import ast
import json
import importlib
from hashlib import md5
from itertools import tee, chain
def dict_hash(dct):
"""Return a hash of the contents of a dictionary"""
dct_s = json.dumps(dct, sort_keys=True)
try:
m = md5(dct_s)
except TypeError:
m = md5(dct_s.encode())
return m.hexdigest()
def exec_then_eval(code, namespace=None):
"""Exec a code block & return evaluation of the last line"""
# TODO: make this less brittle.
namespace = namespace or {}
block = ast.parse(code, mode='exec')
last = ast.Expression(block.body.pop().value)
exec(compile(block, '<string>', mode='exec'), namespace)
return eval(compile(last, '<string>', mode='eval'), namespace)
def import_obj(clsname, default_module=None):
"""
Import the object given by clsname.
If default_module is specified, import from this module.
"""
if default_module is not None:
if not clsname.startswith(default_module + '.'):
clsname = '{0}.{1}'.format(default_module, clsname)
mod, clsname = clsname.rsplit('.', 1)
mod = importlib.import_module(mod)
try:
obj = getattr(mod, clsname)
except AttributeError:
raise ImportError('Cannot import {0} from {1}'.format(clsname, mod))
return obj
def strip_vl_extension(filename):
"""Strip the vega-lite extension (either vl.json or json) from filename"""
for ext in ['.vl.json', '.json']:
if filename.endswith(ext):
return filename[:-len(ext)]
else:
return filename
def prev_this_next(it, sentinel=None):
"""Utility to return (prev, this, next) tuples from an iterator"""
i1, i2, i3 = tee(it, 3)
next(i3, None)
return zip(chain([sentinel], i1), i2, chain(i3, [sentinel]))
