#!/usr/bin/env python
# encoding: utf-8
#
# Copyright © 2019, SAS Institute Inc., Cary, NC, USA. All Rights Reserved.
# SPDX-License-Identifier: Apache-2.0
import logging
import re
from collections import OrderedDict
from inspect import getfullargspec, getsourcelines
from ..decorators import versionchanged
from .ds2 import DS2Variable
logger = logging.getLogger(__name__)
[docs]
@versionchanged("`names` parameter added.", version="1.5")
def ds2_variables(input, output_vars=False, names=None):
"""Generate a collection of `DS2Variable` instances corresponding to the input
Parameters
----------
input : Callable or OrderedDict[str, tuple] or OrderedDict[str, type] or pandas.DataFrame
a function or mapping parameter names to (type, is_output)
output_vars : bool
Whether or not to treat all variables from `input` as output variables
names : list of str
List of variable names to used. If a single string is specified it will
be used as a prefix and variable names in the format "prefixNN" will be
generated.
Returns
-------
list of DS2Variable
Examples
--------
>>> ds2_variables(OrderedDict(a=int, c=float))
[DS2Variable(name='a', type='integer', out=False), DS2Variable(name='c', type='double', out=False)]
>>> ds2_variables({'x': (float, True)})
[DS2Variable(name='x', type='double', out=True)]
"""
if isinstance(input, dict):
types = input
elif hasattr(input, "columns") and hasattr(input, "dtypes"):
# Pandas DataFrame
types = OrderedDict()
for col in input.columns:
if input[col].dtype.name == "object":
types[col] = ("char", False)
elif input[col].dtype.name == "category":
types[col] = ("char", False)
else:
types[col] = (input[col].dtype.name, False)
elif hasattr(input, "dtype"):
# Numpy array? No column names, but we can at least create dummy vars of the correct type
types = OrderedDict(
[
("var{}".format(i), (input.dtype.name.replace("object", "char"), False))
for i in range(1, input.size + 1)
]
)
elif callable(input):
types = parse_type_hints(input)
else:
raise RuntimeError(
"Unable to determine input/ouput types using "
"instance of type '%s'." % type(input)
)
if isinstance(names, str):
names = [names + str(i) for i in range(1, len(types) + 1)]
elif names is None:
names = list(types.keys())
results = []
for v in types.values():
name = names.pop(0)
if isinstance(v, str):
results.append(DS2Variable(name=name, type=v, out=output_vars))
elif isinstance(v, type):
results.append(DS2Variable(name=name, type=v.__name__, out=output_vars))
elif isinstance(v, tuple):
type_ = v[0].__name__ if isinstance(v[0], type) else str(v[0])
out = v[1] or output_vars
results.append(DS2Variable(name=name, type=type_, out=out))
else:
raise RuntimeError("Unable to determine input/ouput types.")
return results
[docs]
def parse_type_hints(func, skip_var="self"):
"""Attempt to discern types for the input and output variable(s).
DS2 is a strongly-typed language but Python is not. Need to determine the types for input/output variables so they
can be correctly mapped to DS2 types.
Parameters
----------
func : Callable
the object to inspect for parameters
skip_var : str
name of the variable assumed to be the instance reference, if any. Will be ignored during parameter parsing.
Returns
-------
params : OrderedDict
dictionary of str : (str, bool) mapping param_name : (param_type, is_return_val)
Raises
------
ValueError
If the type of one or more variables could not be determined.
"""
params = OrderedDict(
[(k, None) for k in getfullargspec(func).args if k != skip_var]
)
logger.debug("Params: {}".format(params))
if getattr(func, "__annotations__", None):
params.update(parse_type_hints_from_annotations(func, skip_var=skip_var))
else:
params.update(parse_type_hints_from_source(func, skip_var=skip_var))
if any(v is None for v in params.values()):
raise ValueError("Unable to determine parameter types.")
return params
[docs]
def parse_type_hints_from_source(func, skip_var="self"):
"""Parse type hints stored in comments according to PEP 484."""
regex = re.compile(r"^\s+\# types?: ", re.IGNORECASE)
def parse_types(line):
if line:
line = regex.sub("", line) # Strip out the ' # type:' portion if it exists
return line.strip().strip("(").strip(")").split(",")
return []
params = OrderedDict()
for line in getsourcelines(func)[0]:
if regex.match(line):
if "->" in line:
inputs, outputs = line.split("->")
else:
inputs = line
outputs = None
types = parse_types(inputs)
args = getfullargspec(func).args # skipcq PYL-W1505
try:
args.remove(skip_var)
except ValueError:
pass
for a, t in zip(args, types):
params[a] = (t.strip(), False)
types = parse_types(outputs)
for i, t in enumerate(types):
params["out%d" % (i + 1)] = (t.strip(), True)
return params
[docs]
def parse_type_hints_from_annotations(func, skip_var="self"):
"""Parse type hints from the function signature."""
annotations = func.__annotations__
params = OrderedDict()
logger.debug("Annotations: {}".format(annotations))
for p, t in annotations.items():
if p == skip_var:
continue
elif p == "return":
if t is not None:
params[p] = (t.__name__, True)
else:
params[p] = (t.__name__, False)
return params
