added 'mean' & 'last' functions

Equation/equation_base.py

@@ -72,6 +72,9 @@ def sumargs(*args):
     addUnaryOp('-',"-{0:s}","-{0:s}",op.neg)
     addFn('abs',"abs({0:s})","\\left|{0:s}\\right|",1,op.abs)
     addFn('sum',"sum({0:s})","\\sum\\left({0:s}\\right)",'+',sumargs)
+    def last_of_list(args):
+        return args[-1]
+    addFn('last',"min({0:s})","\\text{last}\\left({0:s}\\right)",'+',last_of_list)
     addFn('prod',"prod({0:s})","\\prod\\left({0:s}\\right)",'+',product)
     if has_numpy:
         addFn('floor',"floor({0:s})","\\lfloor {0:s} \\rfloor",1,np.floor)
@@ -83,6 +86,7 @@ def sumargs(*args):
         addFn('re',"re({0:s})","\\Re\\left({0:s}\\right)",1,np.real)
         addFn('im',"re({0:s})","\\Im\\left({0:s}\\right)",1,np.imag)
         addFn('sqrt',"sqrt({0:s})","\\sqrt{{{0:s}}}",1,np.sqrt)
+        addFn('mean',"mean({0:s})","\\text{mean}\\left({0:s}\\right)",'+',np.mean)
         addConst("pi",np.pi)
         addConst("e",np.e)
         addConst("Inf",np.Inf)
@@ -97,6 +101,9 @@ def sumargs(*args):
         addFn('re',"re({0:s})","\\Re\\left({0:s}\\right)",1,complex.real)
         addFn('im',"re({0:s})","\\Im\\left({0:s}\\right)",1,complex.imag)
         addFn('sqrt',"sqrt({0:s})","\\sqrt{{{0:s}}}",1,math.sqrt)
+        def mean(args):
+            return float(sum(args)) / len(args)
+        addFn('mean',"mean({0:s})","\\text{mean}\\left({0:s}\\right)",'+',mean)
         addConst("pi",math.pi)
         addConst("e",math.e)
         addConst("Inf",float("Inf"))

tests/test_Equation.py

@@ -457,6 +457,23 @@ def testCall(self):
     def tearDown(self):
         pass
 
+class TestLastEquation(unittest.TestCase):
+    def setUp(self):
+        self.fn = Expression("last(x)")
+
+    def testCall(self):
+        self.assertEqual(self.fn([1]), 1)
+        self.assertEqual(self.fn([1,2,8,4,5]),5)
+
+class TestMeanEquation(unittest.TestCase):
+    def setUp(self):
+        self.fn = Expression("mean(x)")
+
+    def testCall(self):
+        self.assertEqual(self.fn([42]), 42)
+        self.assertEqual(self.fn(42), 42)
+        self.assertEqual(self.fn([1,2,3,4,5]),3)
+
 class TestEqualsEquation(unittest.TestCase):
     def setUp(self):
         self.fn = Expression("x == y")