Method columnize

Lib/cmd.py:359–414

Display a list of strings as a compact set of columns. Each column is only as wide as necessary. Columns are separated by two spaces (one was not legible enough).

(self, list, displaywidth=80)

            self.stdout.write("\n")

    def columnize(self, list, displaywidth=80):
        """Display a list of strings as a compact set of columns.

        Each column is only as wide as necessary.
        Columns are separated by two spaces (one was not legible enough).
        """
        if not list:
            self.stdout.write("<empty>\n")
            return

        nonstrings = [i for i in range(len(list))
                        if not isinstance(list[i], str)]
        if nonstrings:
            raise TypeError("list[i] not a string for i in %s"
                            % ", ".join(map(str, nonstrings)))
        size = len(list)
        if size == 1:
            self.stdout.write('%s\n'%str(list[0]))
            return
        # Try every row count from 1 upwards
        for nrows in range(1, len(list)):
            ncols = (size+nrows-1) // nrows
            colwidths = []
            totwidth = -2
            for col in range(ncols):
                colwidth = 0
                for row in range(nrows):
                    i = row + nrows*col
                    if i >= size:
                        break
                    x = list[i]
                    colwidth = max(colwidth, len(x))
                colwidths.append(colwidth)
                totwidth += colwidth + 2
                if totwidth > displaywidth:
                    break
            if totwidth <= displaywidth:
                break
        else:
            nrows = len(list)
            ncols = 1
            colwidths = [0]
        for row in range(nrows):
            texts = []
            for col in range(ncols):
                i = row + nrows*col
                if i >= size:
                    x = ""
                else:
                    x = list[i]
                texts.append(x)
            while texts and not texts[-1]:
                del texts[-1]
            for col in range(len(texts)):
                texts[col] = texts[col].ljust(colwidths[col])
            self.stdout.write("%s\n"%str("  ".join(texts)))