Merge pull request #408 from realpython/python-rounding-update

Add materials for Python Rounding tutorial

Author: KateFinegan

python-rounding/README.md

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+# How to Round Numbers in Python
+
+Here you can find code examples showing different rounding strategies as covered by the Real Python tutorial [How to Round Numbers in Python](https://realpython.com/python-rounding/).

python-rounding/rounding.py

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+import math
+
+
+def truncate(n, decimals=0):
+    multiplier = 10**decimals
+    return int(n * multiplier) / multiplier
+
+
+def round_up(n, decimals=0):
+    multiplier = 10**decimals
+    return math.ceil(n * multiplier) / multiplier
+
+
+def round_down(n, decimals=0):
+    multiplier = 10**decimals
+    return math.floor(n * multiplier) / multiplier
+
+
+def round_half_up(n, decimals=0):
+    multiplier = 10**decimals
+    return math.floor(n * multiplier + 0.5) / multiplier
+
+
+def round_half_down(n, decimals=0):
+    multiplier = 10**decimals
+    return math.ceil(n * multiplier - 0.5) / multiplier
+
+
+def round_half_away_from_zero(n, decimals=0):
+    rounded_abs = round_half_up(abs(n), decimals)
+    return math.copysign(rounded_abs, n)
+
+
+def round_half_to_even(n, decimals=0):
+    return round(n, ndigits=decimals)

python-rounding/rounding_numpy.py

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+import numpy as np
+
+
+def truncate(n, decimals=0):
+    multiplier = 10**decimals
+    return np.trunc(n * multiplier) / multiplier
+
+
+def round_up(n, decimals=0):
+    multiplier = 10**decimals
+    return np.ceil(n * multiplier) / multiplier
+
+
+def round_down(n, decimals=0):
+    multiplier = 10**decimals
+    return np.floor(n * multiplier) / multiplier
+
+
+def round_half_up(n, decimals=0):
+    multiplier = 10**decimals
+    return np.floor(n * multiplier + 0.5) / multiplier
+
+
+def round_half_down(n, decimals=0):
+    multiplier = 10**decimals
+    return np.ceil(n * multiplier - 0.5) / multiplier
+
+
+def round_half_away_from_zero(n, decimals=0):
+    rounded_abs = round_half_up(np.abs(n), decimals)
+    return np.copysign(rounded_abs, n)
+
+
+def round_half_to_even(n, decimals=0):
+    return np.round(n, decimals=decimals)