def na_op(x, y):
try:
result = op(x, y)
except TypeError:
if isinstance(y, list):
y = construct_1d_object_array_from_listlike(y)
if isinstance(y, (np.ndarray, ABCSeries)):
if (is_bool_dtype(x.dtype) and is_bool_dtype(y.dtype)):
result = op(x, y) # when would this be hit?
else:
x = _ensure_object(x)
y = _ensure_object(y)
result = lib.vec_binop(x, y, op)
else:
# let null fall thru
if not isna(y):
y = bool(y)
try:
result = lib.scalar_binop(x, y, op)
except:
msg = ("cannot compare a dtyped [{dtype}] array "
"with a scalar of type [{type}]").format(
dtype=x.dtype, type=type(y).__name__)
raise TypeError(msg)
return result
def na_op(x, y):
try:
result = op(x, y)
except TypeError:
if isinstance(y, list):
y = construct_1d_object_array_from_listlike(y)
if isinstance(y, (np.ndarray, ABCSeries)):
if (is_bool_dtype(x.dtype) and is_bool_dtype(y.dtype)):
result = op(x, y) # when would this be hit?
else:
x = _ensure_object(x)
y = _ensure_object(y)
result = lib.vec_binop(x, y, op)
else:
# let null fall thru
if not isna(y):
y = bool(y)
try:
result = lib.scalar_binop(x, y, op)
except:
msg = ("cannot compare a dtyped [{dtype}] array "
"with a scalar of type [{type}]"
).format(dtype=x.dtype, type=type(y).__name__)
raise TypeError(msg)
return result
def _convert_listlike(arg, unit='ns', box=True, errors='raise', name=None):
"""Convert a list of objects to a timedelta index object."""
if isinstance(arg, (list, tuple)) or not hasattr(arg, 'dtype'):
arg = np.array(list(arg), dtype='O')
# these are shortcut-able
if is_timedelta64_dtype(arg):
value = arg.astype('timedelta64[ns]')
elif is_integer_dtype(arg):
value = arg.astype('timedelta64[{0}]'.format(
unit)).astype('timedelta64[ns]', copy=False)
else:
try:
value = tslib.array_to_timedelta64(_ensure_object(arg),
unit=unit, errors=errors)
value = value.astype('timedelta64[ns]', copy=False)
except ValueError:
if errors == 'ignore':
return arg
else:
# This else-block accounts for the cases when errors='raise'
# and errors='coerce'. If errors == 'raise', these errors
# should be raised. If errors == 'coerce', we shouldn't
# expect any errors to be raised, since all parsing errors
# cause coercion to pd.NaT. However, if an error / bug is
# introduced that causes an Exception to be raised, we would
# like to surface it.
raise
if box:
from pandas import TimedeltaIndex
value = TimedeltaIndex(value, unit='ns', name=name)
return value
def _convert_listlike(arg, unit='ns', box=True, errors='raise', name=None):
"""Convert a list of objects to a timedelta index object."""
if isinstance(arg, (list, tuple)) or not hasattr(arg, 'dtype'):
arg = np.array(list(arg), dtype='O')
# these are shortcut-able
if is_timedelta64_dtype(arg):
value = arg.astype('timedelta64[ns]')
elif is_integer_dtype(arg):
value = arg.astype('timedelta64[{unit}]'.format(unit=unit)).astype(
'timedelta64[ns]', copy=False)
else:
try:
value = tslib.array_to_timedelta64(_ensure_object(arg),
unit=unit,
errors=errors)
value = value.astype('timedelta64[ns]', copy=False)
except ValueError:
if errors == 'ignore':
return arg
else:
# This else-block accounts for the cases when errors='raise'
# and errors='coerce'. If errors == 'raise', these errors
# should be raised. If errors == 'coerce', we shouldn't
# expect any errors to be raised, since all parsing errors
# cause coercion to pd.NaT. However, if an error / bug is
# introduced that causes an Exception to be raised, we would
# like to surface it.
raise
if box:
from pandas import TimedeltaIndex
value = TimedeltaIndex(value, unit='ns', name=name)
return value
def _convert_listlike(arg, format):
if isinstance(arg, (list, tuple)):
arg = np.array(arg, dtype='O')
elif getattr(arg, 'ndim', 1) > 1:
raise TypeError('arg must be a string, datetime, list, tuple, '
'1-d array, or Series')
arg = _ensure_object(arg)
if infer_time_format and format is None:
format = _guess_time_format_for_array(arg)
times = []
if format is not None:
for element in arg:
try:
times.append(datetime.strptime(element, format).time())
except (ValueError, TypeError):
if errors == 'raise':
msg = ("Cannot convert {element} to a time with given "
"format {format}").format(element=element,
format=format)
raise ValueError(msg)
elif errors == 'ignore':
return arg
else:
times.append(None)
else:
formats = _time_formats[:]
format_found = False
for element in arg:
time_object = None
for time_format in formats:
try:
time_object = datetime.strptime(element,
time_format).time()
if not format_found:
# Put the found format in front
fmt = formats.pop(formats.index(time_format))
formats.insert(0, fmt)
format_found = True
break
except (ValueError, TypeError):
continue
if time_object is not None:
times.append(time_object)
elif errors == 'raise':
raise ValueError("Cannot convert arg {arg} to "
"a time".format(arg=arg))
elif errors == 'ignore':
return arg
else:
times.append(None)
return times
def _convert_string_array(dt, encoding, itemsize=None):
from pandas._libs import lib
from pandas.core.dtypes.common import _ensure_object
if dt.dtype.name == 'object':
# encode if needed
if encoding is not None and len(dt):
dt = pd.Series(dt.ravel()).str.encode(encoding).values.reshape(
dt.shape)
# create the sized dtype
if itemsize is None:
itemsize = lib.max_len_string_array(_ensure_object(dt.ravel()))
dt = np.asarray(dt, dtype="S%d" % itemsize)
return dt
else:
return dt
def __new__(cls,
data=None,
ordinal=None,
freq=None,
start=None,
end=None,
periods=None,
copy=False,
name=None,
tz=None,
dtype=None,
**kwargs):
if periods is not None:
if is_float(periods):
periods = int(periods)
elif not is_integer(periods):
msg = 'periods must be a number, got {periods}'
raise TypeError(msg.format(periods=periods))
if name is None and hasattr(data, 'name'):
name = data.name
if dtype is not None:
dtype = pandas_dtype(dtype)
if not is_period_dtype(dtype):
raise ValueError('dtype must be PeriodDtype')
if freq is None:
freq = dtype.freq
elif freq != dtype.freq:
msg = 'specified freq and dtype are different'
raise IncompatibleFrequency(msg)
# coerce freq to freq object, otherwise it can be coerced elementwise
# which is slow
if freq:
freq = Period._maybe_convert_freq(freq)
if data is None:
if ordinal is not None:
data = np.asarray(ordinal, dtype=np.int64)
else:
data, freq = cls._generate_range(start, end, periods, freq,
kwargs)
return cls._from_ordinals(data, name=name, freq=freq)
if isinstance(data, PeriodIndex):
if freq is None or freq == data.freq: # no freq change
freq = data.freq
data = data._values
else:
base1, _ = _gfc(data.freq)
base2, _ = _gfc(freq)
data = period.period_asfreq_arr(data._values, base1, base2, 1)
return cls._simple_new(data, name=name, freq=freq)
# not array / index
if not isinstance(
data, (np.ndarray, PeriodIndex, DatetimeIndex, Int64Index)):
if is_scalar(data) or isinstance(data, Period):
cls._scalar_data_error(data)
# other iterable of some kind
if not isinstance(data, (list, tuple)):
data = list(data)
data = np.asarray(data)
# datetime other than period
if is_datetime64_dtype(data.dtype):
data = dt64arr_to_periodarr(data, freq, tz)
return cls._from_ordinals(data, name=name, freq=freq)
# check not floats
if infer_dtype(data) == 'floating' and len(data) > 0:
raise TypeError("PeriodIndex does not allow "
"floating point in construction")
# anything else, likely an array of strings or periods
data = _ensure_object(data)
freq = freq or period.extract_freq(data)
data = period.extract_ordinals(data, freq)
return cls._from_ordinals(data, name=name, freq=freq)
def _convert_listlike(arg, box, format, name=None, tz=tz):
if isinstance(arg, (list, tuple)):
arg = np.array(arg, dtype='O')
# these are shortcutable
if is_datetime64tz_dtype(arg):
if not isinstance(arg, DatetimeIndex):
return DatetimeIndex(arg, tz=tz, name=name)
if utc:
arg = arg.tz_convert(None).tz_localize('UTC')
return arg
elif is_datetime64_ns_dtype(arg):
if box and not isinstance(arg, DatetimeIndex):
try:
return DatetimeIndex(arg, tz=tz, name=name)
except ValueError:
pass
return arg
elif unit is not None:
if format is not None:
raise ValueError("cannot specify both format and unit")
arg = getattr(arg, 'values', arg)
result = tslib.array_with_unit_to_datetime(arg, unit,
errors=errors)
if box:
if errors == 'ignore':
from pandas import Index
return Index(result)
return DatetimeIndex(result, tz=tz, name=name)
return result
elif getattr(arg, 'ndim', 1) > 1:
raise TypeError('arg must be a string, datetime, list, tuple, '
'1-d array, or Series')
arg = _ensure_object(arg)
require_iso8601 = False
if infer_datetime_format and format is None:
format = _guess_datetime_format_for_array(arg, dayfirst=dayfirst)
if format is not None:
# There is a special fast-path for iso8601 formatted
# datetime strings, so in those cases don't use the inferred
# format because this path makes process slower in this
# special case
format_is_iso8601 = _format_is_iso(format)
if format_is_iso8601:
require_iso8601 = not infer_datetime_format
format = None
try:
result = None
if format is not None:
# shortcut formatting here
if format == '%Y%m%d':
try:
result = _attempt_YYYYMMDD(arg, errors=errors)
except:
raise ValueError("cannot convert the input to "
"'%Y%m%d' date format")
# fallback
if result is None:
try:
result = array_strptime(arg, format, exact=exact,
errors=errors)
except tslib.OutOfBoundsDatetime:
if errors == 'raise':
raise
result = arg
except ValueError:
# if format was inferred, try falling back
# to array_to_datetime - terminate here
# for specified formats
if not infer_datetime_format:
if errors == 'raise':
raise
result = arg
if result is None and (format is None or infer_datetime_format):
result = tslib.array_to_datetime(
arg,
errors=errors,
utc=utc,
dayfirst=dayfirst,
yearfirst=yearfirst,
require_iso8601=require_iso8601
)
if is_datetime64_dtype(result) and box:
result = DatetimeIndex(result, tz=tz, name=name)
return result
except ValueError as e:
try:
values, tz = conversion.datetime_to_datetime64(arg)
return DatetimeIndex._simple_new(values, name=name, tz=tz)
except (ValueError, TypeError):
raise e
def __new__(cls, data=None, ordinal=None, freq=None, start=None, end=None,
periods=None, copy=False, name=None, tz=None, dtype=None,
**kwargs):
if periods is not None:
if is_float(periods):
periods = int(periods)
elif not is_integer(periods):
msg = 'periods must be a number, got {periods}'
raise TypeError(msg.format(periods=periods))
if name is None and hasattr(data, 'name'):
name = data.name
if dtype is not None:
dtype = pandas_dtype(dtype)
if not is_period_dtype(dtype):
raise ValueError('dtype must be PeriodDtype')
if freq is None:
freq = dtype.freq
elif freq != dtype.freq:
msg = 'specified freq and dtype are different'
raise IncompatibleFrequency(msg)
# coerce freq to freq object, otherwise it can be coerced elementwise
# which is slow
if freq:
freq = Period._maybe_convert_freq(freq)
if data is None:
if ordinal is not None:
data = np.asarray(ordinal, dtype=np.int64)
else:
data, freq = cls._generate_range(start, end, periods,
freq, kwargs)
return cls._from_ordinals(data, name=name, freq=freq)
if isinstance(data, PeriodIndex):
if freq is None or freq == data.freq: # no freq change
freq = data.freq
data = data._values
else:
base1, _ = _gfc(data.freq)
base2, _ = _gfc(freq)
data = period.period_asfreq_arr(data._values,
base1, base2, 1)
return cls._simple_new(data, name=name, freq=freq)
# not array / index
if not isinstance(data, (np.ndarray, PeriodIndex,
DatetimeIndex, Int64Index)):
if is_scalar(data) or isinstance(data, Period):
cls._scalar_data_error(data)
# other iterable of some kind
if not isinstance(data, (list, tuple)):
data = list(data)
data = np.asarray(data)
# datetime other than period
if is_datetime64_dtype(data.dtype):
data = dt64arr_to_periodarr(data, freq, tz)
return cls._from_ordinals(data, name=name, freq=freq)
# check not floats
if infer_dtype(data) == 'floating' and len(data) > 0:
raise TypeError("PeriodIndex does not allow "
"floating point in construction")
# anything else, likely an array of strings or periods
data = _ensure_object(data)
freq = freq or period.extract_freq(data)
data = period.extract_ordinals(data, freq)
return cls._from_ordinals(data, name=name, freq=freq)
def to_numeric(arg, errors='raise', downcast=None):
"""
Convert argument to a numeric type.
The default return dtype is `float64` or `int64`
depending on the data supplied. Use the `downcast` parameter
to obtain other dtypes.
Parameters
----------
arg : list, tuple, 1-d array, or Series
errors : {'ignore', 'raise', 'coerce'}, default 'raise'
- If 'raise', then invalid parsing will raise an exception
- If 'coerce', then invalid parsing will be set as NaN
- If 'ignore', then invalid parsing will return the input
downcast : {'integer', 'signed', 'unsigned', 'float'} , default None
If not None, and if the data has been successfully cast to a
numerical dtype (or if the data was numeric to begin with),
downcast that resulting data to the smallest numerical dtype
possible according to the following rules:
- 'integer' or 'signed': smallest signed int dtype (min.: np.int8)
- 'unsigned': smallest unsigned int dtype (min.: np.uint8)
- 'float': smallest float dtype (min.: np.float32)
As this behaviour is separate from the core conversion to
numeric values, any errors raised during the downcasting
will be surfaced regardless of the value of the 'errors' input.
In addition, downcasting will only occur if the size
of the resulting data's dtype is strictly larger than
the dtype it is to be cast to, so if none of the dtypes
checked satisfy that specification, no downcasting will be
performed on the data.
.. versionadded:: 0.19.0
Returns
-------
ret : numeric if parsing succeeded.
Return type depends on input. Series if Series, otherwise ndarray
Examples
--------
Take separate series and convert to numeric, coercing when told to
>>> s = pd.Series(['1.0', '2', -3])
>>> pd.to_numeric(s)
0 1.0
1 2.0
2 -3.0
dtype: float64
>>> pd.to_numeric(s, downcast='float')
0 1.0
1 2.0
2 -3.0
dtype: float32
>>> pd.to_numeric(s, downcast='signed')
0 1
1 2
2 -3
dtype: int8
>>> s = pd.Series(['apple', '1.0', '2', -3])
>>> pd.to_numeric(s, errors='ignore')
0 apple
1 1.0
2 2
3 -3
dtype: object
>>> pd.to_numeric(s, errors='coerce')
0 NaN
1 1.0
2 2.0
3 -3.0
dtype: float64
See also
--------
pandas.DataFrame.astype : Cast argument to a specified dtype.
pandas.to_datetime : Convert argument to datetime.
pandas.to_timedelta : Convert argument to timedelta.
numpy.ndarray.astype : Cast a numpy array to a specified type.
"""
if downcast not in (None, 'integer', 'signed', 'unsigned', 'float'):
raise ValueError('invalid downcasting method provided')
is_series = False
is_index = False
is_scalars = False
if isinstance(arg, ABCSeries):
is_series = True
values = arg.values
elif isinstance(arg, ABCIndexClass):
is_index = True
values = arg.asi8
if values is None:
values = arg.values
elif isinstance(arg, (list, tuple)):
values = np.array(arg, dtype='O')
elif is_scalar(arg):
if is_decimal(arg):
return float(arg)
if is_number(arg):
return arg
is_scalars = True
values = np.array([arg], dtype='O')
elif getattr(arg, 'ndim', 1) > 1:
raise TypeError('arg must be a list, tuple, 1-d array, or Series')
else:
values = arg
try:
if is_numeric_dtype(values):
pass
elif is_datetime_or_timedelta_dtype(values):
values = values.astype(np.int64)
else:
values = _ensure_object(values)
coerce_numeric = False if errors in ('ignore', 'raise') else True
values = lib.maybe_convert_numeric(values,
set(),
coerce_numeric=coerce_numeric)
except Exception:
if errors == 'raise':
raise
# attempt downcast only if the data has been successfully converted
# to a numerical dtype and if a downcast method has been specified
if downcast is not None and is_numeric_dtype(values):
typecodes = None
if downcast in ('integer', 'signed'):
typecodes = np.typecodes['Integer']
elif downcast == 'unsigned' and np.min(values) >= 0:
typecodes = np.typecodes['UnsignedInteger']
elif downcast == 'float':
typecodes = np.typecodes['Float']
# pandas support goes only to np.float32,
# as float dtypes smaller than that are
# extremely rare and not well supported
float_32_char = np.dtype(np.float32).char
float_32_ind = typecodes.index(float_32_char)
typecodes = typecodes[float_32_ind:]
if typecodes is not None:
# from smallest to largest
for dtype in typecodes:
if np.dtype(dtype).itemsize <= values.dtype.itemsize:
values = maybe_downcast_to_dtype(values, dtype)
# successful conversion
if values.dtype == dtype:
break
if is_series:
return pd.Series(values, index=arg.index, name=arg.name)
elif is_index:
# because we want to coerce to numeric if possible,
# do not use _shallow_copy_with_infer
return pd.Index(values, name=arg.name)
elif is_scalars:
return values[0]
else:
return values
def _convert_listlike_datetimes(arg,
box,
format,
name=None,
tz=None,
unit=None,
errors=None,
infer_datetime_format=None,
dayfirst=None,
yearfirst=None,
exact=None):
"""
Helper function for to_datetime. Performs the conversions of 1D listlike
of dates
Parameters
----------
arg : list, tuple, ndarray, Series, Index
date to be parced
box : boolean
True boxes result as an Index-like, False returns an ndarray
name : object
None or string for the Index name
tz : object
None or 'utc'
unit : string
None or string of the frequency of the passed data
errors : string
error handing behaviors from to_datetime, 'raise', 'coerce', 'ignore'
infer_datetime_format : boolean
inferring format behavior from to_datetime
dayfirst : boolean
dayfirst parsing behavior from to_datetime
yearfirst : boolean
yearfirst parsing behavior from to_datetime
exact : boolean
exact format matching behavior from to_datetime
Returns
-------
ndarray of parsed dates
Returns:
- Index-like if box=True
- ndarray of Timestamps if box=False
"""
from pandas import DatetimeIndex
if isinstance(arg, (list, tuple)):
arg = np.array(arg, dtype='O')
# these are shortcutable
if is_datetime64tz_dtype(arg):
if not isinstance(arg, DatetimeIndex):
return DatetimeIndex(arg, tz=tz, name=name)
if tz == 'utc':
arg = arg.tz_convert(None).tz_localize(tz)
return arg
elif is_datetime64_ns_dtype(arg):
if box and not isinstance(arg, DatetimeIndex):
try:
return DatetimeIndex(arg, tz=tz, name=name)
except ValueError:
pass
return arg
elif unit is not None:
if format is not None:
raise ValueError("cannot specify both format and unit")
arg = getattr(arg, 'values', arg)
result = tslib.array_with_unit_to_datetime(arg, unit, errors=errors)
if box:
if errors == 'ignore':
from pandas import Index
return Index(result)
return DatetimeIndex(result, tz=tz, name=name)
return result
elif getattr(arg, 'ndim', 1) > 1:
raise TypeError('arg must be a string, datetime, list, tuple, '
'1-d array, or Series')
arg = _ensure_object(arg)
require_iso8601 = False
if infer_datetime_format and format is None:
format = _guess_datetime_format_for_array(arg, dayfirst=dayfirst)
if format is not None:
# There is a special fast-path for iso8601 formatted
# datetime strings, so in those cases don't use the inferred
# format because this path makes process slower in this
# special case
format_is_iso8601 = _format_is_iso(format)
if format_is_iso8601:
require_iso8601 = not infer_datetime_format
format = None
try:
result = None
if format is not None:
# shortcut formatting here
if format == '%Y%m%d':
try:
result = _attempt_YYYYMMDD(arg, errors=errors)
except:
raise ValueError("cannot convert the input to "
"'%Y%m%d' date format")
# fallback
if result is None:
try:
result, timezones = array_strptime(arg,
format,
exact=exact,
errors=errors)
if '%Z' in format or '%z' in format:
return _return_parsed_timezone_results(
result, timezones, box, tz)
except tslib.OutOfBoundsDatetime:
if errors == 'raise':
raise
result = arg
except ValueError:
# if format was inferred, try falling back
# to array_to_datetime - terminate here
# for specified formats
if not infer_datetime_format:
if errors == 'raise':
raise
result = arg
if result is None and (format is None or infer_datetime_format):
result = tslib.array_to_datetime(arg,
errors=errors,
utc=tz == 'utc',
dayfirst=dayfirst,
yearfirst=yearfirst,
require_iso8601=require_iso8601)
if is_datetime64_dtype(result) and box:
result = DatetimeIndex(result, tz=tz, name=name)
return result
except ValueError as e:
try:
values, tz = conversion.datetime_to_datetime64(arg)
return DatetimeIndex._simple_new(values, name=name, tz=tz)
except (ValueError, TypeError):
raise e
def _convert_listlike_datetimes(arg, box, format, name=None, tz=None,
unit=None, errors=None,
infer_datetime_format=None, dayfirst=None,
yearfirst=None, exact=None):
"""
Helper function for to_datetime. Performs the conversions of 1D listlike
of dates
Parameters
----------
arg : list, tuple, ndarray, Series, Index
date to be parced
box : boolean
True boxes result as an Index-like, False returns an ndarray
name : object
None or string for the Index name
tz : object
None or 'utc'
unit : string
None or string of the frequency of the passed data
errors : string
error handing behaviors from to_datetime, 'raise', 'coerce', 'ignore'
infer_datetime_format : boolean
inferring format behavior from to_datetime
dayfirst : boolean
dayfirst parsing behavior from to_datetime
yearfirst : boolean
yearfirst parsing behavior from to_datetime
exact : boolean
exact format matching behavior from to_datetime
Returns
-------
ndarray of parsed dates
Returns:
- Index-like if box=True
- ndarray of Timestamps if box=False
"""
from pandas import DatetimeIndex
if isinstance(arg, (list, tuple)):
arg = np.array(arg, dtype='O')
# these are shortcutable
if is_datetime64tz_dtype(arg):
if not isinstance(arg, DatetimeIndex):
return DatetimeIndex(arg, tz=tz, name=name)
if tz == 'utc':
arg = arg.tz_convert(None).tz_localize(tz)
return arg
elif is_datetime64_ns_dtype(arg):
if box and not isinstance(arg, DatetimeIndex):
try:
return DatetimeIndex(arg, tz=tz, name=name)
except ValueError:
pass
return arg
elif unit is not None:
if format is not None:
raise ValueError("cannot specify both format and unit")
arg = getattr(arg, 'values', arg)
result = tslib.array_with_unit_to_datetime(arg, unit,
errors=errors)
if box:
if errors == 'ignore':
from pandas import Index
return Index(result)
return DatetimeIndex(result, tz=tz, name=name)
return result
elif getattr(arg, 'ndim', 1) > 1:
raise TypeError('arg must be a string, datetime, list, tuple, '
'1-d array, or Series')
arg = _ensure_object(arg)
require_iso8601 = False
if infer_datetime_format and format is None:
format = _guess_datetime_format_for_array(arg, dayfirst=dayfirst)
if format is not None:
# There is a special fast-path for iso8601 formatted
# datetime strings, so in those cases don't use the inferred
# format because this path makes process slower in this
# special case
format_is_iso8601 = _format_is_iso(format)
if format_is_iso8601:
require_iso8601 = not infer_datetime_format
format = None
try:
result = None
if format is not None:
# shortcut formatting here
if format == '%Y%m%d':
try:
result = _attempt_YYYYMMDD(arg, errors=errors)
except:
raise ValueError("cannot convert the input to "
"'%Y%m%d' date format")
# fallback
if result is None:
try:
result, timezones = array_strptime(
arg, format, exact=exact, errors=errors)
if '%Z' in format or '%z' in format:
return _return_parsed_timezone_results(
result, timezones, box, tz)
except tslibs.OutOfBoundsDatetime:
if errors == 'raise':
raise
result = arg
except ValueError:
# if format was inferred, try falling back
# to array_to_datetime - terminate here
# for specified formats
if not infer_datetime_format:
if errors == 'raise':
raise
result = arg
if result is None and (format is None or infer_datetime_format):
result = tslib.array_to_datetime(
arg,
errors=errors,
utc=tz == 'utc',
dayfirst=dayfirst,
yearfirst=yearfirst,
require_iso8601=require_iso8601
)
if is_datetime64_dtype(result) and box:
result = DatetimeIndex(result, tz=tz, name=name)
return result
except ValueError as e:
try:
values, tz = conversion.datetime_to_datetime64(arg)
return DatetimeIndex._simple_new(values, name=name, tz=tz)
except (ValueError, TypeError):
raise e
def to_numeric(arg, errors='raise', downcast=None):
"""
Convert argument to a numeric type.
The default return dtype is `float64` or `int64`
depending on the data supplied. Use the `downcast` parameter
to obtain other dtypes.
Parameters
----------
arg : list, tuple, 1-d array, or Series
errors : {'ignore', 'raise', 'coerce'}, default 'raise'
- If 'raise', then invalid parsing will raise an exception
- If 'coerce', then invalid parsing will be set as NaN
- If 'ignore', then invalid parsing will return the input
downcast : {'integer', 'signed', 'unsigned', 'float'} , default None
If not None, and if the data has been successfully cast to a
numerical dtype (or if the data was numeric to begin with),
downcast that resulting data to the smallest numerical dtype
possible according to the following rules:
- 'integer' or 'signed': smallest signed int dtype (min.: np.int8)
- 'unsigned': smallest unsigned int dtype (min.: np.uint8)
- 'float': smallest float dtype (min.: np.float32)
As this behaviour is separate from the core conversion to
numeric values, any errors raised during the downcasting
will be surfaced regardless of the value of the 'errors' input.
In addition, downcasting will only occur if the size
of the resulting data's dtype is strictly larger than
the dtype it is to be cast to, so if none of the dtypes
checked satisfy that specification, no downcasting will be
performed on the data.
.. versionadded:: 0.19.0
Returns
-------
ret : numeric if parsing succeeded.
Return type depends on input. Series if Series, otherwise ndarray
Examples
--------
Take separate series and convert to numeric, coercing when told to
>>> import pandas as pd
>>> s = pd.Series(['1.0', '2', -3])
>>> pd.to_numeric(s)
0 1.0
1 2.0
2 -3.0
dtype: float64
>>> pd.to_numeric(s, downcast='float')
0 1.0
1 2.0
2 -3.0
dtype: float32
>>> pd.to_numeric(s, downcast='signed')
0 1
1 2
2 -3
dtype: int8
>>> s = pd.Series(['apple', '1.0', '2', -3])
>>> pd.to_numeric(s, errors='ignore')
0 apple
1 1.0
2 2
3 -3
dtype: object
>>> pd.to_numeric(s, errors='coerce')
0 NaN
1 1.0
2 2.0
3 -3.0
dtype: float64
See also
--------
pandas.DataFrame.astype : Cast argument to a specified dtype.
pandas.to_datetime : Convert argument to datetime.
pandas.to_timedelta : Convert argument to timedelta.
numpy.ndarray.astype : Cast a numpy array to a specified type.
"""
if downcast not in (None, 'integer', 'signed', 'unsigned', 'float'):
raise ValueError('invalid downcasting method provided')
is_series = False
is_index = False
is_scalars = False
if isinstance(arg, ABCSeries):
is_series = True
values = arg.values
elif isinstance(arg, ABCIndexClass):
is_index = True
values = arg.asi8
if values is None:
values = arg.values
elif isinstance(arg, (list, tuple)):
values = np.array(arg, dtype='O')
elif is_scalar(arg):
if is_decimal(arg):
return float(arg)
if is_number(arg):
return arg
is_scalars = True
values = np.array([arg], dtype='O')
elif getattr(arg, 'ndim', 1) > 1:
raise TypeError('arg must be a list, tuple, 1-d array, or Series')
else:
values = arg
try:
if is_numeric_dtype(values):
pass
elif is_datetime_or_timedelta_dtype(values):
values = values.astype(np.int64)
else:
values = _ensure_object(values)
coerce_numeric = False if errors in ('ignore', 'raise') else True
values = lib.maybe_convert_numeric(values, set(),
coerce_numeric=coerce_numeric)
except Exception:
if errors == 'raise':
raise
# attempt downcast only if the data has been successfully converted
# to a numerical dtype and if a downcast method has been specified
if downcast is not None and is_numeric_dtype(values):
typecodes = None
if downcast in ('integer', 'signed'):
typecodes = np.typecodes['Integer']
elif downcast == 'unsigned' and np.min(values) >= 0:
typecodes = np.typecodes['UnsignedInteger']
elif downcast == 'float':
typecodes = np.typecodes['Float']
# pandas support goes only to np.float32,
# as float dtypes smaller than that are
# extremely rare and not well supported
float_32_char = np.dtype(np.float32).char
float_32_ind = typecodes.index(float_32_char)
typecodes = typecodes[float_32_ind:]
if typecodes is not None:
# from smallest to largest
for dtype in typecodes:
if np.dtype(dtype).itemsize <= values.dtype.itemsize:
values = maybe_downcast_to_dtype(values, dtype)
# successful conversion
if values.dtype == dtype:
break
if is_series:
return pd.Series(values, index=arg.index, name=arg.name)
elif is_index:
# because we want to coerce to numeric if possible,
# do not use _shallow_copy_with_infer
return pd.Index(values, name=arg.name)
elif is_scalars:
return values[0]
else:
return values
def _cython_operation(self, kind, values, how, axis, min_count=-1,
**kwargs):
assert kind in ['transform', 'aggregate']
# can we do this operation with our cython functions
# if not raise NotImplementedError
# we raise NotImplemented if this is an invalid operation
# entirely, e.g. adding datetimes
# categoricals are only 1d, so we
# are not setup for dim transforming
if is_categorical_dtype(values):
raise NotImplementedError(
"categoricals are not support in cython ops ATM")
elif is_datetime64_any_dtype(values):
if how in ['add', 'prod', 'cumsum', 'cumprod']:
raise NotImplementedError(
"datetime64 type does not support {} "
"operations".format(how))
elif is_timedelta64_dtype(values):
if how in ['prod', 'cumprod']:
raise NotImplementedError(
"timedelta64 type does not support {} "
"operations".format(how))
arity = self._cython_arity.get(how, 1)
vdim = values.ndim
swapped = False
if vdim == 1:
values = values[:, None]
out_shape = (self.ngroups, arity)
else:
if axis > 0:
swapped = True
values = values.swapaxes(0, axis)
if arity > 1:
raise NotImplementedError("arity of more than 1 is not "
"supported for the 'how' argument")
out_shape = (self.ngroups,) + values.shape[1:]
is_datetimelike = needs_i8_conversion(values.dtype)
is_numeric = is_numeric_dtype(values.dtype)
if is_datetimelike:
values = values.view('int64')
is_numeric = True
elif is_bool_dtype(values.dtype):
values = _ensure_float64(values)
elif is_integer_dtype(values):
# we use iNaT for the missing value on ints
# so pre-convert to guard this condition
if (values == iNaT).any():
values = _ensure_float64(values)
else:
values = values.astype('int64', copy=False)
elif is_numeric and not is_complex_dtype(values):
values = _ensure_float64(values)
else:
values = values.astype(object)
try:
func = self._get_cython_function(
kind, how, values, is_numeric)
except NotImplementedError:
if is_numeric:
values = _ensure_float64(values)
func = self._get_cython_function(
kind, how, values, is_numeric)
else:
raise
if how == 'rank':
out_dtype = 'float'
else:
if is_numeric:
out_dtype = '%s%d' % (values.dtype.kind, values.dtype.itemsize)
else:
out_dtype = 'object'
labels, _, _ = self.group_info
if kind == 'aggregate':
result = _maybe_fill(np.empty(out_shape, dtype=out_dtype),
fill_value=np.nan)
counts = np.zeros(self.ngroups, dtype=np.int64)
result = self._aggregate(
result, counts, values, labels, func, is_numeric,
is_datetimelike, min_count)
elif kind == 'transform':
result = _maybe_fill(np.empty_like(values, dtype=out_dtype),
fill_value=np.nan)
# TODO: min_count
result = self._transform(
result, values, labels, func, is_numeric, is_datetimelike,
**kwargs)
if is_integer_dtype(result) and not is_datetimelike:
mask = result == iNaT
if mask.any():
result = result.astype('float64')
result[mask] = np.nan
if kind == 'aggregate' and \
self._filter_empty_groups and not counts.all():
if result.ndim == 2:
try:
result = lib.row_bool_subset(
result, (counts > 0).view(np.uint8))
except ValueError:
result = lib.row_bool_subset_object(
_ensure_object(result),
(counts > 0).view(np.uint8))
else:
result = result[counts > 0]
if vdim == 1 and arity == 1:
result = result[:, 0]
if how in self._name_functions:
# TODO
names = self._name_functions[how]()
else:
names = None
if swapped:
result = result.swapaxes(0, axis)
return result, names
