Align columns: Difference between revisions
added Scheme example
(→{{header|Elixir}}: String.ljust -> pad_trailing) |
(added Scheme example) |
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Line 5,888:
val padded = words map ( _.zipWithIndex.map{case(s,i)=>pad(s,maxlens(i),"center")+" "} )
padded map (_.reduceLeft(_ + _)) foreach println</lang>
=={{header|Scheme}}==
<lang scheme>
(import (scheme base)
(scheme write)
(srfi 1)
(except (srfi 13) string-for-each string-map)
(srfi 14))
;; text is a list of lines, alignment is left/right/center
;; displays the aligned text in columns with a single space gap
(define (align-columns text alignment)
(define (split line) ; splits string on $ into list of strings
(string-tokenize line (char-set-complement (->char-set "$"))))
(define (extend lst n) ; extends list to length n, by adding "" to end
(append lst (make-list (- n (length lst)) "")))
(define (align-word word width) ; align single word to fit width
(case alignment
((left) (string-pad-right word width))
((right) (string-pad word width))
((center) (let ((rem (- width (string-length word))))
(string-pad-right (string-pad word (- width (truncate (/ rem 2))))
width)))))
;
(display alignment) (newline)
(let* ((text-list (map split text))
(max-line-len (fold (lambda (text val) (max (length text) val)) 0 text-list))
(text-lines (map (lambda (line) (extend line max-line-len)) text-list))
(min-col-widths (map (lambda (col)
(fold (lambda (line val)
(max (string-length (list-ref line col))
val))
0
text-lines))
(iota max-line-len))))
(map (lambda (line)
(map (lambda (word width)
(display (string-append (align-word word width)
" ")))
line min-col-widths)
(newline))
text-lines))
(newline))
;; show example
(define *example*
'("Given$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."))
(align-columns *example* 'left)
(align-columns *example* 'center)
(align-columns *example* 'right)
</lang>
{{out}}
<pre>
left
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
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
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>
=={{header|sed}}==
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