from __future__ import absolute_import, division, print_function import re import textwrap from distutils.version import LooseVersion from collections import Iterator import sys import traceback from contextlib import contextmanager import numpy as np import pandas as pd import pandas.util.testing as tm from pandas.api.types import is_categorical_dtype, is_scalar try: from pandas.api.types import is_datetime64tz_dtype except ImportError: # pandas < 0.19.2 from pandas.core.common import is_datetime64tz_dtype from ..core import get_deps from ..local import get_sync PANDAS_VERSION = LooseVersion(pd.__version__) def shard_df_on_index(df, divisions): """ Shard a DataFrame by ranges on its index Examples -------- >>> df = pd.DataFrame({'a': [0, 10, 20, 30, 40], 'b': [5, 4 ,3, 2, 1]}) >>> df a b 0 0 5 1 10 4 2 20 3 3 30 2 4 40 1 >>> shards = list(shard_df_on_index(df, [2, 4])) >>> shards[0] a b 0 0 5 1 10 4 >>> shards[1] a b 2 20 3 3 30 2 >>> shards[2] a b 4 40 1 >>> list(shard_df_on_index(df, []))[0] # empty case a b 0 0 5 1 10 4 2 20 3 3 30 2 4 40 1 """ if isinstance(divisions, Iterator): divisions = list(divisions) if not len(divisions): yield df else: divisions = np.array(divisions) df = df.sort_index() index = df.index if is_categorical_dtype(index): index = index.as_ordered() indices = index.searchsorted(divisions) yield df.iloc[:indices[0]] for i in range(len(indices) - 1): yield df.iloc[indices[i]: indices[i + 1]] yield df.iloc[indices[-1]:] _META_TYPES = "meta : pd.DataFrame, pd.Series, dict, iterable, tuple, optional" _META_DESCRIPTION = """\ An empty ``pd.DataFrame`` or ``pd.Series`` that matches the dtypes and column names of the output. This metadata is necessary for many algorithms in dask dataframe to work. For ease of use, some alternative inputs are also available. Instead of a ``DataFrame``, a ``dict`` of ``{name: dtype}`` or iterable of ``(name, dtype)`` can be provided. Instead of a series, a tuple of ``(name, dtype)`` can be used. If not provided, dask will try to infer the metadata. This may lead to unexpected results, so providing ``meta`` is recommended. For more information, see ``dask.dataframe.utils.make_meta``. """ def insert_meta_param_description(*args, **kwargs): """Replace `$META` in docstring with param description. If pad keyword is provided, will pad description by that number of spaces (default is 8).""" if not args: return lambda f: insert_meta_param_description(f, **kwargs) f = args[0] indent = " " * kwargs.get('pad', 8) body = textwrap.wrap(_META_DESCRIPTION, initial_indent=indent, subsequent_indent=indent, width=78) descr = '{0}\n{1}'.format(_META_TYPES, '\n'.join(body)) if f.__doc__: if '$META' in f.__doc__: f.__doc__ = f.__doc__.replace('$META', descr) else: # Put it at the end of the parameters section parameter_header = 'Parameters\n%s----------' % indent[4:] first, last = re.split('Parameters\\n[ ]*----------', f.__doc__) parameters, rest = last.split('\n\n', 1) f.__doc__ = '{0}{1}{2}\n{3}{4}\n\n{5}'.format(first, parameter_header, parameters, indent[4:], descr, rest) return f @contextmanager def raise_on_meta_error(funcname=None): """Reraise errors in this block to show metadata inference failure. Parameters ---------- funcname : str, optional If provided, will be added to the error message to indicate the name of the method that failed. """ try: yield except Exception as e: exc_type, exc_value, exc_traceback = sys.exc_info() tb = ''.join(traceback.format_tb(exc_traceback)) msg = ("Metadata inference failed{0}.\n\n" "Original error is below:\n" "------------------------\n" "{1}\n\n" "Traceback:\n" "---------\n" "{2}" ).format(" in `{0}`".format(funcname) if funcname else "", repr(e), tb) raise ValueError(msg) UNKNOWN_CATEGORIES = '__UNKNOWN_CATEGORIES__' def has_known_categories(x): """Returns whether the categories in `x` are known. Parameters ---------- x : Series or CategoricalIndex """ x = getattr(x, '_meta', x) if isinstance(x, pd.Series): return UNKNOWN_CATEGORIES not in x.cat.categories elif isinstance(x, pd.CategoricalIndex): return UNKNOWN_CATEGORIES not in x.categories raise TypeError("Expected Series or CategoricalIndex") def strip_unknown_categories(x): """Replace any unknown categoricals with empty categoricals. Useful for preventing ``UNKNOWN_CATEGORIES`` from leaking into results. """ if isinstance(x, (pd.Series, pd.DataFrame)): x = x.copy() if isinstance(x, pd.DataFrame): cat_mask = x.dtypes == 'category' if cat_mask.any(): cats = cat_mask[cat_mask].index for c in cats: if not has_known_categories(x[c]): x[c].cat.set_categories([], inplace=True) elif isinstance(x, pd.Series): if is_categorical_dtype(x.dtype) and not has_known_categories(x): x.cat.set_categories([], inplace=True) if (isinstance(x.index, pd.CategoricalIndex) and not has_known_categories(x.index)): x.index = x.index.set_categories([]) elif isinstance(x, pd.CategoricalIndex) and not has_known_categories(x): x = x.set_categories([]) return x def clear_known_categories(x, cols=None, index=True): """Set categories to be unknown. Parameters ---------- x : DataFrame, Series, Index cols : iterable, optional If x is a DataFrame, set only categoricals in these columns to unknown. By default, all categorical columns are set to unknown categoricals index : bool, optional If True and x is a Series or DataFrame, set the clear known categories in the index as well. """ if isinstance(x, (pd.Series, pd.DataFrame)): x = x.copy() if isinstance(x, pd.DataFrame): mask = x.dtypes == 'category' if cols is None: cols = mask[mask].index elif not mask.loc[cols].all(): raise ValueError("Not all columns are categoricals") for c in cols: x[c].cat.set_categories([UNKNOWN_CATEGORIES], inplace=True) elif isinstance(x, pd.Series): if is_categorical_dtype(x.dtype): x.cat.set_categories([UNKNOWN_CATEGORIES], inplace=True) if index and isinstance(x.index, pd.CategoricalIndex): x.index = x.index.set_categories([UNKNOWN_CATEGORIES]) elif isinstance(x, pd.CategoricalIndex): x = x.set_categories([UNKNOWN_CATEGORIES]) return x def _empty_series(name, dtype, index=None): if isinstance(dtype, str) and dtype == 'category': return pd.Series(pd.Categorical([UNKNOWN_CATEGORIES]), name=name, index=index).iloc[:0] return pd.Series([], dtype=dtype, name=name, index=index) def make_meta(x, index=None): """Create an empty pandas object containing the desired metadata. Parameters ---------- x : dict, tuple, list, pd.Series, pd.DataFrame, pd.Index, dtype, scalar To create a DataFrame, provide a `dict` mapping of `{name: dtype}`, or an iterable of `(name, dtype)` tuples. To create a `Series`, provide a tuple of `(name, dtype)`. If a pandas object, names, dtypes, and index should match the desired output. If a dtype or scalar, a scalar of the same dtype is returned. index : pd.Index, optional Any pandas index to use in the metadata. If none provided, a `RangeIndex` will be used. Examples -------- >>> make_meta([('a', 'i8'), ('b', 'O')]) Empty DataFrame Columns: [a, b] Index: [] >>> make_meta(('a', 'f8')) Series([], Name: a, dtype: float64) >>> make_meta('i8') 1 """ if hasattr(x, '_meta'): return x._meta if isinstance(x, (pd.Series, pd.DataFrame)): return x.iloc[0:0] elif isinstance(x, pd.Index): return x[0:0] index = index if index is None else index[0:0] if isinstance(x, dict): return pd.DataFrame({c: _empty_series(c, d, index=index) for (c, d) in x.items()}, index=index) if isinstance(x, tuple) and len(x) == 2: return _empty_series(x[0], x[1], index=index) elif isinstance(x, (list, tuple)): if not all(isinstance(i, tuple) and len(i) == 2 for i in x): raise ValueError("Expected iterable of tuples of (name, dtype), " "got {0}".format(x)) return pd.DataFrame({c: _empty_series(c, d, index=index) for (c, d) in x}, columns=[c for c, d in x], index=index) elif not hasattr(x, 'dtype') and x is not None: # could be a string, a dtype object, or a python type. Skip `None`, # because it is implictly converted to `dtype('f8')`, which we don't # want here. try: dtype = np.dtype(x) return _scalar_from_dtype(dtype) except: # Continue on to next check pass if is_scalar(x): return _nonempty_scalar(x) raise TypeError("Don't know how to create metadata from {0}".format(x)) if PANDAS_VERSION >= "0.20.0": _numeric_index_types = (pd.Int64Index, pd.Float64Index, pd.UInt64Index) else: _numeric_index_types = (pd.Int64Index, pd.Float64Index) def _nonempty_index(idx): typ = type(idx) if typ is pd.RangeIndex: return pd.RangeIndex(2, name=idx.name) elif typ in _numeric_index_types: return typ([1, 2], name=idx.name) elif typ is pd.Index: return pd.Index(['a', 'b'], name=idx.name) elif typ is pd.DatetimeIndex: start = '1970-01-01' # Need a non-monotonic decreasing index to avoid issues with # partial string indexing see https://github.com/dask/dask/issues/2389 # and https://github.com/pandas-dev/pandas/issues/16515 # This doesn't mean `_meta_nonempty` should ever rely on # `self.monotonic_increasing` or `self.monotonic_decreasing` data = [start, '1970-01-02'] if idx.freq is None else None return pd.DatetimeIndex(data, start=start, periods=2, freq=idx.freq, tz=idx.tz, name=idx.name) elif typ is pd.PeriodIndex: return pd.PeriodIndex(start='1970-01-01', periods=2, freq=idx.freq, name=idx.name) elif typ is pd.TimedeltaIndex: start = np.timedelta64(1, 'D') data = [start, start] if idx.freq is None else None return pd.TimedeltaIndex(data, start=start, periods=2, freq=idx.freq, name=idx.name) elif typ is pd.CategoricalIndex: if len(idx.categories): data = [idx.categories[0]] * 2 cats = idx.categories else: data = _nonempty_index(idx.categories) cats = None return pd.CategoricalIndex(data, categories=cats, ordered=idx.ordered, name=idx.name) elif typ is pd.MultiIndex: levels = [_nonempty_index(i) for i in idx.levels] labels = [[0, 0] for i in idx.levels] return pd.MultiIndex(levels=levels, labels=labels, names=idx.names) raise TypeError("Don't know how to handle index of " "type {0}".format(type(idx).__name__)) _simple_fake_mapping = { 'b': np.bool_(True), 'V': np.void(b' '), 'M': np.datetime64('1970-01-01'), 'm': np.timedelta64(1), 'S': np.str_('foo'), 'a': np.str_('foo'), 'U': np.unicode_('foo'), 'O': 'foo' } def _scalar_from_dtype(dtype): if dtype.kind in ('i', 'f', 'u'): return dtype.type(1) elif dtype.kind == 'c': return dtype.type(complex(1, 0)) elif dtype.kind in _simple_fake_mapping: o = _simple_fake_mapping[dtype.kind] return o.astype(dtype) if dtype.kind in ('m', 'M') else o else: raise TypeError("Can't handle dtype: {0}".format(dtype)) def _nonempty_scalar(x): if isinstance(x, (pd.Timestamp, pd.Timedelta, pd.Period)): return x elif np.isscalar(x): dtype = x.dtype if hasattr(x, 'dtype') else np.dtype(type(x)) return _scalar_from_dtype(dtype) else: raise TypeError("Can't handle meta of type " "'{0}'".format(type(x).__name__)) def _nonempty_series(s, idx): dtype = s.dtype if is_datetime64tz_dtype(dtype): entry = pd.Timestamp('1970-01-01', tz=dtype.tz) data = [entry, entry] elif is_categorical_dtype(dtype): if len(s.cat.categories): data = [s.cat.categories[0]] * 2 cats = s.cat.categories else: data = _nonempty_index(s.cat.categories) cats = None data = pd.Categorical(data, categories=cats, ordered=s.cat.ordered) else: entry = _scalar_from_dtype(dtype) data = np.array([entry, entry], dtype=dtype) return pd.Series(data, name=s.name, index=idx) def meta_nonempty(x): """Create a nonempty pandas object from the given metadata. Returns a pandas DataFrame, Series, or Index that contains two rows of fake data. """ if isinstance(x, pd.Index): return _nonempty_index(x) elif isinstance(x, pd.Series): idx = _nonempty_index(x.index) return _nonempty_series(x, idx) elif isinstance(x, pd.DataFrame): idx = _nonempty_index(x.index) data = {i: _nonempty_series(x.iloc[:, i], idx) for i, c in enumerate(x.columns)} res = pd.DataFrame(data, index=idx, columns=np.arange(len(x.columns))) res.columns = x.columns return res elif is_scalar(x): return _nonempty_scalar(x) else: raise TypeError("Expected Index, Series, DataFrame, or scalar, " "got {0}".format(type(x).__name__)) ############################################################### # Testing ############################################################### def _check_dask(dsk, check_names=True, check_dtypes=True, result=None): import dask.dataframe as dd if hasattr(dsk, 'dask'): if result is None: result = dsk.compute(get=get_sync) if isinstance(dsk, dd.Index): assert isinstance(result, pd.Index), type(result) assert isinstance(dsk._meta, pd.Index), type(dsk._meta) if check_names: assert dsk.name == result.name assert dsk._meta.name == result.name if isinstance(result, pd.MultiIndex): assert result.names == dsk._meta.names if check_dtypes: assert_dask_dtypes(dsk, result) elif isinstance(dsk, dd.Series): assert isinstance(result, pd.Series), type(result) assert isinstance(dsk._meta, pd.Series), type(dsk._meta) if check_names: assert dsk.name == result.name, (dsk.name, result.name) assert dsk._meta.name == result.name if check_dtypes: assert_dask_dtypes(dsk, result) _check_dask(dsk.index, check_names=check_names, check_dtypes=check_dtypes, result=result.index) elif isinstance(dsk, dd.DataFrame): assert isinstance(result, pd.DataFrame), type(result) assert isinstance(dsk.columns, pd.Index), type(dsk.columns) assert isinstance(dsk._meta, pd.DataFrame), type(dsk._meta) if check_names: tm.assert_index_equal(dsk.columns, result.columns) tm.assert_index_equal(dsk._meta.columns, result.columns) if check_dtypes: assert_dask_dtypes(dsk, result) _check_dask(dsk.index, check_names=check_names, check_dtypes=check_dtypes, result=result.index) elif isinstance(dsk, dd.core.Scalar): assert (np.isscalar(result) or isinstance(result, (pd.Timestamp, pd.Timedelta))) if check_dtypes: assert_dask_dtypes(dsk, result) else: msg = 'Unsupported dask instance {0} found'.format(type(dsk)) raise AssertionError(msg) return result return dsk def _maybe_sort(a): # sort by value, then index try: if isinstance(a, pd.DataFrame): a = a.sort_values(by=a.columns.tolist()) else: a = a.sort_values() except (TypeError, IndexError, ValueError): pass return a.sort_index() def assert_eq(a, b, check_names=True, check_dtypes=True, check_divisions=True, check_index=True, **kwargs): if check_divisions: assert_divisions(a) assert_divisions(b) if hasattr(a, 'divisions') and hasattr(b, 'divisions'): at = type(np.asarray(a.divisions).tolist()[0]) # numpy to python bt = type(np.asarray(b.divisions).tolist()[0]) # scalar conversion assert at == bt, (at, bt) assert_sane_keynames(a) assert_sane_keynames(b) a = _check_dask(a, check_names=check_names, check_dtypes=check_dtypes) b = _check_dask(b, check_names=check_names, check_dtypes=check_dtypes) if not check_index: a = a.reset_index(drop=True) b = b.reset_index(drop=True) if isinstance(a, pd.DataFrame): a = _maybe_sort(a) b = _maybe_sort(b) tm.assert_frame_equal(a, b, **kwargs) elif isinstance(a, pd.Series): a = _maybe_sort(a) b = _maybe_sort(b) tm.assert_series_equal(a, b, check_names=check_names, **kwargs) elif isinstance(a, pd.Index): tm.assert_index_equal(a, b, **kwargs) else: if a == b: return True else: if np.isnan(a): assert np.isnan(b) else: assert np.allclose(a, b) return True def assert_dask_graph(dask, label): if hasattr(dask, 'dask'): dask = dask.dask assert isinstance(dask, dict) for k in dask: if isinstance(k, tuple): k = k[0] if k.startswith(label): return True else: msg = "given dask graph doesn't contan label: {0}" raise AssertionError(msg.format(label)) def assert_divisions(ddf): if not hasattr(ddf, 'divisions'): return if not hasattr(ddf, 'index'): return if not ddf.known_divisions: return index = lambda x: x if isinstance(x, pd.Index) else x.index results = get_sync(ddf.dask, ddf._keys()) for i, df in enumerate(results[:-1]): if len(df): assert index(df).min() >= ddf.divisions[i] assert index(df).max() < ddf.divisions[i + 1] if len(results[-1]): assert index(results[-1]).min() >= ddf.divisions[-2] assert index(results[-1]).max() <= ddf.divisions[-1] def assert_sane_keynames(ddf): if not hasattr(ddf, 'dask'): return for k in ddf.dask.keys(): while isinstance(k, tuple): k = k[0] assert isinstance(k, (str, bytes)) assert len(k) < 100 assert ' ' not in k if sys.version_info[0] >= 3: assert k.split('-')[0].isidentifier() def assert_dask_dtypes(ddf, res, numeric_equal=True): """Check that the dask metadata matches the result. If `numeric_equal`, integer and floating dtypes compare equal. This is useful due to the implicit conversion of integer to floating upon encountering missingness, which is hard to infer statically.""" eq_types = {'O', 'S', 'U', 'a'} # treat object and strings alike if numeric_equal: eq_types.update(('i', 'f')) if isinstance(res, pd.DataFrame): for col, a, b in pd.concat([ddf._meta.dtypes, res.dtypes], axis=1).itertuples(): assert (a.kind in eq_types and b.kind in eq_types) or (a == b) elif isinstance(res, (pd.Series, pd.Index)): a = ddf._meta.dtype b = res.dtype assert (a.kind in eq_types and b.kind in eq_types) or (a == b) else: if hasattr(ddf._meta, 'dtype'): a = ddf._meta.dtype if not hasattr(res, 'dtype'): assert np.isscalar(res) b = np.dtype(type(res)) else: b = res.dtype assert (a.kind in eq_types and b.kind in eq_types) or (a == b) else: assert type(ddf._meta) == type(res) def assert_max_deps(x, n, eq=True): dependencies, dependents = get_deps(x.dask) if eq: assert max(map(len, dependencies.values())) == n else: assert max(map(len, dependencies.values())) <= n