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stata.py
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stata.py
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"""
Module contains tools for processing Stata files into DataFrames
The StataReader below was originally written by Joe Presbrey as part of PyDTA.
It has been extended and improved by Skipper Seabold from the Statsmodels
project who also developed the StataWriter and was finally added to pandas in
a once again improved version.
You can find more information on http://presbrey.mit.edu/PyDTA and
http://www.statsmodels.org/devel/
"""
import numpy as np
import sys
import struct
from dateutil.relativedelta import relativedelta
from pandas.core.dtypes.common import (
is_categorical_dtype, is_datetime64_dtype,
_ensure_object)
from pandas.core.base import StringMixin
from pandas.core.categorical import Categorical
from pandas.core.frame import DataFrame
from pandas.core.series import Series
import datetime
from pandas import compat, to_timedelta, to_datetime, isnull, DatetimeIndex
from pandas.compat import lrange, lmap, lzip, text_type, string_types, range, \
zip, BytesIO
from pandas.util._decorators import Appender
import pandas as pd
from pandas.io.common import get_filepath_or_buffer, BaseIterator
from pandas._libs.lib import max_len_string_array, infer_dtype
from pandas._libs.tslib import NaT, Timestamp
VALID_ENCODINGS = ('ascii', 'us-ascii', 'latin-1', 'latin_1', 'iso-8859-1',
'iso8859-1', '8859', 'cp819', 'latin', 'latin1', 'L1')
_version_error = ("Version of given Stata file is not 104, 105, 108, "
"111 (Stata 7SE), 113 (Stata 8/9), 114 (Stata 10/11), "
"115 (Stata 12), 117 (Stata 13), or 118 (Stata 14)")
_statafile_processing_params1 = """\
convert_dates : boolean, defaults to True
Convert date variables to DataFrame time values
convert_categoricals : boolean, defaults to True
Read value labels and convert columns to Categorical/Factor variables"""
_encoding_params = """\
encoding : string, None or encoding
Encoding used to parse the files. None defaults to latin-1."""
_statafile_processing_params2 = """\
index : identifier of index column
identifier of column that should be used as index of the DataFrame
convert_missing : boolean, defaults to False
Flag indicating whether to convert missing values to their Stata
representations. If False, missing values are replaced with nans.
If True, columns containing missing values are returned with
object data types and missing values are represented by
StataMissingValue objects.
preserve_dtypes : boolean, defaults to True
Preserve Stata datatypes. If False, numeric data are upcast to pandas
default types for foreign data (float64 or int64)
columns : list or None
Columns to retain. Columns will be returned in the given order. None
returns all columns
order_categoricals : boolean, defaults to True
Flag indicating whether converted categorical data are ordered."""
_chunksize_params = """\
chunksize : int, default None
Return StataReader object for iterations, returns chunks with
given number of lines"""
_iterator_params = """\
iterator : boolean, default False
Return StataReader object"""
_read_stata_doc = """Read Stata file into DataFrame
Parameters
----------
filepath_or_buffer : string or file-like object
Path to .dta file or object implementing a binary read() functions
%s
%s
%s
%s
%s
Returns
-------
DataFrame or StataReader
Examples
--------
Read a Stata dta file:
>>> df = pandas.read_stata('filename.dta')
Read a Stata dta file in 10,000 line chunks:
>>> itr = pandas.read_stata('filename.dta', chunksize=10000)
>>> for chunk in itr:
>>> do_something(chunk)
""" % (_statafile_processing_params1, _encoding_params,
_statafile_processing_params2, _chunksize_params,
_iterator_params)
_data_method_doc = """Reads observations from Stata file, converting them into a dataframe
This is a legacy method. Use `read` in new code.
Parameters
----------
%s
%s
Returns
-------
DataFrame
""" % (_statafile_processing_params1, _statafile_processing_params2)
_read_method_doc = """\
Reads observations from Stata file, converting them into a dataframe
Parameters
----------
nrows : int
Number of lines to read from data file, if None read whole file.
%s
%s
Returns
-------
DataFrame
""" % (_statafile_processing_params1, _statafile_processing_params2)
_stata_reader_doc = """\
Class for reading Stata dta files.
Parameters
----------
path_or_buf : string or file-like object
Path to .dta file or object implementing a binary read() functions
%s
%s
%s
%s
""" % (_statafile_processing_params1, _statafile_processing_params2,
_encoding_params, _chunksize_params)
@Appender(_read_stata_doc)
def read_stata(filepath_or_buffer, convert_dates=True,
convert_categoricals=True, encoding=None, index=None,
convert_missing=False, preserve_dtypes=True, columns=None,
order_categoricals=True, chunksize=None, iterator=False):
reader = StataReader(filepath_or_buffer,
convert_dates=convert_dates,
convert_categoricals=convert_categoricals,
index=index, convert_missing=convert_missing,
preserve_dtypes=preserve_dtypes,
columns=columns,
order_categoricals=order_categoricals,
chunksize=chunksize, encoding=encoding)
if iterator or chunksize:
data = reader
else:
try:
data = reader.read()
finally:
reader.close()
return data
_date_formats = ["%tc", "%tC", "%td", "%d", "%tw", "%tm", "%tq", "%th", "%ty"]
stata_epoch = datetime.datetime(1960, 1, 1)
def _stata_elapsed_date_to_datetime_vec(dates, fmt):
"""
Convert from SIF to datetime. http://www.stata.com/help.cgi?datetime
Parameters
----------
dates : Series
The Stata Internal Format date to convert to datetime according to fmt
fmt : str
The format to convert to. Can be, tc, td, tw, tm, tq, th, ty
Returns
Returns
-------
converted : Series
The converted dates
Examples
--------
>>> import pandas as pd
>>> dates = pd.Series([52])
>>> _stata_elapsed_date_to_datetime_vec(dates , "%tw")
0 1961-01-01
dtype: datetime64[ns]
Notes
-----
datetime/c - tc
milliseconds since 01jan1960 00:00:00.000, assuming 86,400 s/day
datetime/C - tC - NOT IMPLEMENTED
milliseconds since 01jan1960 00:00:00.000, adjusted for leap seconds
date - td
days since 01jan1960 (01jan1960 = 0)
weekly date - tw
weeks since 1960w1
This assumes 52 weeks in a year, then adds 7 * remainder of the weeks.
The datetime value is the start of the week in terms of days in the
year, not ISO calendar weeks.
monthly date - tm
months since 1960m1
quarterly date - tq
quarters since 1960q1
half-yearly date - th
half-years since 1960h1 yearly
date - ty
years since 0000
If you don't have pandas with datetime support, then you can't do
milliseconds accurately.
"""
MIN_YEAR, MAX_YEAR = Timestamp.min.year, Timestamp.max.year
MAX_DAY_DELTA = (Timestamp.max - datetime.datetime(1960, 1, 1)).days
MIN_DAY_DELTA = (Timestamp.min - datetime.datetime(1960, 1, 1)).days
MIN_MS_DELTA = MIN_DAY_DELTA * 24 * 3600 * 1000
MAX_MS_DELTA = MAX_DAY_DELTA * 24 * 3600 * 1000
def convert_year_month_safe(year, month):
"""
Convert year and month to datetimes, using pandas vectorized versions
when the date range falls within the range supported by pandas. Other
wise it falls back to a slower but more robust method using datetime.
"""
if year.max() < MAX_YEAR and year.min() > MIN_YEAR:
return to_datetime(100 * year + month, format='%Y%m')
else:
index = getattr(year, 'index', None)
return Series(
[datetime.datetime(y, m, 1) for y, m in zip(year, month)],
index=index)
def convert_year_days_safe(year, days):
"""
Converts year (e.g. 1999) and days since the start of the year to a
datetime or datetime64 Series
"""
if year.max() < (MAX_YEAR - 1) and year.min() > MIN_YEAR:
return (to_datetime(year, format='%Y') +
to_timedelta(days, unit='d'))
else:
index = getattr(year, 'index', None)
value = [datetime.datetime(y, 1, 1) + relativedelta(days=int(d))
for y, d in zip(year, days)]
return Series(value, index=index)
def convert_delta_safe(base, deltas, unit):
"""
Convert base dates and deltas to datetimes, using pandas vectorized
versions if the deltas satisfy restrictions required to be expressed
as dates in pandas.
"""
index = getattr(deltas, 'index', None)
if unit == 'd':
if deltas.max() > MAX_DAY_DELTA or deltas.min() < MIN_DAY_DELTA:
values = [base + relativedelta(days=int(d)) for d in deltas]
return Series(values, index=index)
elif unit == 'ms':
if deltas.max() > MAX_MS_DELTA or deltas.min() < MIN_MS_DELTA:
values = [base + relativedelta(microseconds=(int(d) * 1000))
for d in deltas]
return Series(values, index=index)
else:
raise ValueError('format not understood')
base = to_datetime(base)
deltas = to_timedelta(deltas, unit=unit)
return base + deltas
# TODO: If/when pandas supports more than datetime64[ns], this should be
# improved to use correct range, e.g. datetime[Y] for yearly
bad_locs = np.isnan(dates)
has_bad_values = False
if bad_locs.any():
has_bad_values = True
data_col = Series(dates)
data_col[bad_locs] = 1.0 # Replace with NaT
dates = dates.astype(np.int64)
if fmt in ["%tc", "tc"]: # Delta ms relative to base
base = stata_epoch
ms = dates
conv_dates = convert_delta_safe(base, ms, 'ms')
elif fmt in ["%tC", "tC"]:
from warnings import warn
warn("Encountered %tC format. Leaving in Stata Internal Format.")
conv_dates = Series(dates, dtype=np.object)
if has_bad_values:
conv_dates[bad_locs] = pd.NaT
return conv_dates
elif fmt in ["%td", "td", "%d", "d"]: # Delta days relative to base
base = stata_epoch
days = dates
conv_dates = convert_delta_safe(base, days, 'd')
elif fmt in ["%tw", "tw"]: # does not count leap days - 7 days is a week
year = stata_epoch.year + dates // 52
days = (dates % 52) * 7
conv_dates = convert_year_days_safe(year, days)
elif fmt in ["%tm", "tm"]: # Delta months relative to base
year = stata_epoch.year + dates // 12
month = (dates % 12) + 1
conv_dates = convert_year_month_safe(year, month)
elif fmt in ["%tq", "tq"]: # Delta quarters relative to base
year = stata_epoch.year + dates // 4
month = (dates % 4) * 3 + 1
conv_dates = convert_year_month_safe(year, month)
elif fmt in ["%th", "th"]: # Delta half-years relative to base
year = stata_epoch.year + dates // 2
month = (dates % 2) * 6 + 1
conv_dates = convert_year_month_safe(year, month)
elif fmt in ["%ty", "ty"]: # Years -- not delta
year = dates
month = np.ones_like(dates)
conv_dates = convert_year_month_safe(year, month)
else:
raise ValueError("Date fmt %s not understood" % fmt)
if has_bad_values: # Restore NaT for bad values
conv_dates[bad_locs] = NaT
return conv_dates
def _datetime_to_stata_elapsed_vec(dates, fmt):
"""
Convert from datetime to SIF. http://www.stata.com/help.cgi?datetime
Parameters
----------
dates : Series
Series or array containing datetime.datetime or datetime64[ns] to
convert to the Stata Internal Format given by fmt
fmt : str
The format to convert to. Can be, tc, td, tw, tm, tq, th, ty
"""
index = dates.index
NS_PER_DAY = 24 * 3600 * 1000 * 1000 * 1000
US_PER_DAY = NS_PER_DAY / 1000
def parse_dates_safe(dates, delta=False, year=False, days=False):
d = {}
if is_datetime64_dtype(dates.values):
if delta:
delta = dates - stata_epoch
d['delta'] = delta.values.astype(
np.int64) // 1000 # microseconds
if days or year:
dates = DatetimeIndex(dates)
d['year'], d['month'] = dates.year, dates.month
if days:
days = (dates.astype(np.int64) -
to_datetime(d['year'], format='%Y').astype(np.int64))
d['days'] = days // NS_PER_DAY
elif infer_dtype(dates) == 'datetime':
if delta:
delta = dates.values - stata_epoch
f = lambda x: \
US_PER_DAY * x.days + 1000000 * x.seconds + x.microseconds
v = np.vectorize(f)
d['delta'] = v(delta)
if year:
year_month = dates.apply(lambda x: 100 * x.year + x.month)
d['year'] = year_month.values // 100
d['month'] = (year_month.values - d['year'] * 100)
if days:
f = lambda x: (x - datetime.datetime(x.year, 1, 1)).days
v = np.vectorize(f)
d['days'] = v(dates)
else:
raise ValueError('Columns containing dates must contain either '
'datetime64, datetime.datetime or null values.')
return DataFrame(d, index=index)
bad_loc = isnull(dates)
index = dates.index
if bad_loc.any():
dates = Series(dates)
if is_datetime64_dtype(dates):
dates[bad_loc] = to_datetime(stata_epoch)
else:
dates[bad_loc] = stata_epoch
if fmt in ["%tc", "tc"]:
d = parse_dates_safe(dates, delta=True)
conv_dates = d.delta / 1000
elif fmt in ["%tC", "tC"]:
from warnings import warn
warn("Stata Internal Format tC not supported.")
conv_dates = dates
elif fmt in ["%td", "td"]:
d = parse_dates_safe(dates, delta=True)
conv_dates = d.delta // US_PER_DAY
elif fmt in ["%tw", "tw"]:
d = parse_dates_safe(dates, year=True, days=True)
conv_dates = (52 * (d.year - stata_epoch.year) + d.days // 7)
elif fmt in ["%tm", "tm"]:
d = parse_dates_safe(dates, year=True)
conv_dates = (12 * (d.year - stata_epoch.year) + d.month - 1)
elif fmt in ["%tq", "tq"]:
d = parse_dates_safe(dates, year=True)
conv_dates = 4 * (d.year - stata_epoch.year) + (d.month - 1) // 3
elif fmt in ["%th", "th"]:
d = parse_dates_safe(dates, year=True)
conv_dates = 2 * (d.year - stata_epoch.year) + \
(d.month > 6).astype(np.int)
elif fmt in ["%ty", "ty"]:
d = parse_dates_safe(dates, year=True)
conv_dates = d.year
else:
raise ValueError("Format %s is not a known Stata date format" % fmt)
conv_dates = Series(conv_dates, dtype=np.float64)
missing_value = struct.unpack('<d', b'\x00\x00\x00\x00\x00\x00\xe0\x7f')[0]
conv_dates[bad_loc] = missing_value
return Series(conv_dates, index=index)
excessive_string_length_error = """
Fixed width strings in Stata .dta files are limited to 244 (or fewer)
characters. Column '%s' does not satisfy this restriction.
"""
class PossiblePrecisionLoss(Warning):
pass
precision_loss_doc = """
Column converted from %s to %s, and some data are outside of the lossless
conversion range. This may result in a loss of precision in the saved data.
"""
class ValueLabelTypeMismatch(Warning):
pass
value_label_mismatch_doc = """
Stata value labels (pandas categories) must be strings. Column {0} contains
non-string labels which will be converted to strings. Please check that the
Stata data file created has not lost information due to duplicate labels.
"""
class InvalidColumnName(Warning):
pass
invalid_name_doc = """
Not all pandas column names were valid Stata variable names.
The following replacements have been made:
{0}
If this is not what you expect, please make sure you have Stata-compliant
column names in your DataFrame (strings only, max 32 characters, only
alphanumerics and underscores, no Stata reserved words)
"""
def _cast_to_stata_types(data):
"""Checks the dtypes of the columns of a pandas DataFrame for
compatibility with the data types and ranges supported by Stata, and
converts if necessary.
Parameters
----------
data : DataFrame
The DataFrame to check and convert
Notes
-----
Numeric columns in Stata must be one of int8, int16, int32, float32 or
float64, with some additional value restrictions. int8 and int16 columns
are checked for violations of the value restrictions and upcast if needed.
int64 data is not usable in Stata, and so it is downcast to int32 whenever
the value are in the int32 range, and sidecast to float64 when larger than
this range. If the int64 values are outside of the range of those
perfectly representable as float64 values, a warning is raised.
bool columns are cast to int8. uint colums are converted to int of the
same size if there is no loss in precision, other wise are upcast to a
larger type. uint64 is currently not supported since it is concerted to
object in a DataFrame.
"""
ws = ''
# original, if small, if large
conversion_data = ((np.bool, np.int8, np.int8),
(np.uint8, np.int8, np.int16),
(np.uint16, np.int16, np.int32),
(np.uint32, np.int32, np.int64))
float32_max = struct.unpack('<f', b'\xff\xff\xff\x7e')[0]
float64_max = struct.unpack('<d', b'\xff\xff\xff\xff\xff\xff\xdf\x7f')[0]
for col in data:
dtype = data[col].dtype
# Cast from unsupported types to supported types
for c_data in conversion_data:
if dtype == c_data[0]:
if data[col].max() <= np.iinfo(c_data[1]).max:
dtype = c_data[1]
else:
dtype = c_data[2]
if c_data[2] == np.float64: # Warn if necessary
if data[col].max() >= 2 ** 53:
ws = precision_loss_doc % ('uint64', 'float64')
data[col] = data[col].astype(dtype)
# Check values and upcast if necessary
if dtype == np.int8:
if data[col].max() > 100 or data[col].min() < -127:
data[col] = data[col].astype(np.int16)
elif dtype == np.int16:
if data[col].max() > 32740 or data[col].min() < -32767:
data[col] = data[col].astype(np.int32)
elif dtype == np.int64:
if (data[col].max() <= 2147483620 and
data[col].min() >= -2147483647):
data[col] = data[col].astype(np.int32)
else:
data[col] = data[col].astype(np.float64)
if data[col].max() >= 2 ** 53 or data[col].min() <= -2 ** 53:
ws = precision_loss_doc % ('int64', 'float64')
elif dtype in (np.float32, np.float64):
value = data[col].max()
if np.isinf(value):
msg = 'Column {0} has a maximum value of infinity which is ' \
'outside the range supported by Stata.'
raise ValueError(msg.format(col))
if dtype == np.float32 and value > float32_max:
data[col] = data[col].astype(np.float64)
elif dtype == np.float64:
if value > float64_max:
msg = 'Column {0} has a maximum value ({1}) outside the ' \
'range supported by Stata ({1})'
raise ValueError(msg.format(col, value, float64_max))
if ws:
import warnings
warnings.warn(ws, PossiblePrecisionLoss)
return data
class StataValueLabel(object):
"""
Parse a categorical column and prepare formatted output
Parameters
-----------
value : int8, int16, int32, float32 or float64
The Stata missing value code
Attributes
----------
string : string
String representation of the Stata missing value
value : int8, int16, int32, float32 or float64
The original encoded missing value
Methods
-------
generate_value_label
"""
def __init__(self, catarray):
self.labname = catarray.name
categories = catarray.cat.categories
self.value_labels = list(zip(np.arange(len(categories)), categories))
self.value_labels.sort(key=lambda x: x[0])
self.text_len = np.int32(0)
self.off = []
self.val = []
self.txt = []
self.n = 0
# Compute lengths and setup lists of offsets and labels
for vl in self.value_labels:
category = vl[1]
if not isinstance(category, string_types):
category = str(category)
import warnings
warnings.warn(value_label_mismatch_doc.format(catarray.name),
ValueLabelTypeMismatch)
self.off.append(self.text_len)
self.text_len += len(category) + 1 # +1 for the padding
self.val.append(vl[0])
self.txt.append(category)
self.n += 1
if self.text_len > 32000:
raise ValueError('Stata value labels for a single variable must '
'have a combined length less than 32,000 '
'characters.')
# Ensure int32
self.off = np.array(self.off, dtype=np.int32)
self.val = np.array(self.val, dtype=np.int32)
# Total length
self.len = 4 + 4 + 4 * self.n + 4 * self.n + self.text_len
def _encode(self, s):
"""
Python 3 compatability shim
"""
if compat.PY3:
return s.encode(self._encoding)
else:
return s
def generate_value_label(self, byteorder, encoding):
"""
Parameters
----------
byteorder : str
Byte order of the output
encoding : str
File encoding
Returns
-------
value_label : bytes
Bytes containing the formatted value label
"""
self._encoding = encoding
bio = BytesIO()
null_string = '\x00'
null_byte = b'\x00'
# len
bio.write(struct.pack(byteorder + 'i', self.len))
# labname
labname = self._encode(_pad_bytes(self.labname[:32], 33))
bio.write(labname)
# padding - 3 bytes
for i in range(3):
bio.write(struct.pack('c', null_byte))
# value_label_table
# n - int32
bio.write(struct.pack(byteorder + 'i', self.n))
# textlen - int32
bio.write(struct.pack(byteorder + 'i', self.text_len))
# off - int32 array (n elements)
for offset in self.off:
bio.write(struct.pack(byteorder + 'i', offset))
# val - int32 array (n elements)
for value in self.val:
bio.write(struct.pack(byteorder + 'i', value))
# txt - Text labels, null terminated
for text in self.txt:
bio.write(self._encode(text + null_string))
bio.seek(0)
return bio.read()
class StataMissingValue(StringMixin):
"""
An observation's missing value.
Parameters
-----------
value : int8, int16, int32, float32 or float64
The Stata missing value code
Attributes
----------
string : string
String representation of the Stata missing value
value : int8, int16, int32, float32 or float64
The original encoded missing value
Notes
-----
More information: <http://www.stata.com/help.cgi?missing>
Integer missing values make the code '.', '.a', ..., '.z' to the ranges
101 ... 127 (for int8), 32741 ... 32767 (for int16) and 2147483621 ...
2147483647 (for int32). Missing values for floating point data types are
more complex but the pattern is simple to discern from the following table.
np.float32 missing values (float in Stata)
0000007f .
0008007f .a
0010007f .b
...
00c0007f .x
00c8007f .y
00d0007f .z
np.float64 missing values (double in Stata)
000000000000e07f .
000000000001e07f .a
000000000002e07f .b
...
000000000018e07f .x
000000000019e07f .y
00000000001ae07f .z
"""
# Construct a dictionary of missing values
MISSING_VALUES = {}
bases = (101, 32741, 2147483621)
for b in bases:
# Conversion to long to avoid hash issues on 32 bit platforms #8968
MISSING_VALUES[compat.long(b)] = '.'
for i in range(1, 27):
MISSING_VALUES[compat.long(i + b)] = '.' + chr(96 + i)
float32_base = b'\x00\x00\x00\x7f'
increment = struct.unpack('<i', b'\x00\x08\x00\x00')[0]
for i in range(27):
value = struct.unpack('<f', float32_base)[0]
MISSING_VALUES[value] = '.'
if i > 0:
MISSING_VALUES[value] += chr(96 + i)
int_value = struct.unpack('<i', struct.pack('<f', value))[
0] + increment
float32_base = struct.pack('<i', int_value)
float64_base = b'\x00\x00\x00\x00\x00\x00\xe0\x7f'
increment = struct.unpack('q', b'\x00\x00\x00\x00\x00\x01\x00\x00')[0]
for i in range(27):
value = struct.unpack('<d', float64_base)[0]
MISSING_VALUES[value] = '.'
if i > 0:
MISSING_VALUES[value] += chr(96 + i)
int_value = struct.unpack('q', struct.pack('<d', value))[0] + increment
float64_base = struct.pack('q', int_value)
BASE_MISSING_VALUES = {'int8': 101,
'int16': 32741,
'int32': 2147483621,
'float32': struct.unpack('<f', float32_base)[0],
'float64': struct.unpack('<d', float64_base)[0]}
def __init__(self, value):
self._value = value
# Conversion to long to avoid hash issues on 32 bit platforms #8968
value = compat.long(value) if value < 2147483648 else float(value)
self._str = self.MISSING_VALUES[value]
string = property(lambda self: self._str,
doc="The Stata representation of the missing value: "
"'.', '.a'..'.z'")
value = property(lambda self: self._value,
doc='The binary representation of the missing value.')
def __unicode__(self):
return self.string
def __repr__(self):
# not perfect :-/
return "%s(%s)" % (self.__class__, self)
def __eq__(self, other):
return (isinstance(other, self.__class__) and
self.string == other.string and self.value == other.value)
@classmethod
def get_base_missing_value(cls, dtype):
if dtype == np.int8:
value = cls.BASE_MISSING_VALUES['int8']
elif dtype == np.int16:
value = cls.BASE_MISSING_VALUES['int16']
elif dtype == np.int32:
value = cls.BASE_MISSING_VALUES['int32']
elif dtype == np.float32:
value = cls.BASE_MISSING_VALUES['float32']
elif dtype == np.float64:
value = cls.BASE_MISSING_VALUES['float64']
else:
raise ValueError('Unsupported dtype')
return value
class StataParser(object):
_default_encoding = 'latin-1'
def __init__(self, encoding):
if encoding is not None:
if encoding not in VALID_ENCODINGS:
raise ValueError('Unknown encoding. Only latin-1 and ascii '
'supported.')
self._encoding = encoding
# type code.
# --------------------
# str1 1 = 0x01
# str2 2 = 0x02
# ...
# str244 244 = 0xf4
# byte 251 = 0xfb (sic)
# int 252 = 0xfc
# long 253 = 0xfd
# float 254 = 0xfe
# double 255 = 0xff
# --------------------
# NOTE: the byte type seems to be reserved for categorical variables
# with a label, but the underlying variable is -127 to 100
# we're going to drop the label and cast to int
self.DTYPE_MAP = \
dict(
lzip(range(1, 245), ['a' + str(i) for i in range(1, 245)]) +
[
(251, np.int8),
(252, np.int16),
(253, np.int32),
(254, np.float32),
(255, np.float64)
]
)
self.DTYPE_MAP_XML = \
dict(
[
(32768, np.uint8), # Keys to GSO
(65526, np.float64),
(65527, np.float32),
(65528, np.int32),
(65529, np.int16),
(65530, np.int8)
]
)
self.TYPE_MAP = lrange(251) + list('bhlfd')
self.TYPE_MAP_XML = \
dict(
[
# Not really a Q, unclear how to handle byteswap
(32768, 'Q'),
(65526, 'd'),
(65527, 'f'),
(65528, 'l'),
(65529, 'h'),
(65530, 'b')
]
)
# NOTE: technically, some of these are wrong. there are more numbers
# that can be represented. it's the 27 ABOVE and BELOW the max listed
# numeric data type in [U] 12.2.2 of the 11.2 manual
float32_min = b'\xff\xff\xff\xfe'
float32_max = b'\xff\xff\xff\x7e'
float64_min = b'\xff\xff\xff\xff\xff\xff\xef\xff'
float64_max = b'\xff\xff\xff\xff\xff\xff\xdf\x7f'
self.VALID_RANGE = {
'b': (-127, 100),
'h': (-32767, 32740),
'l': (-2147483647, 2147483620),
'f': (np.float32(struct.unpack('<f', float32_min)[0]),
np.float32(struct.unpack('<f', float32_max)[0])),
'd': (np.float64(struct.unpack('<d', float64_min)[0]),
np.float64(struct.unpack('<d', float64_max)[0]))
}
self.OLD_TYPE_MAPPING = {
98: 251, # byte
105: 252, # int
108: 253, # long
102: 254 # float
# don't know old code for double
}
# These missing values are the generic '.' in Stata, and are used
# to replace nans
self.MISSING_VALUES = {
'b': 101,
'h': 32741,
'l': 2147483621,
'f': np.float32(struct.unpack('<f', b'\x00\x00\x00\x7f')[0]),
'd': np.float64(
struct.unpack('<d', b'\x00\x00\x00\x00\x00\x00\xe0\x7f')[0])
}
self.NUMPY_TYPE_MAP = {
'b': 'i1',
'h': 'i2',
'l': 'i4',
'f': 'f4',
'd': 'f8',
'Q': 'u8'
}
# Reserved words cannot be used as variable names
self.RESERVED_WORDS = ('aggregate', 'array', 'boolean', 'break',
'byte', 'case', 'catch', 'class', 'colvector',
'complex', 'const', 'continue', 'default',
'delegate', 'delete', 'do', 'double', 'else',
'eltypedef', 'end', 'enum', 'explicit',
'export', 'external', 'float', 'for', 'friend',
'function', 'global', 'goto', 'if', 'inline',
'int', 'local', 'long', 'NULL', 'pragma',
'protected', 'quad', 'rowvector', 'short',
'typedef', 'typename', 'virtual')
class StataReader(StataParser, BaseIterator):
__doc__ = _stata_reader_doc
def __init__(self, path_or_buf, convert_dates=True,
convert_categoricals=True, index=None,
convert_missing=False, preserve_dtypes=True,
columns=None, order_categoricals=True,
encoding='latin-1', chunksize=None):
super(StataReader, self).__init__(encoding)
self.col_sizes = ()
# Arguments to the reader (can be temporarily overridden in
# calls to read).
self._convert_dates = convert_dates
self._convert_categoricals = convert_categoricals
self._index = index
self._convert_missing = convert_missing
self._preserve_dtypes = preserve_dtypes
self._columns = columns
self._order_categoricals = order_categoricals
if encoding is not None:
if encoding not in VALID_ENCODINGS:
raise ValueError('Unknown encoding. Only latin-1 and ascii '
'supported.')
self._encoding = encoding
self._chunksize = chunksize
# State variables for the file
self._has_string_data = False
self._missing_values = False
self._can_read_value_labels = False
self._column_selector_set = False
self._value_labels_read = False
self._data_read = False
self._dtype = None
self._lines_read = 0
self._native_byteorder = _set_endianness(sys.byteorder)
if isinstance(path_or_buf, str):
path_or_buf, encoding, _ = get_filepath_or_buffer(
path_or_buf, encoding=self._default_encoding
)
if isinstance(path_or_buf, (str, compat.text_type, bytes)):
self.path_or_buf = open(path_or_buf, 'rb')
else:
# Copy to BytesIO, and ensure no encoding
contents = path_or_buf.read()
try:
contents = contents.encode(self._default_encoding)
except:
pass
self.path_or_buf = BytesIO(contents)
self._read_header()
def __enter__(self):
""" enter context manager """
return self