Align columns: Difference between revisions

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=={{header|Ruby}}==

<lang ruby>~~require~~ '~~stringio~~'

<lang ruby>J2justifier = {'L' => :ljust,

'R' => :rjust,

'C' => :center}

textinfile = <<END

Given$a$text$file$of$many$lines,$where$fields$within$a$line$

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are$delineated$by$a$single$'dollar'$character,$write$a$program

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that$aligns$each$column$of$fields$by$ensuring$that$words$in$each$

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column$are$separated$by$at$least$one$space.

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Further,$allow$for$each$word$in$a$column$to$be$either$left$

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justified,$right$justified,$or$center$justified$within$its$column.

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END

J2justifier = {'L' => String.instance_method(:ljust),

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'R' => ~~String.instance_method(~~:rjust),

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'C' => ~~String.instance_method(~~:center)}

=begin

Justify columns of textual tabular input where the record separator is the newline

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=end

def aligner(infile, justification = 'L')

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justifier = J2justifier[justification]

fieldsbyrow = infile.map {|line| line.strip.split('$')}

# pad to same number of fields per record

maxfields = fieldsbyrow.map ~~{|row| row.~~length}.max

maxfields = fieldsbyrow.map(&:length).max

fieldsbyrow.map! {|row|

fieldsbyrow.map! {|row| row + ['']*(maxfields - row.length)}

row + ['']*(maxfields - row.length)

}

# calculate max fieldwidth per column

colwidths = fieldsbyrow.transpose.map {|column|

column.map ~~{|field| field.~~length}.max

column.map(&:length).max

}

# pad fields in columns to colwidth with spaces

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justifier = J2justifier[justification]

fieldsbyrow.map! {|row|

fieldsbyrow.map {|row|

row.zip(colwidths).map {|field, width|

~~justifier~~.~~bind~~(~~field)[~~width]

field.send(justifier, width)

}

}.join(" ")

}

}.join("\n")

fieldsbyrow.map {|row| row.join(" ")}.join("\n")

end

require 'stringio'

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