Module: Molecules::Utils

Included in:
EmpiricalFormula
Defined in:
lib/molecules/utils.rb

Overview

A number of utility routines used by EmpiricalFormula and elsewhere. These methods are used a great deal and are all prime candidates for optimization (for example using RubyInline).

Class Method Summary collapse

Class Method Details

.add(a, b, n = 1) ⇒ Object

Adds the elements of b to a at corresponding indicies, multiplying by n. The input arrays do not have to be the same length. Returns a with trailing zeros removed.



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# File 'lib/molecules/utils.rb', line 19

def add(a, b, n=1)
  a << 0 while a.length < b.length
  
  # oddly, this is faster than each_with_index
  i = 0
  b.each do |factor|
    a[i] += n * factor
    i += 1
  end
  
  a.pop while a[-1] == 0
  a
end

.count(str, patterns) ⇒ Object

Collects the number of each of the patterns in str. For example:

count("abcabca", ["a", "b", "c"])  # => [3, 2, 2]
count("abcabca", ["a", "bc"])      # => [3, 4]



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# File 'lib/molecules/utils.rb', line 44

def count(str, patterns)
  patterns.collect {|pattern| str.count(pattern)}
end

.multiply(a, factor) ⇒ Object

Multiples the elements of array a by factor, returning a. Clears a if factor == 0.



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# File 'lib/molecules/utils.rb', line 35

def multiply(a, factor)
  factor == 0 ? a.clear : a.collect! {|i| i * factor}
end

.round(n, precision) ⇒ Object

Rounds n to the specified precision (ie number of decimal places)



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# File 'lib/molecules/utils.rb', line 10

def round(n, precision)
  factor = 10**precision.to_i
  (n * factor).round.to_f / factor
end