1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
|
# TODO increase speed with vectors, matrices?
class Array
# Sum the size of single arrays in an array of arrays
# @param [Array] Array of arrays
# @return [Integer] Sum of size of array elements
def sum_size
self.inject(0) { |s,a|
if a.respond_to?('size')
s+=a.size
else
internal_server_error "No size available: #{a.inspect}"
end
}
end
# Check if the array has just one unique value.
# @param [Array] Array to test.
# @return [TrueClass,FalseClass]
def zero_variance?
return self.uniq.size == 1
end
# Get the median of an array
# @return [Numeric]
def median
sorted = self.sort
len = sorted.length
(sorted[(len - 1) / 2] + sorted[len / 2]) / 2.0
end
# Get the mean of an array
# @return [Numeric]
def mean
self.compact.inject{ |sum, el| sum + el }.to_f / self.compact.size
end
# Get the variance of an array
# @return [Numeric]
def sample_variance
m = self.mean
sum = self.compact.inject(0){|accum, i| accum +(i-m)**2 }
sum/(self.compact.length - 1).to_f
end
# Get the standard deviation of an array
# @return [Numeric]
def standard_deviation
Math.sqrt(self.sample_variance)
end
# Calculate dot product
# @param [Array]
# @return [Numeric]
def dot_product(a)
products = self.zip(a).map{|a, b| a * b}
products.inject(0) {|s,p| s + p}
end
# Calculate magnitude
# @return [Numeric]
def magnitude
squares = self.map{|x| x ** 2}
Math.sqrt(squares.inject(0) {|s, c| s + c})
end
# Convert array values for R
# @return [Array]
def for_R
if self.first.is_a?(String)
#"\"#{self.collect{|v| v.sub('[','').sub(']','')}.join(" ")}\"" # quote and remove square brackets
"NA"
else
self.median
end
end
def remove indices
out = self
indices.sort.reverse_each do |i|
out.delete_at i
end
out
end
# Correlation coefficient
# @param [Array]
# @return [Numeric]
def r(y)
raise "Argument is not a Array class!" unless y.class == Array
raise "Self array is nil!" if self.size == 0
raise "Argument array size is invalid!" unless self.size == y.size
mean_x = self.inject(0) { |s, a| s += a } / self.size.to_f
mean_y = y.inject(0) { |s, a| s += a } / y.size.to_f
cov = self.zip(y).inject(0) { |s, a| s += (a[0] - mean_x) * (a[1] - mean_y) }
var_x = self.inject(0) { |s, a| s += (a - mean_x) ** 2 }
var_y = y.inject(0) { |s, a| s += (a - mean_y) ** 2 }
r = cov / Math.sqrt(var_x)
r /= Math.sqrt(var_y)
end
end
|