarray.DataArray` using `.sel()` indexer?

Question

I found the easiest way to visualize creating a N-dimensional DataArray was to make a np.ndarray and then fill in the values by the coordinates I've created. When I tried to actually do it, I couldn't figure out how to update the xr.DataArray.

How can I update the xr.DataArray I've initialized using the labels I've created? My actual data is a much more complicated dataset but this sums up what I'm trying to do. I can use .loc but sometimes my ndarrays get huge and complicated where I don't really know the order of the dims.

# Construct DataArray
DA = xr.DataArray(np.ndarray((3,3,5)), dims=["axis_A","axis_B","axis_C"], coords={"axis_A":["A_%d"%_ for _ in range(3)],
                                                                                  "axis_B":["B_%d"%_ for _ in range(3)],
                                                                                 "axis_C":["C_%d"%_ for _ in range(5)]})
# <xarray.DataArray (axis_A: 3, axis_B: 3, axis_C: 5)>
# array([[[ 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.]]])
# Coordinates:
#   * axis_B   (axis_B) <U3 'B_0' 'B_1' 'B_2'
#   * axis_A   (axis_A) <U3 'A_0' 'A_1' 'A_2'
#   * axis_C   (axis_C) <U3 'C_0' 'C_1' 'C_2' 'C_3' 'C_4'

# # Update? 
DA.sel(axis_A="A_1", axis_B="B_1", axis_C="C_1").values = 1
DA.max()
# # <xarray.DataArray ()>
# # array(0.0)

DA.sel(axis_A="A_1", axis_B="B_1", axis_C="C_1") = 1
# #  File "<ipython-input-17-8feb7332633f>", line 4
# #     DA.sel(axis_A="A_1", axis_B="B_1", axis_C="C_1") = 1
# #                                                         ^
# # SyntaxError: can't assign to function call

Answer 1

This is really awkward, due to the unfortunate limitation of Python syntax that keyword arguments are not supported in inside square bracket.

So instead, you need to put the arguments to .sel as a dictionary in .loc instead:

DA.loc[dict(axis_A="A_1", axis_B="B_1", axis_C="C_1")] = 1