Replace itertools.tee with list

Author: mariosasko

torch/optim/sparse_adam.py

@@ -1,4 +1,3 @@
-import itertools
 import math
 import torch
 from .optimizer import Optimizer
@@ -33,12 +32,10 @@ def __init__(self, params, lr=1e-3, betas=(0.9, 0.999), eps=1e-8):
         if not 0.0 <= betas[1] < 1.0:
             raise ValueError("Invalid beta parameter at index 1: {}".format(betas[1]))
 
-        # if params are in the form of a generator, the next for-loop exhausts it,
-        # so the copy is passed to the loop
-        params, params_copy = itertools.tee(params)
+        params = list(params)
 
         sparse_params = []
-        for index, param in enumerate(params_copy):
+        for index, param in enumerate(params):
             if isinstance(param, dict):
                 for d_index, d_param in enumerate(param.get("params", [])):
                     if d_param.is_sparse: