{"schema_version":"4.0","kind":"technical_task_solution","page":{"title":"How do you fix xarray DataArray.expand_dims returning a read-only array so .loc updates only one value?","url":"https://agent-solution.dev/tasks/pydata-xarray-valueerror-expand-dims","manifest_url":"https://agent-solution.dev/tasks/pydata-xarray-valueerror-expand-dims/agent.json","description":"pydata/xarray — ValueError in expand_dims. Traceback path: xarray/core/dataarray.py. Match the exact symbols, paths, and error text on the page.","updated_at":"2026-08-27"},"task_match":{"technology":"pydata/xarray","error_signature":"ValueError","focus_symbol":"expand_dims","focus_path":"xarray/core/dataarray.py","problem_class":"python-traceback-repairs","statement_kind":"verbatim agent-facing issue statement","task_statement":"expand_dims() modifies numpy.ndarray.flags to write only, upon manually reverting this flag back, attempting to set a single inner value using .loc will instead set all of the inner array values\nI am using the newly updated **expand_dims** API that was recently updated with this PR [https://github.com/pydata/xarray/pull/2757](https://github.com/pydata/xarray/pull/2757). However the flag setting behaviour can also be observed using the old API syntax.\r\n\r\n```python\r\n>>> expanded_da = xr.DataArray(np.random.rand(3,3), coords={'x': np.arange(3), 'y': np.arange(3)}, dims=('x', 'y')) # Create a 2D DataArray\r\n>>> expanded_da\r\n<xarray.DataArray (x: 3, y: 3)>\r\narray([[0.148579, 0.463005, 0.224993],\r\n       [0.633511, 0.056746, 0.28119 ],\r\n       [0.390596, 0.298519, 0.286853]])\r\nCoordinates:\r\n  * x        (x) int64 0 1 2\r\n  * y        (y) int64 0 1 2\r\n\r\n>>> expanded_da.data.flags # Check current state of numpy flags\r\n  C_CONTIGUOUS : True\r\n  F_CONTIGUOUS : False\r\n  OWNDATA : True\r\n  WRITEABLE : True\r\n  ALIGNED : True\r\n  WRITEBACKIFCOPY : False\r\n  UPDATEIFCOPY : False\r\n\r\n>>> expanded_da.loc[0, 0] = 2.22 # Set a single value before expanding\r\n>>> expanded_da # It works, the single value is set\r\n<xarray.DataArray (x: 3, y: 3)>\r\narray([[2.22    , 0.463005, 0.224993],\r\n       [0.633511, 0.056746, 0.28119 ],\r\n       [0.390596, 0.298519, 0.286853]])\r\nCoordinates:\r\n  * x        (x) int64 0 1 2\r\n  * y        (y) int64 0 1 2\r\n\r\n>>> expanded_da = expanded_da.expand_dims({'z': 3}, -1) # Add a new dimension 'z'\r\n>>> expanded_da\r\n<xarray.DataArray (x: 3, y: 3, z: 3)>\r\narray([[[2.22    , 2.22    , 2.22    ],\r\n        [0.463005, 0.463005, 0.463005],\r\n        [0.224993, 0.224993, 0.224993]],\r\n\r\n       [[0.633511, 0.633511, 0.633511],\r\n        [0.056746, 0.056746, 0.056746],\r\n        [0.28119 , 0.28119 , 0.28119 ]],\r\n\r\n       [[0.390596, 0.390596, 0.390596],\r\n        [0.298519, 0.298519, 0.298519],\r\n        [0.286853, 0.286853, 0.286853]]])\r\nCoordinates:\r\n  * x        (x) int64 0 1 2\r\n  * y        (y) int64 0 1 2\r\nDimensions without coordinates: z\r\n\r\n>>> expanded_da['z'] = np.arange(3) # Add new coordinates to the new dimension 'z'\r\n>>> expanded_da\r\n<xarray.DataArray (x: 3, y: 3, z: 3)>\r\narray([[[2.22    , 2.22    , 2.22    ],\r\n        [0.463005, 0.463005, 0.463005],\r\n        [0.224993, 0.224993, 0.224993]],\r\n\r\n       [[0.633511, 0.633511, 0.633511],\r\n        [0.056746, 0.056746, 0.056746],\r\n        [0.28119 , 0.28119 , 0.28119 ]],\r\n\r\n       [[0.390596, 0.390596, 0.390596],\r\n        [0.298519, 0.298519, 0.298519],\r\n        [0.286853, 0.286853, 0.286853]]])\r\nCoordinates:\r\n  * x        (x) int64 0 1 2\r\n  * y        (y) int64 0 1 2\r\n  * z        (z) int64 0 1 2\r\n\r\n>>> expanded_da.loc[0, 0, 0] = 9.99 # Attempt to set a single value, get 'read-only' error\r\nTraceback (most recent call last):\r\n  File \"<stdin>\", line 1, in <module>\r\n  File \"/Users/dhemming/.ve/unidata_notebooks/lib/python3.6/site-packages/xarray/core/dataarray.py\", line 113, in __setitem__\r\n    self.data_array[pos_indexers] = value\r\n  File \"/Users/dhemming/.ve/unidata_notebooks/lib/python3.6/site-packages/xarray/core/dataarray.py\", line 494, in __setitem__\r\n    self.variable[key] = value\r\n  File \"/Users/dhemming/.ve/unidata_notebooks/lib/python3.6/site-packages/xarray/core/variable.py\", line 714, in __setitem__\r\n    indexable[index_tuple] = value\r\n  File \"/Users/dhemming/.ve/unidata_notebooks/lib/python3.6/site-packages/xarray/core/indexing.py\", line 1174, in __setitem__\r\n    array[key] = value\r\nValueError: assignment destination is read-only\r\n\r\n>>> expanded_da.data.flags # Check flags on the DataArray, notice they have changed\r\n  C_CONTIGUOUS : False\r\n  F_CONTIGUOUS : False\r\n  OWNDATA : False\r\n  WRITEABLE : False\r\n  ALIGNED : True\r\n  WRITEBACKIFCOPY : False\r\n  UPDATEIFCOPY : False\r\n\r\n>>> expanded_da.data.setflags(write = 1) # Make array writeable again\r\n>>> expanded_da.data.flags\r\n  C_CONTIGUOUS : False\r\n  F_CONTIGUOUS : False\r\n  OWNDATA : False\r\n  WRITEABLE : True\r\n  ALIGNED : True\r\n  WRITEBACKIFCOPY : False\r\n  UPDATEIFCOPY : False\r\n\r\n>>> expanded_da.loc[0, 0, 0] # Check the value I want to overwrite\r\n<xarray.DataArray ()>\r\narray(2.22)\r\nCoordinates:\r\n    x        int64 0\r\n    y        int64 0\r\n    z        int64 0\r\n\r\n>>> expanded_da.loc[0, 0, 0] = 9.99 # Attempt to overwrite single value, instead it overwrites all values in the array located at [0, 0]\r\n>>> expanded_da\r\n<xarray.DataArray (x: 3, y: 3, z: 3)>\r\narray([[[9.99    , 9.99    , 9.99    ],\r\n        [0.463005, 0.463005, 0.463005],\r\n        [0.224993, 0.224993, 0.224993]],\r\n\r\n       [[0.633511, 0.633511, 0.633511],\r\n        [0.056746, 0.056746, 0.056746],\r\n        [0.28119 , 0.28119 , 0.28119 ]],\r\n\r\n       [[0.390596, 0.390596, 0.390596],\r\n        [0.298519, 0.298519, 0.298519],\r\n        [0.286853, 0.286853, 0.286853]]])\r\nCoordinates:\r\n  * x        (x) int64 0 1 2\r\n  * y        (y) int64 0 1 2\r\n  * z        (z) int64 0 1 2\r\n```\r\n#### Problem description\r\n\r\nWhen applying the operation '**expand_dims({'z': 3}, -1)**' on a DataArray the underlying Numpy array flags are changed. 'C_CONTIGUOUS' is set to False, and 'WRITEABLE' is set to False, and 'OWNDATA' is set to False.  Upon changing 'WRITEABLE' back to True, when I try to set a single value in the DataArray using the '.loc' operator it will instead set all the values in that selected inner array.\r\n\r\nI am new to Xarray so I can't be entirely sure if this expected behaviour.  Regardless I would expect that adding a new dimension to the array would not make that array 'read-only'.  I would also not expect the '.loc' method to work differently to how it would otherwise.\r\n\r\nIt's also not congruent with the Numpy '**expand_dims**' operation.  Because when I call the operation 'np.expand_dims(np_arr, axis=-1)' the 'C_CONTIGUOUS ' and 'WRITEABLE ' flags will not be modified.\r\n\r\n#### Expected Output\r\n\r\nHere is a similar flow of operations that demonstrates the behaviour I would expect from the DataArray after applying 'expand_dims':\r\n\r\n```python\r\n>>> non_expanded_da = xr.DataArray(np.random.rand(3,3,3), coords={'x': np.arange(3), 'y': np.arange(3)}, dims=('x', 'y', 'z')) # Create the new DataArray to be in the same state as I would expect it to be in after applying the operation 'expand_dims({'z': 3}, -1)'\r\n>>> non_expanded_da\r\n<xarray.DataArray (x: 3, y: 3, z: 3)>\r\narray([[[0.017221, 0.374267, 0.231979],\r\n        [0.678884, 0.512903, 0.737573],\r\n        [0.985872, 0.1373  , 0.4603  ]],\r\n\r\n       [[0.764227, 0.825059, 0.847694],\r\n        [0.482841, 0.708206, 0.486576],\r\n        [0.726265, 0.860627, 0.435101]],\r\n\r\n       [[0.117904, 0.40569 , 0.274288],\r\n        [0.079321, 0.647562, 0.847459],\r\n        [0.57494 , 0.578745, 0.125309]]])\r\nCoordinates:\r\n  * x        (x) int64 0 1 2\r\n  * y        (y) int64 0 1 2\r\nDimensions without coordinates: z\r\n\r\n>>> non_expanded_da.data.flags # Check flags\r\n  C_CONTIGUOUS : True\r\n  F_CONTIGUOUS : False\r\n  OWNDATA : True\r\n  WRITEABLE : True\r\n  ALIGNED : True\r\n  WRITEBACKIFCOPY : False\r\n  UPDATEIFCOPY : False\r\n\r\n>>> non_expanded_da['z'] = np.arange(3) # Set coordinate for dimension 'z'\r\n>>> non_expanded_da\r\n<xarray.DataArray (x: 3, y: 3, z: 3)>\r\narray([[[0.017221, 0.374267, 0.231979],\r\n        [0.678884, 0.512903, 0.737573],\r\n        [0.985872, 0.1373  , 0.4603  ]],\r\n\r\n       [[0.764227, 0.825059, 0.847694],\r\n        [0.482841, 0.708206, 0.486576],\r\n        [0.726265, 0.860627, 0.435101]],\r\n\r\n       [[0.117904, 0.40569 , 0.274288],\r\n        [0.079321, 0.647562, 0.847459],\r\n        [0.57494 , 0.578745, 0.125309]]])\r\nCoordinates:\r\n  * x        (x) int64 0 1 2\r\n  * y        (y) int64 0 1 2\r\n  * z        (z) int64 0 1 2\r\n\r\n>>> non_expanded_da.loc[0, 0, 0] = 2.22 # Set value using .loc method\r\n>>> non_expanded_da # The single value referenced is set which is what I expect to happen\r\n<xarray.DataArray (x: 3, y: 3, z: 3)>\r\narray([[[2.22    , 0.374267, 0.231979],\r\n        [0.678884, 0.512903, 0.737573],\r\n        [0.985872, 0.1373  , 0.4603  ]],\r\n\r\n       [[0.764227, 0.825059, 0.847694],\r\n        [0.482841, 0.708206, 0.486576],\r\n        [0.726265, 0.860627, 0.435101]],\r\n\r\n       [[0.117904, 0.40569 , 0.274288],\r\n        [0.079321, 0.647562, 0.847459],\r\n        [0.57494 , 0.578745, 0.125309]]])\r\nCoordinates:\r\n  * x        (x) int64 0 1 2\r\n  * y        (y) int64 0 1 2\r\n  * z        (z) int64 0 1 2\r\n```\r\n\r\n#### Output of ``xr.show_versions()``\r\n\r\n<details>\r\nINSTALLED VERSIONS\r\n------------------\r\ncommit: None\r\npython: 3.6.7 (default, Dec 29 2018, 12:05:36)\r\n[GCC 4.2.1 Compatible Apple LLVM 10.0.0 (clang-1000.11.45.5)]\r\npython-bits: 64\r\nOS: Darwin\r\nOS-release: 18.2.0\r\nmachine: x86_64\r\nprocessor: i386\r\nbyteorder: little\r\nLC_ALL: None\r\nLANG: en_AU.UTF-8\r\nLOCALE: en_AU.UTF-8\r\nlibhdf5: 1.10.2\r\nlibnetcdf: 4.4.1.1\r\n\r\nxarray: 0.12.1\r\npandas: 0.24.2\r\nnumpy: 1.16.2\r\nscipy: 1.2.1\r\nnetCDF4: 1.5.0\r\npydap: None\r\nh5netcdf: None\r\nh5py: None\r\nNio: None\r\nzarr: None\r\ncftime: 1.0.3.4\r\nnc_time_axis: None\r\nPseudonetCDF: None\r\nrasterio: None\r\ncfgrib: 0.9.6.1.post1\r\niris: None\r\nbottleneck: None\r\ndask: None\r\ndistributed: None\r\nmatplotlib: 3.0.3\r\ncartopy: 0.17.0\r\nseaborn: None\r\nsetuptools: 39.0.1\r\npip: 10.0.1\r\nconda: None\r\npytest: None\r\nIPython: None\r\nsphinx: None\r\n\r\n</details>","technical_objective":"Fix DataArray.expand_dims so the resulting object behaves like a normal, independently writable array. The deliverable covers both symptoms the reporter demonstrates: the expanded array must not come back with its underlying buffer marked non-writable, and assigning to a single element through label-based indexing must change only that element.","success_condition":"after expanding a dimension, a single-element .loc assignment succeeds without a read-only error and leaves every other element untouched; the flags on the underlying array are consistent with an ordinary owned array; and existing expand_dims semantics (resulting dims, coords, order, and lazy/dask-backed cases) are preserved.","upstream_source":{"repository":"pydata/xarray","commit":"b3ba4ba5f9508e4b601d9cf5dbcd9024993adf37","version":"0.12"},"primary_terms":["ValueError","expand_dims","xarray/core/dataarray.py","pydata/xarray","DataArray",".loc","__setitem__","Variable","set_dims","np.expand_dims","setflags(write=1)","xr.show_versions()"],"search_signals":["Error signature: ValueError","Traceback path: xarray/core/dataarray.py","Repository: pydata/xarray","Issue title: expand_dims() modifies numpy.ndarray.flags to write only, upon manually reverting this flag back, attempting to set a single inner value using .loc will instead set all of the inner array values.","Symbols: expand_dims, DataArray, .loc, __setitem__, Variable, set_dims, np.expand_dims, setflags(write=1), xr.show_versions().","numpy flags named in the report: C_CONTIGUOUS, F_CONTIGUOUS, OWNDATA, WRITEABLE, ALIGNED, WRITEBACKIFCOPY, UPDATEIFCOPY.","Files: xarray/core/dataarray.py, xarray/core/variable.py, xarray/core/indexing.py, xarray/core/dataset.py.","Verbatim error string: ValueError: assignment destination is read-only.","Reproduction: expanded_da = expanded_da.expand_dims({'z': 3}, -1) then expanded_da.loc[0, 0, 0] = 9.99.","Cross-reference: https://github.com/pydata/xarray/pull/2757.","Environment quoted in the report: xarray 0.12.1, pandas 0.24.2, numpy 1.16.2, Python 3.6.7, Darwin 18.2.0."],"match_summary":"Matches pydata/xarray work keyed on ValueError in expand_dims.","demonstrations":null},"evidence_search":{"guide_url":"https://agent-solution.dev/tasks/pydata-xarray-valueerror-expand-dims/llms.txt","method":"GET","url":"https://agent-solution.dev/tasks/pydata-xarray-valueerror-expand-dims/search","url_template":"https://agent-solution.dev/tasks/pydata-xarray-valueerror-expand-dims/search?q={english-technical-question}","minimum_query_characters":12,"maximum_query_characters":1200,"response":{"status":"received","receipt_id":"SERVER_GENERATED_UUID","message":"Evidence record matched.","evidence_record":{"title":"How do you fix xarray DataArray.expand_dims returning a read-only array so .loc updates only one value?","summary":"Matches pydata/xarray work keyed on ValueError in expand_dims.","task_statement":"expand_dims() modifies numpy.ndarray.flags to write only, upon manually reverting this flag back, attempting to set a single inner value using .loc will instead set all of the inner array values\nI am using the newly updated **expand_dims** API that was recently updated with this PR [https://github.com/pydata/xarray/pull/2757](https://github.com/pydata/xarray/pull/2757). However the flag setting behaviour can also be observed using the old API syntax.\r\n\r\n```python\r\n>>> expanded_da = xr.DataArray(np.random.rand(3,3), coords={'x': np.arange(3), 'y': np.arange(3)}, dims=('x', 'y')) # Create a 2D DataArray\r\n>>> expanded_da\r\n<xarray.DataArray (x: 3, y: 3)>\r\narray([[0.148579, 0.463005, 0.224993],\r\n       [0.633511, 0.056746, 0.28119 ],\r\n       [0.390596, 0.298519, 0.286853]])\r\nCoordinates:\r\n  * x        (x) int64 0 1 2\r\n  * y        (y) int64 0 1 2\r\n\r\n>>> expanded_da.data.flags # Check current state of numpy flags\r\n  C_CONTIGUOUS : True\r\n  F_CONTIGUOUS : False\r\n  OWNDATA : True\r\n  WRITEABLE : True\r\n  ALIGNED : True\r\n  WRITEBACKIFCOPY : False\r\n  UPDATEIFCOPY : False\r\n\r\n>>> expanded_da.loc[0, 0] = 2.22 # Set a single value before expanding\r\n>>> expanded_da # It works, the single value is set\r\n<xarray.DataArray (x: 3, y: 3)>\r\narray([[2.22    , 0.463005, 0.224993],\r\n       [0.633511, 0.056746, 0.28119 ],\r\n       [0.390596, 0.298519, 0.286853]])\r\nCoordinates:\r\n  * x        (x) int64 0 1 2\r\n  * y        (y) int64 0 1 2\r\n\r\n>>> expanded_da = expanded_da.expand_dims({'z': 3}, -1) # Add a new dimension 'z'\r\n>>> expanded_da\r\n<xarray.DataArray (x: 3, y: 3, z: 3)>\r\narray([[[2.22    , 2.22    , 2.22    ],\r\n        [0.463005, 0.463005, 0.463005],\r\n        [0.224993, 0.224993, 0.224993]],\r\n\r\n       [[0.633511, 0.633511, 0.633511],\r\n        [0.056746, 0.056746, 0.056746],\r\n        [0.28119 , 0.28119 , 0.28119 ]],\r\n\r\n       [[0.390596, 0.390596, 0.390596],\r\n        [0.298519, 0.298519, 0.298519],\r\n        [0.286853, 0.286853, 0.286853]]])\r\nCoordinates:\r\n  * x        (x) int64 0 1 2\r\n  * y        (y) int64 0 1 2\r\nDimensions without coordinates: z\r\n\r\n>>> expanded_da['z'] = np.arange(3) # Add new coordinates to the new dimension 'z'\r\n>>> expanded_da\r\n<xarray.DataArray (x: 3, y: 3, z: 3)>\r\narray([[[2.22    , 2.22    , 2.22    ],\r\n        [0.463005, 0.463005, 0.463005],\r\n        [0.224993, 0.224993, 0.224993]],\r\n\r\n       [[0.633511, 0.633511, 0.633511],\r\n        [0.056746, 0.056746, 0.056746],\r\n        [0.28119 , 0.28119 , 0.28119 ]],\r\n\r\n       [[0.390596, 0.390596, 0.390596],\r\n        [0.298519, 0.298519, 0.298519],\r\n        [0.286853, 0.286853, 0.286853]]])\r\nCoordinates:\r\n  * x        (x) int64 0 1 2\r\n  * y        (y) int64 0 1 2\r\n  * z        (z) int64 0 1 2\r\n\r\n>>> expanded_da.loc[0, 0, 0] = 9.99 # Attempt to set a single value, get 'read-only' error\r\nTraceback (most recent call last):\r\n  File \"<stdin>\", line 1, in <module>\r\n  File \"/Users/dhemming/.ve/unidata_notebooks/lib/python3.6/site-packages/xarray/core/dataarray.py\", line 113, in __setitem__\r\n    self.data_array[pos_indexers] = value\r\n  File \"/Users/dhemming/.ve/unidata_notebooks/lib/python3.6/site-packages/xarray/core/dataarray.py\", line 494, in __setitem__\r\n    self.variable[key] = value\r\n  File \"/Users/dhemming/.ve/unidata_notebooks/lib/python3.6/site-packages/xarray/core/variable.py\", line 714, in __setitem__\r\n    indexable[index_tuple] = value\r\n  File \"/Users/dhemming/.ve/unidata_notebooks/lib/python3.6/site-packages/xarray/core/indexing.py\", line 1174, in __setitem__\r\n    array[key] = value\r\nValueError: assignment destination is read-only\r\n\r\n>>> expanded_da.data.flags # Check flags on the DataArray, notice they have changed\r\n  C_CONTIGUOUS : False\r\n  F_CONTIGUOUS : False\r\n  OWNDATA : False\r\n  WRITEABLE : False\r\n  ALIGNED : True\r\n  WRITEBACKIFCOPY : False\r\n  UPDATEIFCOPY : False\r\n\r\n>>> expanded_da.data.setflags(write = 1) # Make array writeable again\r\n>>> expanded_da.data.flags\r\n  C_CONTIGUOUS : False\r\n  F_CONTIGUOUS : False\r\n  OWNDATA : False\r\n  WRITEABLE : True\r\n  ALIGNED : True\r\n  WRITEBACKIFCOPY : False\r\n  UPDATEIFCOPY : False\r\n\r\n>>> expanded_da.loc[0, 0, 0] # Check the value I want to overwrite\r\n<xarray.DataArray ()>\r\narray(2.22)\r\nCoordinates:\r\n    x        int64 0\r\n    y        int64 0\r\n    z        int64 0\r\n\r\n>>> expanded_da.loc[0, 0, 0] = 9.99 # Attempt to overwrite single value, instead it overwrites all values in the array located at [0, 0]\r\n>>> expanded_da\r\n<xarray.DataArray (x: 3, y: 3, z: 3)>\r\narray([[[9.99    , 9.99    , 9.99    ],\r\n        [0.463005, 0.463005, 0.463005],\r\n        [0.224993, 0.224993, 0.224993]],\r\n\r\n       [[0.633511, 0.633511, 0.633511],\r\n        [0.056746, 0.056746, 0.056746],\r\n        [0.28119 , 0.28119 , 0.28119 ]],\r\n\r\n       [[0.390596, 0.390596, 0.390596],\r\n        [0.298519, 0.298519, 0.298519],\r\n        [0.286853, 0.286853, 0.286853]]])\r\nCoordinates:\r\n  * x        (x) int64 0 1 2\r\n  * y        (y) int64 0 1 2\r\n  * z        (z) int64 0 1 2\r\n```\r\n#### Problem description\r\n\r\nWhen applying the operation '**expand_dims({'z': 3}, -1)**' on a DataArray the underlying Numpy array flags are changed. 'C_CONTIGUOUS' is set to False, and 'WRITEABLE' is set to False, and 'OWNDATA' is set to False.  Upon changing 'WRITEABLE' back to True, when I try to set a single value in the DataArray using the '.loc' operator it will instead set all the values in that selected inner array.\r\n\r\nI am new to Xarray so I can't be entirely sure if this expected behaviour.  Regardless I would expect that adding a new dimension to the array would not make that array 'read-only'.  I would also not expect the '.loc' method to work differently to how it would otherwise.\r\n\r\nIt's also not congruent with the Numpy '**expand_dims**' operation.  Because when I call the operation 'np.expand_dims(np_arr, axis=-1)' the 'C_CONTIGUOUS ' and 'WRITEABLE ' flags will not be modified.\r\n\r\n#### Expected Output\r\n\r\nHere is a similar flow of operations that demonstrates the behaviour I would expect from the DataArray after applying 'expand_dims':\r\n\r\n```python\r\n>>> non_expanded_da = xr.DataArray(np.random.rand(3,3,3), coords={'x': np.arange(3), 'y': np.arange(3)}, dims=('x', 'y', 'z')) # Create the new DataArray to be in the same state as I would expect it to be in after applying the operation 'expand_dims({'z': 3}, -1)'\r\n>>> non_expanded_da\r\n<xarray.DataArray (x: 3, y: 3, z: 3)>\r\narray([[[0.017221, 0.374267, 0.231979],\r\n        [0.678884, 0.512903, 0.737573],\r\n        [0.985872, 0.1373  , 0.4603  ]],\r\n\r\n       [[0.764227, 0.825059, 0.847694],\r\n        [0.482841, 0.708206, 0.486576],\r\n        [0.726265, 0.860627, 0.435101]],\r\n\r\n       [[0.117904, 0.40569 , 0.274288],\r\n        [0.079321, 0.647562, 0.847459],\r\n        [0.57494 , 0.578745, 0.125309]]])\r\nCoordinates:\r\n  * x        (x) int64 0 1 2\r\n  * y        (y) int64 0 1 2\r\nDimensions without coordinates: z\r\n\r\n>>> non_expanded_da.data.flags # Check flags\r\n  C_CONTIGUOUS : True\r\n  F_CONTIGUOUS : False\r\n  OWNDATA : True\r\n  WRITEABLE : True\r\n  ALIGNED : True\r\n  WRITEBACKIFCOPY : False\r\n  UPDATEIFCOPY : False\r\n\r\n>>> non_expanded_da['z'] = np.arange(3) # Set coordinate for dimension 'z'\r\n>>> non_expanded_da\r\n<xarray.DataArray (x: 3, y: 3, z: 3)>\r\narray([[[0.017221, 0.374267, 0.231979],\r\n        [0.678884, 0.512903, 0.737573],\r\n        [0.985872, 0.1373  , 0.4603  ]],\r\n\r\n       [[0.764227, 0.825059, 0.847694],\r\n        [0.482841, 0.708206, 0.486576],\r\n        [0.726265, 0.860627, 0.435101]],\r\n\r\n       [[0.117904, 0.40569 , 0.274288],\r\n        [0.079321, 0.647562, 0.847459],\r\n        [0.57494 , 0.578745, 0.125309]]])\r\nCoordinates:\r\n  * x        (x) int64 0 1 2\r\n  * y        (y) int64 0 1 2\r\n  * z        (z) int64 0 1 2\r\n\r\n>>> non_expanded_da.loc[0, 0, 0] = 2.22 # Set value using .loc method\r\n>>> non_expanded_da # The single value referenced is set which is what I expect to happen\r\n<xarray.DataArray (x: 3, y: 3, z: 3)>\r\narray([[[2.22    , 0.374267, 0.231979],\r\n        [0.678884, 0.512903, 0.737573],\r\n        [0.985872, 0.1373  , 0.4603  ]],\r\n\r\n       [[0.764227, 0.825059, 0.847694],\r\n        [0.482841, 0.708206, 0.486576],\r\n        [0.726265, 0.860627, 0.435101]],\r\n\r\n       [[0.117904, 0.40569 , 0.274288],\r\n        [0.079321, 0.647562, 0.847459],\r\n        [0.57494 , 0.578745, 0.125309]]])\r\nCoordinates:\r\n  * x        (x) int64 0 1 2\r\n  * y        (y) int64 0 1 2\r\n  * z        (z) int64 0 1 2\r\n```\r\n\r\n#### Output of ``xr.show_versions()``\r\n\r\n<details>\r\nINSTALLED VERSIONS\r\n------------------\r\ncommit: None\r\npython: 3.6.7 (default, Dec 29 2018, 12:05:36)\r\n[GCC 4.2.1 Compatible Apple LLVM 10.0.0 (clang-1000.11.45.5)]\r\npython-bits: 64\r\nOS: Darwin\r\nOS-release: 18.2.0\r\nmachine: x86_64\r\nprocessor: i386\r\nbyteorder: little\r\nLC_ALL: None\r\nLANG: en_AU.UTF-8\r\nLOCALE: en_AU.UTF-8\r\nlibhdf5: 1.10.2\r\nlibnetcdf: 4.4.1.1\r\n\r\nxarray: 0.12.1\r\npandas: 0.24.2\r\nnumpy: 1.16.2\r\nscipy: 1.2.1\r\nnetCDF4: 1.5.0\r\npydap: None\r\nh5netcdf: None\r\nh5py: None\r\nNio: None\r\nzarr: None\r\ncftime: 1.0.3.4\r\nnc_time_axis: None\r\nPseudonetCDF: None\r\nrasterio: None\r\ncfgrib: 0.9.6.1.post1\r\niris: None\r\nbottleneck: None\r\ndask: None\r\ndistributed: None\r\nmatplotlib: 3.0.3\r\ncartopy: 0.17.0\r\nseaborn: None\r\nsetuptools: 39.0.1\r\npip: 10.0.1\r\nconda: None\r\npytest: None\r\nIPython: None\r\nsphinx: None\r\n\r\n</details>","technical_objective":"Fix DataArray.expand_dims so the resulting object behaves like a normal, independently writable array. The deliverable covers both symptoms the reporter demonstrates: the expanded array must not come back with its underlying buffer marked non-writable, and assigning to a single element through label-based indexing must change only that element.","success_criteria":"after expanding a dimension, a single-element .loc assignment succeeds without a read-only error and leaves every other element untouched; the flags on the underlying array are consistent with an ordinary owned array; and existing expand_dims semantics (resulting dims, coords, order, and lazy/dask-backed cases) are preserved.","primary_terms":["ValueError","expand_dims","xarray/core/dataarray.py","pydata/xarray","DataArray",".loc","__setitem__","Variable","set_dims","np.expand_dims","setflags(write=1)","xr.show_versions()"],"search_signals":["Error signature: ValueError","Traceback path: xarray/core/dataarray.py","Repository: pydata/xarray","Issue title: expand_dims() modifies numpy.ndarray.flags to write only, upon manually reverting this flag back, attempting to set a single inner value using .loc will instead set all of the inner array values.","Symbols: expand_dims, DataArray, .loc, __setitem__, Variable, set_dims, np.expand_dims, setflags(write=1), xr.show_versions().","numpy flags named in the report: C_CONTIGUOUS, F_CONTIGUOUS, OWNDATA, WRITEABLE, ALIGNED, WRITEBACKIFCOPY, UPDATEIFCOPY.","Files: xarray/core/dataarray.py, xarray/core/variable.py, xarray/core/indexing.py, xarray/core/dataset.py.","Verbatim error string: ValueError: assignment destination is read-only.","Reproduction: expanded_da = expanded_da.expand_dims({'z': 3}, -1) then expanded_da.loc[0, 0, 0] = 9.99.","Cross-reference: https://github.com/pydata/xarray/pull/2757.","Environment quoted in the report: xarray 0.12.1, pandas 0.24.2, numpy 1.16.2, Python 3.6.7, Darwin 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