Pretty print table from 2d list with tabs

Question

I've tried to use pandas and PrettyTable but neither of them helped me in my case.

Here is my case:

left_headers = ['Numbers', 'Animals', 'Names', 'Flowers']
data = [
    [1, 2, 3, 4, 5, 6],
    ['dog', 'cat', 'rabbit', 'elephant', 'hyena', 'kangaroo'],
    ['short name', 'a very long name', '123', 'some text', 'different name', 'another name'],
    ['tulip', 'cactus', 'daffodil', 'hydrangea', 'geranium', 'rose']
]

Now I want it in this form:

Numbers 1           2                   3           4           5               6
Animals dog         cat                 rabbit      elephant    hyena           kangaroo
Names   short name  a very long name    123         some text   different name  another name
Flowers tulip       cactus              daffodil    hydrangea   geranium        rose

Data is separated by tabs not spaces. All beginning characters should be adjusted.

The main idea: headers are on left side. All data (and headers) are separated by some number of tabs. My problem is that I don't know how to predict how many tabs do I need to fit the data. I want to use as less tabs as possible to fit all data with minimal space but It should be at least one 'space' (like between "Numbers" and "1").

Edit: I did it with very ugly code. I added my answer.

Answer 1

The answer depends on the required output format

1. With one tab (\t) separation

With tab (\t) separation it is very easy to print it:

for header, items in zip(left_headers, data):
    print(header, '\t', '\t'.join(map(str, items)))

Output:

Numbers          1      2       3       4       5       6
animals          dog    cat     rabbit  elephant        hyena   kangaroo
name     short name     a very long name        123     some text       different name  another name
flowers          tulip  cactus  daffodil        hydrangea       geranium        rose

Short explanation

• map(str, items) turns a list of items into list of strings (one list was integers, so this is needed)
• '\t'.join(lst) creates a new string from items in a list lst, and joins them with \t.
• zip(lst1, lst2) is used to iterate two lists taking one element at time from each one.

2. With space separation (equal width columns)

This is one-liner with tabulate

from tabulate import tabulate
print(tabulate(data, showindex=left_headers, tablefmt='plain'))

Output

Numbers  1           2                 3         4          5               6
animals  dog         cat               rabbit    elephant   hyena           kangaroo
name     short name  a very long name  123       some text  different name  another name
flowers  tulip       cactus            daffodil  hydrangea  geranium        rose

3. With variable tab separation

This is the toughest one. One thing you have to do is to assume that how the tabulator is handled by the program that uses the output. Here it is assumed that "tab = 4 spaces".

import math 
import os 

SPACES_PER_TAB = 4

table = [[str(item) for item in items] for items in data]
for header, items in zip(left_headers, table):
    items.insert(0, header)

offset_table = [] # in tabs
for col in zip(*table):
    lengths = [len(x) for x in col]
    cell_length = math.ceil(max(lengths)/SPACES_PER_TAB)*SPACES_PER_TAB
    offsets_s = [cell_length - length for length in lengths] # in spaces
    additional_tabs = 1 if min(offsets_s) == 0 else 0
    offsets = [math.ceil(o/SPACES_PER_TAB) + additional_tabs for o in offsets_s]
    offset_table.append(offsets)


with open('table_out.txt', 'w') as f:
    for row, row_offsets in zip(table, zip(*offset_table)):
        for item, offset in zip(row, row_offsets):
            f.write(item)
            f.write('\t'*offset)
        f.write('\n')

The output looks like this (tabs copied here won't look good, so here's a printscreen from Notepad++)

Short explanation

• First, we just create one table called table that contains the headers and the data as strings.
• Then, we calculate the lengths of the cells (in spaces), assuming there is one additional space between cells. Then, one additional space is added if some cell would end up having no space before next cell.
• Here the builtin zip() is really put to work, and it is used for example to transpose lists of lists by zip(*lst).
• Finally, the results are written into an output file.

Answer 2

You can use pandas to achieve this:

import pandas as pd

left_headers = ['Numbers', 'animals', 'name', 'flowers']
data = [
    [1, 2, 3, 4, 5, 6],
    ['dog', 'cat', 'rabbit', 'elephant', 'hyena', 'kangaroo'],
    ['short name', 'a very long name', '123', 'some text', 'different name', 'another name'],
    ['tulip', 'cactus', 'daffodil', 'hydrangea', 'geranium', 'rose']
]

df = pd.DataFrame(data, index=left_headers)
print(df.to_string(header=False))

The output is:

Numbers           1                 2         3          4               5             6
animals         dog               cat    rabbit   elephant           hyena      kangaroo
name     short name  a very long name       123  some text  different name  another name
flowers       tulip            cactus  daffodil  hydrangea        geranium          rose

Answer 3

I did it! My code is not simple but does what I want:

left_headers = ['Numbers', 'Animals', 'Names', 'Flowers']
data = [
    [1, 2, 3, 4, 5, 6],
    ['dog', 'cat', 'rabbit', 'elephant', 'hyena', 'kangaroo'],
    ['short name', 'a very long name', '123', 'some text', 'different name', 'another name'],
    ['tulip', 'cactus', 'daffodil', 'hydrangea', 'geranium', 'rose']
]
for i in range(len(left_headers)):
    print(left_headers[i], end="\t")
    how_many_tabs_do_i_need = max([len(h) for h in left_headers]) // 4
    how_many_tabs_actual_word_has = len(left_headers[i]) // 4
    print("\t"*(how_many_tabs_do_i_need-how_many_tabs_actual_word_has), end="")
    for j in range(len(data[0])):
        how_many_tabs_do_i_need = max([len(str(data[k][j])) for k in range(len(left_headers))]) // 4
        how_many_tabs_actual_word_has = len(str(data[i][j])) // 4
        print(str(data[i][j]) +"\t"*(how_many_tabs_do_i_need - how_many_tabs_actual_word_has + 1), end="")
    print()

The output:

Numbers 1           2                   3           4           5               6               
Animals dog         cat                 rabbit      elephant    hyena           kangaroo        
Names   short name  a very long name    123         some text   different name  another name    
Flowers tulip       cactus              daffodil    hydrangea   geranium        rose

If one's can simplify the code - the problem is open.