How to print a list more nicely?

Question

This is similar to How to print a list in Python “nicely”, but I would like to print the list even more nicely -- without the brackets and apostrophes and commas, and even b

Answer 1

Found this question as a met almost the same task. And I've created function to print list in multi columns with the number of columns as parameter. Maybe not so elegant as one-liner solutions, but it could be useful for someone.

However, it handles incomplete lists, ex.: it can print list of 11 in 3 rows.

Function splitted for better readability:

def is_printable(my_list):
    return len(my_list) > 0

def create_empty_list(columns):
    result = []
    for num in range(0, columns):
        result.append([])
    return result

def fill_empty_list(empty_list, my_list, columns):
    column_depth = len(my_list) / columns if len(my_list) % columns == 0 else len(my_list) / columns + 1
    item_index = 0
    for column in range(0, columns):
        while len(empty_list[column]) < column_depth:
            if item_index < len(my_list):
                empty_list[column].append(my_list[item_index])
            else:
                empty_list[column].append(" ")  # last column could be incomplete, fill it with space
            item_index += 1

def print_list_in_columns(my_list, columns=1):
    if not is_printable(my_list):
        print 'Nothing to print, sorry...'
        return
    column_width = 25  #(in symbols) Also can be calculated automatically  
    list_to_print = create_empty_list(columns)
    fill_empty_list(list_to_print, my_list, columns)
    iterators = ["it" + str(i) for i in range(0, columns)]
    for iterators in zip(*list_to_print):
        print ("".join(str.ljust(i, column_width) for i in iterators))

and the call part:

foolist = ['exiv2-devel', 'mingw-libs', 'tcltk-demos', 'fcgi', 'netcdf', 
    'pdcurses-devel',     'msvcrt', 'gdal-grass', 'iconv', 'qgis-devel', 
    'qgis1.1', 'php_mapscript']

print_list_in_columns(foolist, 2)

Answer 2

Although not designed for it, the standard-library module cmd has a utility for printing a list of strings in multiple columns

import cmd
cli = cmd.Cmd()
cli.columnize(foolist, displaywidth=80)

You even then have the option of specifying the output location, with cmd.Cmd(stdout=my_stream)

Answer 3

See formatting-a-list-of-text-into-columns,

A general solution, handles any number of columns and odd lists. Tab characters separate columns, using generator expressions to save space.

def fmtcols(mylist, cols):
    lines = ("\t".join(mylist[i:i+cols]) for i in xrange(0,len(mylist),cols))
    return '\n'.join(lines)

Answer 4

It's useful to allow for uneven columns, without having to know in advance how many columns you can fit:

>>> words = [string.ascii_lowercase] + list(string.ascii_lowercase)
>>> print format_list(words)
abcdefghijklmnopqrstuvwxyz  b  d  f  h  j  l  n  p  r  t  v  x  z
a                           c  e  g  i  k  m  o  q  s  u  w  y

For your example:

>>> foolist = ['exiv2-devel', 'mingw-libs', 'tcltk-demos', 'fcgi',
... 'netcdf', 'pdcurses-devel', 'msvcrt', 'gdal-grass', 'iconv',
... 'qgis-devel', 'qgis1.1', 'php_mapscript']
>>> print format_list(foolist, spacing=4, width=31)
exiv2-devel       msvcrt
mingw-libs        gdal-grass
tcltk-demos       iconv
fcgi              qgis-devel
netcdf            qgis1.1
pdcurses-devel    php_mapscript

Here is the code. Note that it also handles words with ANSI color codes (such as from the colorama package) - they won't mess up the column widths.

ansi_pattern = re.compile(r'\x1b\[\d{1,2}m')


def get_nchars(string):
    """Return number of characters, omitting ANSI codes."""
    return len(ansi_pattern.sub('', string))


def format_list(items, indent=0, spacing=2, width=79):
    """Return string listing items along columns.

    items : sequence
        List of items to display that must be directly convertible into
        unicode strings. ANSI color codes may be present, and are taken
        into account in determining column widths
    indent : int
        Number of spaces in left margin.
    spacing : int
        Number of spaces between columns.
    width : int
        Maximum number of characters per line, including indentation.
    """
    if not items:
        return u''
    # Ensure all items are strings
    items = [unicode(item) for item in items]
    # Estimate number of columns based on shortest and longest items
    minlen = min(get_nchars(item) for item in items)
    maxlen = max(get_nchars(item) for item in items)
    # Assume one column with longest width, remaining with shortest.
    # Use negative numbers for ceiling division.
    ncols = 1 - (-(width - indent - maxlen) // (spacing + min(1, minlen)))
    ncols = max(1, min(len(items), ncols))

    # Reduce number of columns until items fit (or only one column)
    while ncols >= 1:
        # Determine number of rows by ceiling division
        nrows = -(-len(items) // ncols)
        # Readjust to avoid empty last column
        ncols = -(-len(items) // nrows)
        # Split items into columns, and test width
        columns = [items[i*nrows:(i+1)*nrows] for i in range(ncols)]
        totalwidth = indent - spacing + sum(
            spacing + max(get_nchars(item) for item in column)
            for column in columns
            )
        # Stop if columns fit. Otherwise, reduce number of columns and
        # try again.
        if totalwidth <= width:
            break
        else:
            ncols -= 1

    # Pad all items to column width
    for i, column in enumerate(columns):
        colwidth = max(get_nchars(item) for item in column)
        columns[i] = [
            item + ' ' * (colwidth - get_nchars(item))
            for item in column
            ]

    # Transpose into rows, and return joined rows
    rows = list(itertools.izip_longest(*columns, fillvalue=''))
    return '\n'.join(
        ' ' * indent + (u' ' * spacing).join(row).rstrip()
        for row in rows
        )

Answer 5

I needed to adjust each of the columns. I have implemented this code

def print_sorted_list(data, columns):
    if data:
        gap = 2
        ljusts = {}
        for count, item in enumerate(sorted(data), 1):
            column = count % columns
            ljusts[column] = len(item) if (column not in ljusts) else max(ljusts[column], len(item))

        for count, item in enumerate(sorted(data), 1):
            print item.ljust(ljusts[count % columns] + gap),
            if (count % columns == 0) or (count == len(data)):
                print

Example:

foolist = ['exiv2-devel', 'mingw-libs', 'tcltk-demos', 'fcgi', 'netcdf',
           'pdcurses-devel', 'msvcrt', 'gdal-grass', 'iconv', 'qgis-devel',
           'qgis1.1', 'php_mapscript', 'blablablablablablabla', 'fafafafafafa']
print_sorted_list(foolist, 4)

Output:

blablablablablablabla   exiv2-devel      fafafafafafa    fcgi        
gdal-grass              iconv            mingw-libs      msvcrt      
netcdf                  pdcurses-devel   php_mapscript   qgis-devel  
qgis1.1                 tcltk-demos   

Answer 6

For Python >=3.6, slight update to @JoshuaZastrow's answer using f-strings and adding clear method to adjust columns

cols = 5
[print(f'{key:20}', end='\t') if (idx + 1) % cols else print(f'{key}') for idx, key in enumerate(list_variable)]

or

cols = 5
for idx, key in enumerate(list_variable):
    if (idx + 1) % cols:
        print(f'{key:20}', end='\t')
    else:
        print(f'{key}')