Initial data commit

Task/Align-columns/Python/align-columns-2.py

@@ -0,0 +1,45 @@
+from StringIO import StringIO
+
+textinfile = '''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.'''
+
+j2justifier = dict(L=str.ljust, R=str.rjust, C=str.center)
+
+def aligner(infile, justification = 'L'):
+  ''' \
+  Justify columns of textual tabular input where the row 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
+  '''
+  assert justification in j2justifier, "justification can be L, R, or C; (Left, Right, or Centered)."
+  justifier = j2justifier[justification]
+
+  fieldsbyrow= [line.strip().split('$') for line in infile]
+  # pad to same number of fields per row
+  maxfields = max(len(row) for row in fieldsbyrow)
+  fieldsbyrow = [fields + ['']*(maxfields - len(fields))
+                    for fields in fieldsbyrow]
+  # rotate
+  fieldsbycolumn = zip(*fieldsbyrow)
+  # calculate max fieldwidth per column
+  colwidths = [max(len(field) for field in column)
+               for column in fieldsbycolumn]
+  # pad fields in columns to colwidth with spaces
+  fieldsbycolumn = [ [justifier(field, width) for field in column]
+                     for width, column in zip(colwidths, fieldsbycolumn) ]
+  # rotate again
+  fieldsbyrow = zip(*fieldsbycolumn)
+
+  return "\n".join( " ".join(row) for row in fieldsbyrow)
+
+
+for align in 'Left Right Center'.split():
+  infile = StringIO(textinfile)
+  print "\n# %s Column-aligned output:" % align
+  print aligner(infile, align[0])