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DOC: add example for sparse.density and sparse.coo #51909

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Mar 16, 2023
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DOC: add example for sparse.density and sparse.coo #51909

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DOC: add example for sparse.density and sparse.coo
Moisan Mar 11, 2023
9bbeabb
fixup! DOC: add example for sparse.density and sparse.coo
Moisan Mar 15, 2023
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2 changes: 0 additions & 2 deletions ci/code_checks.sh
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Original file line number Diff line number Diff line change
Expand Up @@ -547,8 +547,6 @@ if [[ -z "$CHECK" || "$CHECK" == "docstrings" ]]; then
pandas.DataFrame.last_valid_index \
pandas.DataFrame.attrs \
pandas.DataFrame.plot \
pandas.DataFrame.sparse.density \
pandas.DataFrame.sparse.to_coo \
pandas.DataFrame.to_gbq \
pandas.DataFrame.style \
pandas.DataFrame.__dataframe__
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18 changes: 18 additions & 0 deletions pandas/core/arrays/sparse/accessor.py
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Expand Up @@ -329,6 +329,18 @@ def to_coo(self):
e.g. If the dtypes are float16 and float32, dtype will be upcast to
float32. By numpy.find_common_type convention, mixing int64 and
and uint64 will result in a float64 dtype.

Examples
--------
>>> df = pd.DataFrame({"A": pd.arrays.SparseArray([0, 1, 0, 1])})
>>> df.sparse.to_coo()
<4x1 sparse matrix of type '<class 'numpy.int64'>'
with 2 stored elements in COOrdinate format>
>>> sparse_array = pd.arrays.SparseArray([0, 1.234, 0, 8.32], fill_value=0)
>>> df = pd.DataFrame({"A": sparse_array})
>>> df.sparse.to_coo()
<4x1 sparse matrix of type '<class 'numpy.float64'>'
with 2 stored elements in COOrdinate format>
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thanks for working on this - does fill_value do anything here?

I'd suggest either:

  • writing an example where fill_value has an effect
  • just keeping the example above

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to_coo() requires the fill_value to be zero, but when using floats, it is np.nan by default:

>>> df = pd.DataFrame({"A": pd.arrays.SparseArray([0, 1.234, 0, 8.32])})
>>> df.sparse.to_coo()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/thierrymoisan/dev/pandas/pandas/core/arrays/sparse/accessor.py", line 344, in to_coo
    raise ValueError("fill value must be 0 when converting to COO matrix")
ValueError: fill value must be 0 when converting to COO matrix

So I believe fill_value does have an effect in this example.

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@MarcoGorelli MarcoGorelli Mar 15, 2023 •
edited
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thanks for explaining - to be honest I'd leave this second example out, I'm not sure what it adds (either that, or add a sentence before the example explaining what it does)

"""
import_optional_dependency("scipy")
from scipy.sparse import coo_matrix
Expand Down Expand Up @@ -357,6 +369,12 @@ def to_coo(self):
def density(self) -> float:
"""
Ratio of non-sparse points to total (dense) data points.

Examples
--------
>>> df = pd.DataFrame({"A": pd.arrays.SparseArray([0, 1, 0, 1])})
>>> df.sparse.density
0.5
"""
tmp = np.mean([column.array.density for _, column in self._parent.items()])
return tmp
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