Convert binary array to floating point decimal

ruby-talk
1

new to ruby here, looking for a little help

I'm trying to convert some C# code to ruby, however I'm not getting the
desired results
The code is supposed to convert a binary string to a floating point
number

public float binaryStringToFloat(int length)
{
   float result = 0;
   int num = 0;
   // form the integer number from the binary string
   for (int i = 0; i < length; i++)
      {
      num = num << 1;
      num = num + binaryArray[(length - i) - 1];
      }
   // scale to the floating point value
   result = (float)num;
   result = result / (1 << binaryArray.length/2);
   return result;
}

any help will be appreciated

2

new to ruby here, looking for a little help

I'm trying to convert some C# code to ruby, however I'm not getting the
desired results
The code is supposed to convert a binary string to a floating point
number

public float

(int length)

{
   float result = 0;
   int num = 0;
   // form the integer number from the binary string
   for (int i = 0; i < length; i++)
      {
      num = num << 1;
      num = num + binaryArray[(length - i) - 1];
      }
   // scale to the floating point value
   result = (float)num;
   result = result / (1 << binaryArray.length/2);
   return result;
}

any help will be appreciated

Ruby has a built in method for converting a binary string into an
integer, so your code is simply

def binaryStringToFloat(str)
  str.to_i(2) * 1.0/str.length
end

but if you want to translate your algorithm literally:

def binaryStringToFloat(str)
  num = 0
  # reverse the string, split it into characters, then iterate over
the characters
  str.reverse.split(//).each {|digit|
    num = (num << 1) + digit.to_i # << has lower precedence than +
  }

  return num * 1.0 / (1 << str.length)
end

also, the pattern

accumulator = start_val
collection.each {|element|
  accumulator = f(accumulator, element)
}

is captured by the inject method, so we can replace the "each" loop with

num = str.reverse.split(//).inject(0) {|sum, digit| (sum << 1) + digit .to_i}

martin

···

On 12/3/06, Nebiru <Nebiru@gmail.com> wrote:

3

Wow, so much learned in one post...thank you

Martin DeMello wrote:

···

On 12/3/06, Nebiru <Nebiru@gmail.com> wrote:
> new to ruby here, looking for a little help
>
> I'm trying to convert some C# code to ruby, however I'm not getting the
> desired results
> The code is supposed to convert a binary string to a floating point
> number
>
> public float
(int length)
> {
> float result = 0;
> int num = 0;
> // form the integer number from the binary string
> for (int i = 0; i < length; i++)
> {
> num = num << 1;
> num = num + binaryArray[(length - i) - 1];
> }
> // scale to the floating point value
> result = (float)num;
> result = result / (1 << binaryArray.length/2);
> return result;
> }
>
> any help will be appreciated

Ruby has a built in method for converting a binary string into an
integer, so your code is simply

def binaryStringToFloat(str)
  str.to_i(2) * 1.0/str.length
end

but if you want to translate your algorithm literally:

def binaryStringToFloat(str)
  num = 0
  # reverse the string, split it into characters, then iterate over
the characters
  str.reverse.split(//).each {|digit|
    num = (num << 1) + digit.to_i # << has lower precedence than +
  }

  return num * 1.0 / (1 << str.length)
end

also, the pattern

accumulator = start_val
collection.each {|element|
  accumulator = f(accumulator, element)
}

is captured by the inject method, so we can replace the "each" loop with

num = str.reverse.split(//).inject(0) {|sum, digit| (sum << 1) + digit .to_i}

martin

4

that should be

str.to_i(2) * 1.0/(1 << str.length)

of course

martin

···

On 12/3/06, Martin DeMello <martindemello@gmail.com> wrote:

Ruby has a built in method for converting a binary string into an
integer, so your code is simply

def binaryStringToFloat(str)
  str.to_i(2) * 1.0/str.length
end