How to replace a letter with a corresponding number

ruby-talk
1

I am working through the Ruby Quiz website and I am already stuck on
number 1 - Solitaire Cypher.

I have a string, let's say "RUBYC ODEIS THEBE STXXX". I need to convert
each letter to its corresponding number (i.e., A=1, B=2, etc.).

I had hoped I could use gsub with a regexp like this:

coded_text = text.gsub(/[A-Z/,[1-26])

but that doesn't work. Any ideas?

···

--
Posted via http://www.ruby-forum.com/.

2

Hello,

You can do this task in steps below:
1. Create a hash contains character as key and its corresponding number as
value.
2. Use String#split to split the String into an array.
3. Use Array#collect to convert characters to corresponding number.

Example:

# Create hash contains alphabetical table
alpha_table = {}
(('A'..'Z').zip(1..26)).each { |x| alpha_table[x[0]] = x[1] }

s = "RUBYC" # String to convert
result = s.to_a.collect { |x| alpha_table }

···

On Wed, May 23, 2012 at 7:22 PM, Rich McMullen <lists@ruby-forum.com> wrote:

I am working through the Ruby Quiz website and I am already stuck on
number 1 - Solitaire Cypher.

I have a string, let's say "RUBYC ODEIS THEBE STXXX". I need to convert
each letter to its corresponding number (i.e., A=1, B=2, etc.).

I had hoped I could use gsub with a regexp like this:

coded_text = text.gsub(/[A-Z/,[1-26])

but that doesn't work. Any ideas?

--
Posted via http://www.ruby-forum.com/\.

Regards,

--
Duong Quang Ha (Hà Quang Dương in Vietnamese)
blog.haqduong.com

3

First of all you need to know if you have a formula to calculate the
corresponding number or you need a mapping.
In this case, each letter's ASCII value can be used:

1.9.2p290 :005 > "A".ord
=> 65

so for example, if you substract 64 from the ord of a char, you will
get 1 for A, 2 for B, etc.
Now for gsub to work you can use the block form, in which you will get
the matched part of the string, and the result of the block is the
replacement and try this:

text.gsub(/[A-Z]/) {|m| m.ord - 64}

1.9.2p290 :007 > text = "ABCDE"
=> "ABCDE"
1.9.2p290 :008 > text.gsub(/[A-Z]/) {|m| m.ord - 64}
=> "12345"

Hope this helps,

Jesus.

···

On Wed, May 23, 2012 at 2:22 PM, Rich McMullen <lists@ruby-forum.com> wrote:

I am working through the Ruby Quiz website and I am already stuck on
number 1 - Solitaire Cypher.

I have a string, let's say "RUBYC ODEIS THEBE STXXX". I need to convert
each letter to its corresponding number (i.e., A=1, B=2, etc.).

I had hoped I could use gsub with a regexp like this:

coded_text = text.gsub(/[A-Z/,[1-26])

but that doesn't work. Any ideas?

4

coded_text = text.gsub(/[A-Z/,[1-26])

try

s=("A".."Z").to_a.join

=> "ABCDEFGHIJKLMNOPQRSTUVWXYZ"

0> text="ABCDE"
=> "ABCDE"

text.gsub(/[A-Z]/){|c|s.index(c)+1}

=> "12345"

···

On Wed, May 23, 2012 at 8:22 PM, Rich McMullen <lists@ruby-forum.com> wrote:

5

Awesome! Thanks guys, I appreciate it.

···

--
Posted via http://www.ruby-forum.com/.

6

Hi,

I'm sorry, the last command must be:

result = s.split('').collect { |x| alpha_table }

···

On Wed, May 23, 2012 at 7:36 PM, Duong Quang Ha <quangduongha@gmail.com>wrote:

Hello,

You can do this task in steps below:
1. Create a hash contains character as key and its corresponding number as
value.
2. Use String#split to split the String into an array.
3. Use Array#collect to convert characters to corresponding number.

Example:

# Create hash contains alphabetical table
alpha_table = {}
(('A'..'Z').zip(1..26)).each { |x| alpha_table[x[0]] = x[1] }

s = "RUBYC" # String to convert
result = s.to_a.collect { |x| alpha_table }

On Wed, May 23, 2012 at 7:22 PM, Rich McMullen <lists@ruby-forum.com>wrote:

I am working through the Ruby Quiz website and I am already stuck on
number 1 - Solitaire Cypher.

I have a string, let's say "RUBYC ODEIS THEBE STXXX". I need to convert
each letter to its corresponding number (i.e., A=1, B=2, etc.).

I had hoped I could use gsub with a regexp like this:

coded_text = text.gsub(/[A-Z/,[1-26])

but that doesn't work. Any ideas?

--
Posted via http://www.ruby-forum.com/\.

Regards,

--
Duong Quang Ha (Hà Quang Dương in Vietnamese)
blog.haqduong.com

--
Duong Quang Ha (Hà Quang Dương in Vietnamese)
blog.haqduong.com