Chunking bug fix (#265)

* Ensure mpid can be pulled from static calcs

* Linting

* Fix prechunking on materials and thermo

* Ensure -N arg is passed to prechunk properly

emmet-builders/emmet/builders/vasp/materials.py

@@ -1,5 +1,6 @@
 from datetime import datetime
 from itertools import chain
+from math import ceil
 from typing import Dict, Iterable, Iterator, List, Optional
 
 from maggma.builders import Builder
@@ -107,7 +108,10 @@ def prechunk(self, number_splits: int) -> Iterable[Dict]:
             if d[self.tasks.key] in to_process_tasks
         }
 
-        for formula_chunk in grouper(to_process_forms, number_splits):
+        N = ceil(len(to_process_forms) / number_splits)
+
+        for formula_chunk in grouper(to_process_forms, N):
+
             yield {"query": {"formula_pretty": {"$in": list(formula_chunk)}}}
 
     def get_items(self) -> Iterator[List[Dict]]:

emmet-builders/emmet/builders/vasp/thermo.py

@@ -2,6 +2,7 @@
 from collections import defaultdict
 from itertools import chain
 from typing import Dict, Iterable, Iterator, List, Optional, Set
+from math import ceil
 
 from maggma.core import Builder, Store
 from maggma.utils import grouper
@@ -82,7 +83,10 @@ def prechunk(self, number_splits: int) -> Iterable[Dict]:
             if chemsys not in to_process_chemsys:
                 to_process_chemsys |= chemsys_permutations(chemsys)
 
-        for chemsys_chunk in grouper(to_process_chemsys, number_splits):
+        N = ceil(len(to_process_chemsys) / number_splits)
+
+        for chemsys_chunk in grouper(to_process_chemsys, N):
+
             yield {"query": {"chemsys": {"$in": list(chemsys_chunk)}}}
 
     def get_items(self) -> Iterator[List[Dict]]: