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Align columns: Difference between revisions
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Further, allow for each word in a column to be either left
justified, right justified, or center justified within its column. </pre>
=={{header|Ruby}}==
<ruby>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
J2justifier = {'L' => String.instance_method(:ljust),
'R' => String.instance_method(:rjust),
'C' => String.instance_method(: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 L, R, or C; (Left, Right, or Centered).
Return the justified output as a string
=end
def aligner(infile, justification = 'L')
justifier = J2justifier[justification]
fieldsbyrecord = infile.map {|line| line.strip.split('$')}
# pad to same number of fields per record
maxfields = fieldsbyrecord.map {|record| record.length}.max
fieldsbyrecord = fieldsbyrecord.map {|fields|
fields + ['']*(maxfields - fields.length)
}
# rotate
fieldsbycolumn = fieldsbyrecord.transpose
# calculate max fieldwidth per column
colwidths = fieldsbycolumn.map {|column|
column.map {|field| field.length}.max
}
# pad fields in columns to colwidth with spaces
fieldsbycolumn = colwidths.zip(fieldsbycolumn).map {|width, column|
column.map {|field| justifier.bind(field).call(width)}
}
# rotate again
fieldsbyrecord = fieldsbycolumn.transpose
fieldsbyrecord.map {|record| record.join(" ")}.join("\n")
end
for align in %w{Left Right Center}
infile = StringIO.new(textinfile)
puts "\n# %s Column-aligned output:" % align
puts aligner(infile, align[0..0])
end</ruby>
Example output:
<pre>
# Left Column-aligned output:
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.
# Right Column-aligned output:
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.
# Center Column-aligned output:
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.
</pre>
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