how to format sublists in a tabular way automatically? - python-3.x

Question

I have the following list, which contains sublists
tableData = [['apples', 'oranges', 'cherries', 'banana'],['Alice', 'Bob', 'Carol', 'David'], ['dogs', 'cats', 'moose', 'goose']]
My aim is to format them that way
apples Alice dogs
oranges Bob cats
cherries Carol moose
banana David goose
The code below do that
In [55]: for nested_list in zip(*tableData):
print("{:>9} {:>9} {:>9}".format(*nested_list))
Yet what bugs me is I need to specify manually the format of each sublist.
I've been trying to find a way to do it automatically with a for loop but I did not find anything relevant on how to do it.
Any tips are more than welcomed.
Thanks.

Answer 1

How about this:
for line in zip(*tableData):
for word in line:
print("{:>9}".format(word), end=' ')
print()
Explanation
If the print() was absent, all the sublists would be put on a single line like this
apples Alice dogs oranges Bob cats cherries Carol moose banana David goose
The print() allows a newline

Answer 2

If you just want to use {:>9} as the format code with an arbitrary number of columns, try this:
fieldFormat = ' '.join(['{:>9}'] * len(tableData))
for nestedList in zip(*tableData):
print(fieldFormat.format(*nestedList))
This just creates a list of {:>9} format specifiers, one for each column in tableData, then joins them together with spaces.
If you want to automatically calculate the field widths as well, you can do this:
fieldWidths = [max(len(word) for word in col) for col in tableData]
fieldFormat = ' '.join('{{:>{}}}'.format(wid) for wid in fieldWidths)
for nestedList in zip(*tableData):
print(fieldFormat.format(*nestedList))
fieldWidths is generated from a list comprehension that calculates the maximum length of each word in each column. From the inside:
(len(word) for word in col)
This is a generator that will produce the length of each word in col.
max(len(word) for word in col)
Feeding the generator (or any iterable) into max will calculate the maximum value of everything produced by the iterable.
[max(len(word) for word in col) for col in tableData]
This list comprehension produces the maximum length of all words in each column col of data in tableData.
fieldFormat is then produded by transforming fieldWidths into format specifiers. Again from the inside:
'{{:>{}}}'.format(wid)
This formats wid into the {:>#} format. {{ is a way to have a format specifier produce a {; similarly, }} produces }. The {} in the middle is what actually gets formatted with wid.
('{{:>{}}}'.format(wid) for wid in fieldWidths)
This is a generator function that does the above formatting for each width listed in fieldWidths.
fieldFormat = ' '.join('{{:>{}}}'.format(wid) for wid in fieldWidths)
This just joins those formats together with spaces in between to create the fieldFormat format specifier.