Function subs

dask/core.py:323–359

Perform a substitution on a task Examples -------- >>> def inc(x): ... return x + 1 >>> subs((inc, 'x'), 'x', 1) # doctest: +ELLIPSIS ( , 1)

(task, key, val)

def subs(task, key, val):
    """Perform a substitution on a task

    Examples
    --------
    >>> def inc(x):
    ...     return x + 1

    >>> subs((inc, 'x'), 'x', 1)  # doctest: +ELLIPSIS
    (<function inc at ...>, 1)
    """
    type_task = type(task)
    if not (type_task is tuple and task and callable(task[0])):  # istask(task):
        try:
            if type_task is type(key) and task == key:
                return val
        except Exception:
            pass
        if type_task is list:
            return [subs(x, key, val) for x in task]
        return task
    newargs = []
    hash_key = {key}
    for arg in task[1:]:
        type_arg = type(arg)
        if type_arg is tuple and arg and callable(arg[0]):  # istask(task):
            arg = subs(arg, key, val)
        elif type_arg is list:
            arg = [subs(x, key, val) for x in arg]
        else:
            try:
                if arg in hash_key:  # Hash and equality match
                    arg = val
            except TypeError:  # not hashable
                pass
        newargs.append(arg)
    return task[:1] + tuple(newargs)


def _toposort(dsk, keys=None, returncycle=False, dependencies=None):