def _get_data_from_section(self, index):
"""
Get a dataset from an index within the data file.
:param index:
The desired index within the data file.
:return:
The data object at that index.
"""
try:
header = self.metaheader[str(index)]
except KeyError as ke:
raise exceptions.DatatypeException(
"Metaheader error: entry no. {} not found!".format(index))\
from ke
self.file.seek(self.offset + header["start byte"])
num_bytes = header["end byte"] - header["start byte"]
section = self.file.read(num_bytes)
datatype = header['datatype']
if datatype == consts.Datatypes.EVENT.value:
result = EventData.from_string(section)
elif datatype == consts.Datatypes.POINT.value:
result = PointData.from_string(section)
elif datatype == consts.Datatypes.STACK.value:
result = StackData.from_string(section)
else:
raise exceptions.DatatypeException(
"Header error: datatype '{}' not recognised!".format(datatype))
return result
def from_string(string):
"""
Converts a standard representation into a :class:`PointDatum` object.
Tolerant to whitespace/trailing linebreaks.
:param string:
The string to convert.
:raises:
exceptions.DatatypeException
:return:
The resulting :class:`PointDatum` object.
"""
try:
x, y, info = string.strip().split(consts.field_separator)
return PointDatum(x=float(x), y=float(y), info=info)
except IndexError as ie:
raise exceptions.DatatypeException(
"PointDatum - not enough values in datatype string "
"('{}')".format(string)) from ie
except ValueError as ve:
raise exceptions.DatatypeException(
"PointDatum - could not convert datatype string "
"('{}')".format(string)) from ve
def from_string(string):
"""
Converts a standard representation to a :class:`EventDatum` object.
Tolerant to whitespace/trailing linebreaks.
:param string:
The string to convert.
:raises:
exceptions.DatatypeException
:return:
The resulting :class:`EventDatum` object.
"""
try:
time, type_, datum, connected = \
string.strip().split(consts.field_separator)
return EventDatum(time=int(time),
type=type_,
specific_datum=ast.literal_eval(datum),
connected=ast.literal_eval(connected))
except IndexError as ie:
raise exceptions.DatatypeException(
"EventDatum - not enough values in datatype string "
"('{}')".format(string)) from ie
except ValueError as ve:
raise exceptions.DatatypeException(
"EventDatum - could not convert datatype string "
"('{}')".format(string)) from ve
def get_interface_from_index(self, index):
"""
Get an interface name from an index in a file.
:param index:
The index within the file.
:return:
The corresponding interface name.
"""
try:
header = self.metaheader[str(index)]
except KeyError as ke:
raise exceptions.DatatypeException(
"Metaheader error: entry no. {} not found!".format(index)) \
from ke
return header['interface']
def from_string(string):
"""
Converts a standard representation into a :class:`StackDatum` object.
Tolerant to whitespace/trailing linebreaks.
:param string:
The string to convert.
:raises:
exceptions.DatatypeException
:return:
The resulting :class:`StackDatum` object.
"""
try:
separated = string.strip().split(consts.field_separator)
weight = separated[0]
stack_tuple = tuple(separated[1:])
return StackDatum(weight=int(weight), stack=stack_tuple)
except ValueError as ve:
raise exceptions.DatatypeException(
"StackDatum - could not convert datatype string "
"('{}')".format(string)) from ve