Step by Step solution about How to resolve the algorithm Align columns step by step in the Ruby programming language

The provided Ruby code defines a method called aligner that is used to justify columns of textual tabular input based on a specified justification option. Here's a step-by-step explanation of how the code works:

1. Input Handling:

   • The aligner method takes two parameters: infile (an input stream or string containing the tabular data) and justification (an optional symbol specifying the justification option, which can be :Left, :Right, or :Center). If justification is not provided, it defaults to :Left.

2. Data Processing:

   • The input data is first split into rows, with each row containing an array of fields separated by the dollar ($) character.
   • The code then ensures that all rows have the same number of fields by padding with empty strings to make the data consistent.
   • Next, the code calculates the maximum field width for each column. The maximum field width is determined by finding the longest field in each column of the input data.
   • The fields in each column are then padded with spaces to match the calculated field width. The justification method (ljust, rjust, or center) is used to justify the fields within each column based on the specified justification option.

3. Output Generation:

   • The resulting justified columns are joined together with spaces to form each row, and the rows are joined with newlines to form the final output string.

4. Usage:

   • The code demonstrates the usage of the aligner method by reading a sample textual input from a string and aligning its columns for different justification options (:Left, :Right, and :Center). The aligned output is then printed for each justification option.

The J2justifier hash is used to map the justification symbols (:Left, :Right, :Center) to the corresponding justification methods (:ljust, :rjust, :center) that are used to justify the fields within each column.

Overall, this code provides a way to align the columns of tabular data based on a specified justification option, ensuring that words in each column are separated by at least one space.

J2justifier = {Left: :ljust, Right: :rjust, Center: :center}

=begin
Justify columns of textual tabular input where the record separator is the newline
and the field separator is a 'dollar' character.
justification can be Symbol; (:Left, :Right, or :Center).

Return the justified output as a string
=end
def aligner(infile, justification = :Left)
  fieldsbyrow = infile.map {|line| line.strip.split('$')}
  # pad to same number of fields per record
  maxfields = fieldsbyrow.map(&:length).max
  fieldsbyrow.map! {|row| row + ['']*(maxfields - row.length)}
  # calculate max fieldwidth per column
  colwidths = fieldsbyrow.transpose.map {|column|
    column.map(&:length).max
  }
  # pad fields in columns to colwidth with spaces
  justifier = J2justifier[justification]
  fieldsbyrow.map {|row|
    row.zip(colwidths).map {|field, width|
      field.send(justifier, width)
    }.join(" ")
  }.join("\n")
end

require 'stringio'

textinfile = <<END
Given$a$text$file$of$many$lines,$where$fields$within$a$line$
are$delineated$by$a$single$'dollar'$character,$write$a$program
that$aligns$each$column$of$fields$by$ensuring$that$words$in$each$
column$are$separated$by$at$least$one$space.
Further,$allow$for$each$word$in$a$column$to$be$either$left$
justified,$right$justified,$or$center$justified$within$its$column.
END

for align in [:Left, :Right, :Center]
  infile = StringIO.new(textinfile)
  puts "\n# %s Column-aligned output:" % align
  puts aligner(infile, align)
end