Using rjust and reducing for loops in python

Question

I'm attempting to define a function that takes a list of arrangements of strings and shows it in an efficient table with every section right-justified. Accept that all the inward lists will contain similar number of strings. For instance, the value could resemble this:

tableData = [['apples', 'oranges', 'cherries', 'banana'],

['Alice', 'Bob', 'Carol', 'David'],

['dogs', 'cats', 'moose', 'goose']]

What your function will print:

    apples Alice   dogs

   oranges   Bob   cats

  cherries Carol  moose

    banana David  goose

With a help of a hint, I came till here,

def printable(tableData):

    newTable = np.zeros((len(tableData[0]),len(tableData)))

    colWidths = [0] * len(tableData)

    for i in range(0,len(tableData)):

        colWidths[i] = max(tableData[i], key=len)

    largest = max(colWidths, key=len)

    for i in range(0,len(tableData)):

        for j in range(0,len(tableData[0])):

            newTable[i][j] = tableData[j][i].rjust(len(largest))

I'm horrified at the no. of for loops. As an amateur, I'm actually escaping the 'for-loop' mode. Likewise, I'm considering on the best type of assault for this issue. Much appreciated.

Answer 1

Here's single direction to do this in plain Python. We can use zip to transpose the table so we can get the most extreme width of every column.

table_data = [

    ['apples', 'oranges', 'cherries', 'banana'],

    ['Alice', 'Bob', 'Carol', 'David'],

    ['dogs', 'cats', 'moose', 'goose'],

]

# Determine the width of each column

widths = [max(map(len, column)) for column in zip(*table_data)]

new_table = [[s.rjust(w) for s, w in zip(row, widths)]

    for row in table_data]

for row in new_table:

    print(row)

output:

['apples', 'oranges', 'cherries', 'banana']

[' Alice', '    Bob', '   Carol', ' David']

['  dogs', '   cats', '   moose', ' goose']

In the event that you don't actually require another 2D list, and you simply need to print the data, you can accomplish something like this:

for row in table_data:

    print(*(s.rjust(w) for s, w in zip(row, widths)))

output:

apples oranges cherries banana

 Alice     Bob    Carol  David

  dogs    cats    moose  goose

Look at this new version which will transpose the table

widths = [max(map(len, row)) for row in table_data]

new_table = [[s.rjust(w) for s, w in zip(row, widths)] for row in zip(*table_data)]

for row in new_table:

    print(row)

output:

['  apples', 'Alice', ' dogs']

[' oranges', '  Bob', ' cats']

['cherries', 'Carol', 'moose']

['  banana', 'David', 'goose']

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