Python 3.5 and 3.6 compatibility.

arviz-devs · Mar 27, 2021 · 6d27fd5 · 6d27fd5
1 parent 7eb162c
commit 6d27fd5
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Showing 2 changed files with 31 additions and 11 deletions.
diff --git a/arviz/rcparams.py b/arviz/rcparams.py
@@ -9,7 +9,14 @@
 from collections.abc import MutableMapping
 from pathlib import Path
 from typing import Any, Dict
-from typing_extensions import Literal, get_args
+from typing_extensions import Literal
+
+NO_GET_ARGS: bool = False
+try:
+    from typing_extensions import get_args
+except ImportError:
+    NO_GET_ARGS = True
+
 
 import numpy as np
 
@@ -281,9 +288,17 @@ def validate_iterable(value):
     "plot.matplotlib.constrained_layout": (True, _validate_boolean),
     "plot.matplotlib.show": (False, _validate_boolean),
     "stats.hdi_prob": (0.94, _validate_probability),
-    "stats.information_criterion": ("loo", _make_validate_choice(set(get_args(ICKeyword)))),
+    "stats.information_criterion": (
+        "loo",
+        _make_validate_choice({"loo", "waic"} if NO_GET_ARGS else set(get_args(ICKeyword))),
+    ),
     "stats.ic_pointwise": (False, _validate_boolean),
-    "stats.ic_scale": ("log", _make_validate_choice(set(get_args(ScaleKeyword)))),
+    "stats.ic_scale": (
+        "log",
+        _make_validate_choice(
+            {"log", "negative_log", "deviance"} if NO_GET_ARGS else set(get_args(ScaleKeyword))
+        ),
+    ),
     "stats.ic_compare_method": (
         "stacking",
         _make_validate_choice({"stacking", "bb-pseudo-bma", "pseudo-bma"}),

diff --git a/arviz/stats/stats.py b/arviz/stats/stats.py
@@ -9,7 +9,13 @@
 import scipy.stats as st
 import xarray as xr
 from scipy.optimize import minimize
-from typing_extensions import Literal, get_args
+from typing_extensions import Literal
+
+NO_GET_ARGS: bool = False
+try:
+    from typing_extensions import get_args
+except ImportError:
+    NO_GET_ARGS = True
 
 from arviz import _log
 from ..data import InferenceData, convert_to_dataset, convert_to_inference_data
@@ -156,12 +162,10 @@ def compare(
         scale = cast(ScaleKeyword, scale.lower())
     else:
         scale = cast(ScaleKeyword, rcParams["stats.ic_scale"])
-    if scale not in get_args(ScaleKeyword):
-        raise ValueError(
-            f"{scale} is not a valid value for scale: must be in {get_args(ScaleKeyword)}"
-        )
+    allowable = ["log", "negative_log", "deviance"] if NO_GET_ARGS else get_args(ScaleKeyword)
+    if scale not in allowable:
+        raise ValueError(f"{scale} is not a valid value for scale: must be in {allowable}")
 
-    assert scale in get_args(ScaleKeyword)
     if scale == "log":
         scale_value = 1
         ascending = False
@@ -176,8 +180,9 @@ def compare(
         ic = cast(ICKeyword, rcParams["stats.information_criterion"])
     else:
         ic = cast(ICKeyword, ic.lower())
-    if ic not in get_args(ICKeyword):
-        raise ValueError(f"{ic} is not a valid value for ic: must be in {get_args(ICKeyword)}")
+    allowable = ["loo", "waic"] if NO_GET_ARGS else get_args(ICKeyword)
+    if ic not in allowable:
+        raise ValueError(f"{ic} is not a valid value for ic: must be in {allowable}")
     if ic == "loo":
         ic_func: Callable = loo
         df_comp = pd.DataFrame(