refractor: removed unnecessary comment

README.md

@@ -26,3 +26,4 @@ Repository for CDS-2020 Programming and Promt Engineering II
 |Thinkful - Object Drills: Quarks|kata_thinkful_quarks.py|test_thinkful_quarks.py|[5882b052bdeafec15e0000e6](https://www.codewars.com/kata/5882b052bdeafec15e0000e6)|
 |Thinkful - Object Drills: Vectors|kata_thinkful_vectors.py|test_thinkful_vectors.py|[587f1e1f39d444cee6000ad4](https://www.codewars.com/kata/587f1e1f39d444cee6000ad4)|
 |Building blocks|kata_building_blocks.py|test_building_blocks.py|[55b75fcf67e558d3750000a3](https://www.codewars.com/kata/55b75fcf67e558d3750000a3)|
+|PaginationHelper|kata_pagination_helper.py|test_pagination_helper.py|[515bb423de843ea99400000a](https://www.codewars.com/kata/515bb423de843ea99400000a)|

src/codewars/kata_pagination_helper.py

@@ -0,0 +1,46 @@
+class PaginationHelper:
+
+    # The constructor takes in an array of items and an integer indicating
+    # how many items fit within a single page
+    def __init__(self, collection, items_per_page):
+        self.collection = collection
+        self.items_per_page = items_per_page
+
+    # returns the number of items within the entire collection
+    def item_count(self):
+        return len(self.collection)
+
+    # returns the number of pages
+    def page_count(self):
+        return int(len(self.collection) / self.items_per_page) + (
+            len(self.collection) % self.items_per_page > 0
+        )
+
+    # returns the number of items on the given page. page_index is zero based
+    # this method should return -1 for page_index values that are out of range
+    def page_item_count(self, page_index):
+        if page_index < 0 or self.page_count() - 1 < page_index:
+            return -1
+
+        if page_index == 0:
+            return len(self.collection[: self.items_per_page])
+
+        return len(
+            self.collection[
+                self.items_per_page * page_index : self.items_per_page * page_index
+                + self.items_per_page
+            ]
+        )
+
+    # determines what page an item at the given index is on. Zero based indexes.
+    # this method should return -1 for item_index values that are out of range
+    def page_index(self, item_index):
+        try:
+            self.collection[item_index]
+
+            if item_index < 0:
+                raise IndexError
+        except IndexError:
+            return -1
+
+        return item_index // self.items_per_page

tests/codewars/test_pagination_helper.py

@@ -0,0 +1,27 @@
+from src.codewars.kata_pagination_helper import PaginationHelper
+
+
+def test_pagination():
+    collection = ["a", "b", "c", "d", "e", "f"]
+    helper = PaginationHelper(collection, 4)
+
+    assert helper.page_count() == 2
+    assert helper.item_count() == 6
+    assert helper.page_item_count(0) == 4
+    assert helper.page_item_count(1) == 2
+    assert helper.page_item_count(2) == -1
+    assert helper.page_index(5) == 1
+    assert helper.page_index(2) == 0
+    assert helper.page_index(20) == -1
+    assert helper.page_index(-10) == -1
+
+    empty = PaginationHelper([], 10)
+
+    assert empty.item_count() == 0
+    assert empty.page_count() == 0
+    assert empty.page_index(0) == -1
+    assert empty.page_index(1) == -1
+    assert empty.page_index(-1) == -1
+    assert empty.page_item_count(0) == -1
+    assert empty.page_item_count(1) == -1
+    assert empty.page_item_count(-1) == -1