add method maxBy

README.md

@@ -489,7 +489,7 @@ we will compare with str(a) and str(b).
 R.Max('A', None) # None, 'A' < 'None'
 ```
 
-- [ ] maxBy
+- [x] maxBy
 - [ ] mean
 - [ ] median
 - [ ] memoizeWith

ramda/__init__.py

@@ -78,6 +78,7 @@
 from .match import match
 from .mathMod import mathMod
 from .Max import Max
+from .maxBy import maxBy
 from .Min import Min
 from .modulo import modulo
 from .multiply import multiply

ramda/maxBy.py

@@ -0,0 +1,10 @@
+from .Max import Max
+from .private._curry3 import _curry3
+
+
+def inner_maxBy(f, a, b):
+  resultB = f(b)
+  return b if Max(f(a), resultB) == resultB else a
+
+
+maxBy = _curry3(inner_maxBy)

test/test_maxBy.py

@@ -0,0 +1,17 @@
+import unittest
+
+import ramda as R
+
+"""
+https://github.com/ramda/ramda/blob/master/test/maxBy.js
+"""
+
+
+class TestMaxBy(unittest.TestCase):
+  def test_returns_the_larger_value_as_determined_by_the_function(self):
+    self.assertEqual(-3, R.maxBy(lambda x: x * x, -3, 2))
+    self.assertEqual({'x': 5, 'y': 10}, R.maxBy(R.prop('x'), {'x': 3, 'y': 1}, {'x': 5, 'y': 10}))
+
+
+if __name__ == '__main__':
+  unittest.main()