CALCUALTORSRSDSDSDS

python/calculators/binomial distribution.py

@@ -0,0 +1,15 @@
+import operator as op
+from functools import reduce
+
+def nCr(n, r):
+    r = min(r, n-r)
+    num = reduce(op.mul, range(n, n - r, -1), 1)
+    den = reduce(op.mul, range(1, r + 1), 1)
+    return num / den
+
+def binomial(x, n, p):
+    q = 1 - p
+
+    return nCr(n, x) * (p**x) * (q**(n-x))
+
+print(binomial(5, 100, 0.1))

python/calculators/pmcc.py

@@ -0,0 +1,19 @@
+from operator import mul
+import math
+
+def pmcc(x, y):
+    if len(x) != len(y):
+        raise Exception('List x must be of the same length as list y. List x is {0} values long, whereas list y is {1} values long.'.format(len(x), len(y)))
+
+    n = len(x)
+    xy = list(map(mul, x, y))
+    xsq = [z**2 for z in x]
+    ysq = [z**2 for z in y]
+
+    sxy = sum(xy) - ((sum(x) * sum(y)) / n)
+    sxx = sum(xsq) - ((sum(x)**2) / n)
+    syy = sum(ysq) - ((sum(y)**2) / n)
+
+    return sxy / math.sqrt(sxx * syy)
+
+print(pmcc([1,2,3,4,5], [5,3,8,7,12]))

python/calculators/quadratic nth term.py

@@ -3,18 +3,24 @@ import operator
 def diff(a):
 	return list(map(operator.sub, a[1:], a[:-1]))
 
+def formatNumber(x):
+	if x % 1 == 0:
+		return int(x)
+	else:
+		return x	
+
 sequence = [-0.5,1,4.5,10,17.5]
 row1 = diff(sequence)
 row2 = diff(row1)
 
-a = row2[0] / 2
-b = row1[0] - (3 * a)
-c = sequence[0] - a - b
+a = formatNumber(row2[0] / 2)
+b = formatNumber(row1[0] - (3 * a))
+c = formatNumber(sequence[0] - a - b)
 
 print('''
 a = {0}
-b = {1}
-c = {2}
+b = {2}
+c = {4}
 
-Equation: {0}n^2 + {1}n + {2}
-'''.format(a, b, c))
+Equation: {0}n²{1}{2}n{3}{4}
+'''.format(a, '+' if b >= 0 else '', b, '+' if c >= 0 else '', c))

python/calculators/srcc.py

@@ -0,0 +1,33 @@
+import numpy
+
+def rank(x):
+    y = x.sort()
+    print(y)
+    res = []
+    for i in x:
+        res.append(y.index(x[i]) + 1)
+    return res
+
+def spearman(a, b):
+    if len(a) != len(b):
+        print('Both datasets must be the same length!')
+        return undefined
+
+    n = len(a)
+
+    # rank set a
+    aranks = sorted(range(n), reverse=True, key=a.__getitem__)
+    print(aranks)
+
+    # rank set b
+    branks = rank(b)
+
+    # work out the difference between ranks
+    d = aranks - branks
+    d = d**2
+    d = numpy.sum(d)
+
+    # plug the values into the formula
+    return 1 - ((6*d) / (n**3 - n))
+
+print(spearman([1,2,3,5,4], [5,4,3,2,1]))

python/calculators/stdev.py

@@ -0,0 +1,10 @@
+import math
+
+def sd(x):
+    n = len(x)
+    mean = sum(x) / n
+    squared = [y ** 2 for y in x]
+
+    return math.sqrt(abs((sum(squared) / n) - (mean**2)))
+
+print(sd([135,230,132,323]))

readme.md

@@ -38,3 +38,7 @@ Here you can find a bunch of random work from my GCSE Computer Science class dum
     - [14 - Italy](python/pythonchallenge.com/14%20-%20Italy.py)
 - [Calculators](python/calculators)
     - [Quadratic nth Term](python/calculators/quadratic%20nth%20term.py)
+    - [Binomial Distribution](python/calculators/binomial%20distribution.py)
+    - [Pearson's Product-Moment Correlation Coefficient](python/calculators/pmcc.py)
+    - [Spearman's Rank Correlation Coefficient](python/calculators/srcc.py)
+    - [Standard Deviation](python/calculators/stdev.py)