Class: Array

Inherits:
Object
  • Object
show all
Defined in:
lib/easystats.rb

Instance Method Summary collapse

Instance Method Details

#mean ⇒ Object Also known as: average

take in an array of numbers and calculate the mean (average)



3
4
5
6
7
 
# File 'lib/easystats.rb', line 3

def mean
  return unless self.any?

  self.sum / self.count.to_f
end

#median ⇒ Object

take in the array of numbers and calculate the median



12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
 
# File 'lib/easystats.rb', line 12

def median
  return unless self.any?

  data = self

  halfway = data.count / 2

  # Sort the array
  data = data.sort

  # The median will be different based on the number of numbers in the array
  # If there is an even number in the array
  if(data.count % 2) == 0
    median = (data[halfway] + data[halfway-1]) / 2.0

  # Else, there is an odd number of elements in the array
  else
    median = data[halfway]
  end

  median
end

#mode ⇒ Object

take in an array of numbers and return the mode



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
 
# File 'lib/easystats.rb', line 36

def mode
  return unless self.any?

  # Sort the array
  data = self.sort

  # create a flag to tell the user if all the numbers only appear once
  no_mode = true

  # The variable that will hold the highest number
  highest_value = 0

  # The variable that holds the most time the value appears
  most_times = 0

  # Create a new hash to hold the numbers
  tmp = Hash.new

  # Populate the hash
  data.each do |num|
    if tmp["#{num}"].nil? == false
      tmp["#{num}"] = tmp["#{num}"].to_i + 1
    else
      tmp["#{num}"] = 1
    end
  end

  # Check to make sure that there is a mode
  data.each do |num|
    if tmp["#{num}"].to_i > 0
      no_mode = false
    end
  end

  if no_mode == true
    nil
  else
    data.each do |num|
      if tmp["#{num}"].to_i > most_times
        highest_value = num
        most_times = tmp["#{num}"]
      end
    end

    # now loop through again just to make sure another number doesn't appear an equal number of times
    data.each do |num|
      if num != highest_value
        if tmp["#{num}"].to_i == most_times
          no_mode = true
        end
      end
    end

    if no_mode == true
      nil
    else
      highest_value
    end
  end
end

#range ⇒ Object

take in an array of numbers and calculate the range



98
99
100
101
102
103
 
# File 'lib/easystats.rb', line 98

def range
  return unless self.any?

  data = self.sort
  data.last - data.first
end

#standard_deviation ⇒ Object

take in an array of numbers and calculate the standard deviation



106
107
108
109
110
111
 
# File 'lib/easystats.rb', line 106

def standard_deviation
  return unless self.any?
  return 0 if self.one?

  Math::sqrt(self.sum_of_deviations_squared / (self.count-1))
end

#sum ⇒ Object

take in an array of numbers and calculate the sum



114
115
116
 
# File 'lib/easystats.rb', line 114

def sum
  self.reduce { |total, number| total + number }
end

#variance ⇒ Object 



118
119
120
121
122
 
# File 'lib/easystats.rb', line 118

def variance
  return unless self.any?

  self.sum_of_deviations_squared / self.count.to_f
end