#

Note

This documents the development version of NetworkX. Documentation for the current release can be found here.

#

Source code for networkx.utils.decorators

from collections import defaultdict
from os.path import splitext
from contextlib import contextmanager
from pathlib import Path

import networkx as nx
from decorator import decorator
from networkx.utils import create_random_state, create_py_random_state

__all__ = [
    "not_implemented_for",
    "open_file",
    "nodes_or_number",
    "preserve_random_state",
    "random_state",
    "np_random_state",
    "py_random_state",
]


[docs]def not_implemented_for(*graph_types): """Decorator to mark algorithms as not implemented Parameters ---------- graph_types : container of strings Entries must be one of 'directed','undirected', 'multigraph', 'graph'. Returns ------- _require : function The decorated function. Raises ------ NetworkXNotImplemented If any of the packages cannot be imported Notes ----- Multiple types are joined logically with "and". For "or" use multiple @not_implemented_for() lines. Examples -------- Decorate functions like this:: @not_implemnted_for('directed') def sp_function(G): pass @not_implemnted_for('directed','multigraph') def sp_np_function(G): pass """ @decorator def _not_implemented_for(not_implement_for_func, *args, **kwargs): graph = args[0] terms = { "directed": graph.is_directed(), "undirected": not graph.is_directed(), "multigraph": graph.is_multigraph(), "graph": not graph.is_multigraph(), } match = True try: for t in graph_types: match = match and terms[t] except KeyError as e: raise KeyError( "use one or more of " "directed, undirected, multigraph, graph" ) from e if match: msg = f"not implemented for {' '.join(graph_types)} type" raise nx.NetworkXNotImplemented(msg) else: return not_implement_for_func(*args, **kwargs) return _not_implemented_for
def _open_gz(path, mode): import gzip return gzip.open(path, mode=mode) def _open_bz2(path, mode): import bz2 return bz2.BZ2File(path, mode=mode) # To handle new extensions, define a function accepting a `path` and `mode`. # Then add the extension to _dispatch_dict. _dispatch_dict = defaultdict(lambda: open) _dispatch_dict[".gz"] = _open_gz _dispatch_dict[".bz2"] = _open_bz2 _dispatch_dict[".gzip"] = _open_gz
[docs]def open_file(path_arg, mode="r"): """Decorator to ensure clean opening and closing of files. Parameters ---------- path_arg : int Location of the path argument in args. Even if the argument is a named positional argument (with a default value), you must specify its index as a positional argument. mode : str String for opening mode. Returns ------- _open_file : function Function which cleanly executes the io. Examples -------- Decorate functions like this:: @open_file(0,'r') def read_function(pathname): pass @open_file(1,'w') def write_function(G,pathname): pass @open_file(1,'w') def write_function(G, pathname='graph.dot') pass @open_file('path', 'w+') def another_function(arg, **kwargs): path = kwargs['path'] pass """ # Note that this decorator solves the problem when a path argument is # specified as a string, but it does not handle the situation when the # function wants to accept a default of None (and then handle it). # Here is an example: # # @open_file('path') # def some_function(arg1, arg2, path=None): # if path is None: # fobj = tempfile.NamedTemporaryFile(delete=False) # close_fobj = True # else: # # `path` could have been a string or file object or something # # similar. In any event, the decorator has given us a file object # # and it will close it for us, if it should. # fobj = path # close_fobj = False # # try: # fobj.write('blah') # finally: # if close_fobj: # fobj.close() # # Normally, we'd want to use "with" to ensure that fobj gets closed. # However, recall that the decorator will make `path` a file object for # us, and using "with" would undesirably close that file object. Instead, # you use a try block, as shown above. When we exit the function, fobj will # be closed, if it should be, by the decorator. @decorator def _open_file(func_to_be_decorated, *args, **kwargs): # Note that since we have used @decorator, *args, and **kwargs have # already been resolved to match the function signature of func. This # means default values have been propagated. For example, the function # func(x, y, a=1, b=2, **kwargs) if called as func(0,1,b=5,c=10) would # have args=(0,1,1,5) and kwargs={'c':10}. # First we parse the arguments of the decorator. The path_arg could # be an positional argument or a keyword argument. Even if it is try: # path_arg is a required positional argument # This works precisely because we are using @decorator path = args[path_arg] except TypeError: # path_arg is a keyword argument. It is "required" in the sense # that it must exist, according to the decorator specification, # It can exist in `kwargs` by a developer specified default value # or it could have been explicitly set by the user. try: path = kwargs[path_arg] except KeyError as e: # Could not find the keyword. Thus, no default was specified # in the function signature and the user did not provide it. msg = f"Missing required keyword argument: {path_arg}" raise nx.NetworkXError(msg) from e else: is_kwarg = True except IndexError as e: # A "required" argument was missing. This can only happen if # the decorator of the function was incorrectly specified. # So this probably is not a user error, but a developer error. msg = "path_arg of open_file decorator is incorrect" raise nx.NetworkXError(msg) from e else: is_kwarg = False # Now we have the path_arg. There are two types of input to consider: # 1) string representing a path that should be opened # 2) an already opened file object if isinstance(path, str): ext = splitext(path)[1] fobj = _dispatch_dict[ext](path, mode=mode) close_fobj = True elif hasattr(path, "read"): # path is already a file-like object fobj = path close_fobj = False elif isinstance(path, Path): # path is a pathlib reference to a filename fobj = _dispatch_dict[path.suffix](str(path), mode=mode) close_fobj = True else: # could be None, in which case the algorithm will deal with it fobj = path close_fobj = False # Insert file object into args or kwargs. if is_kwarg: new_args = args kwargs[path_arg] = fobj else: # args is a tuple, so we must convert to list before modifying it. new_args = list(args) new_args[path_arg] = fobj # Finally, we call the original function, making sure to close the fobj try: result = func_to_be_decorated(*new_args, **kwargs) finally: if close_fobj: fobj.close() return result return _open_file
[docs]def nodes_or_number(which_args): """Decorator to allow number of nodes or container of nodes. Parameters ---------- which_args : int or sequence of ints Location of the node arguments in args. Even if the argument is a named positional argument (with a default value), you must specify its index as a positional argument. If more than one node argument is allowed, can be a list of locations. Returns ------- _nodes_or_numbers : function Function which replaces int args with ranges. Examples -------- Decorate functions like this:: @nodes_or_number(0) def empty_graph(nodes): pass @nodes_or_number([0,1]) def grid_2d_graph(m1, m2, periodic=False): pass @nodes_or_number(1) def full_rary_tree(r, n) # r is a number. n can be a number of a list of nodes pass """ @decorator def _nodes_or_number(func_to_be_decorated, *args, **kw): # form tuple of arg positions to be converted. try: iter_wa = iter(which_args) except TypeError: iter_wa = (which_args,) # change each argument in turn new_args = list(args) for i in iter_wa: n = args[i] try: nodes = list(range(n)) except TypeError: nodes = tuple(n) else: if n < 0: msg = "Negative number of nodes not valid: {n}" raise nx.NetworkXError(msg) new_args[i] = (n, nodes) return func_to_be_decorated(*new_args, **kw) return _nodes_or_number
[docs]def preserve_random_state(func): """ Decorator to preserve the numpy.random state during a function. Parameters ---------- func : function function around which to preserve the random state. Returns ------- wrapper : function Function which wraps the input function by saving the state before calling the function and restoring the function afterward. Examples -------- Decorate functions like this:: @preserve_random_state def do_random_stuff(x, y): return x + y * numpy.random.random() Notes ----- If numpy.random is not importable, the state is not saved or restored. """ try: from numpy.random import get_state, seed, set_state @contextmanager def save_random_state(): state = get_state() try: yield finally: set_state(state) def wrapper(*args, **kwargs): with save_random_state(): seed(1234567890) return func(*args, **kwargs) wrapper.__name__ = func.__name__ return wrapper except ImportError: return func
[docs]def random_state(random_state_index): """Decorator to generate a numpy.random.RandomState instance. Argument position `random_state_index` is processed by create_random_state. The result is a numpy.random.RandomState instance. Parameters ---------- random_state_index : int Location of the random_state argument in args that is to be used to generate the numpy.random.RandomState instance. Even if the argument is a named positional argument (with a default value), you must specify its index as a positional argument. Returns ------- _random_state : function Function whose random_state keyword argument is a RandomState instance. Examples -------- Decorate functions like this:: @np_random_state(0) def random_float(random_state=None): return random_state.rand() @np_random_state(1) def random_array(dims, random_state=1): return random_state.rand(*dims) See Also -------- py_random_state """ @decorator def _random_state(func, *args, **kwargs): # Parse the decorator arguments. try: random_state_arg = args[random_state_index] except TypeError as e: raise nx.NetworkXError("random_state_index must be an integer") from e except IndexError as e: raise nx.NetworkXError("random_state_index is incorrect") from e # Create a numpy.random.RandomState instance random_state = create_random_state(random_state_arg) # args is a tuple, so we must convert to list before modifying it. new_args = list(args) new_args[random_state_index] = random_state return func(*new_args, **kwargs) return _random_state
np_random_state = random_state def py_random_state(random_state_index): """Decorator to generate a random.Random instance (or equiv). Argument position `random_state_index` processed by create_py_random_state. The result is either a random.Random instance, or numpy.random.RandomState instance with additional attributes to mimic basic methods of Random. Parameters ---------- random_state_index : int Location of the random_state argument in args that is to be used to generate the numpy.random.RandomState instance. Even if the argument is a named positional argument (with a default value), you must specify its index as a positional argument. Returns ------- _random_state : function Function whose random_state keyword argument is a RandomState instance. Examples -------- Decorate functions like this:: @py_random_state(0) def random_float(random_state=None): return random_state.rand() @py_random_state(1) def random_array(dims, random_state=1): return random_state.rand(*dims) See Also -------- np_random_state """ @decorator def _random_state(func, *args, **kwargs): # Parse the decorator arguments. try: random_state_arg = args[random_state_index] except TypeError as e: raise nx.NetworkXError("random_state_index must be an integer") from e except IndexError as e: raise nx.NetworkXError("random_state_index is incorrect") from e # Create a numpy.random.RandomState instance random_state = create_py_random_state(random_state_arg) # args is a tuple, so we must convert to list before modifying it. new_args = list(args) new_args[random_state_index] = random_state return func(*new_args, **kwargs) return _random_state