think I fixed it

xbatcher/generators.py

@@ -41,10 +41,13 @@ def _drop_input_dims(ds, input_dims, suffix='_input'):
     # remove input_dims coordinates from datasets, rename the dimensions
     # then put intput_dims back in as coordinates
     out = ds.copy()
-    out = (out.drop(input_dims)
-              .rename({dim: dim + suffix for dim in input_dims}))
     for dim in input_dims:
-        out.coords[dim] = dim + suffix, ds[dim].values
+        newdim = dim + suffix
+        out = out.rename({dim: newdim})
+        # extra steps needed if there is a coordinate
+        if newdim in out:
+            out = out.drop(newdim)
+            out.coords[dim] = newdim, ds[dim].data, ds[dim].attrs
     return out
 
 

xbatcher/tests/test_generators.py

@@ -50,7 +50,7 @@ def test_batch_1d_no_coordinate(sample_ds_1d, bsize):
 
 @pytest.mark.parametrize("bsize", [5, 10])
 def test_batch_1d_concat_no_coordinate(sample_ds_1d, bsize):
-    # fix for #3
+    # test for #3
     ds_dropped = sample_ds_1d.drop('x')
     bg = BatchGenerator(ds_dropped, input_dims={'x': bsize},
                         concat_input_dims=True)
@@ -60,7 +60,6 @@ def test_batch_1d_concat_no_coordinate(sample_ds_1d, bsize):
         assert ds_batch.dims['input_batch'] == sample_ds_1d.dims['x']//bsize
         assert 'x' not in ds_batch.coords
 
-
 @pytest.mark.parametrize("olap", [1, 4])
 def test_batch_1d_overlap(sample_ds_1d, olap):
     bsize = 10