Format output from list of lists into columns

Question

I'm working with a database and I'm trying to list all the tables in that one database. I can print them fine, but I'm having trouble formatting the tables correctly. I used pandas to format it and that works, but I'm trying to create this without pandas. This is how it is printing out so far:

TerritoryID TerritoryDescription RegionID
1581 Westboro 1
1730 Bedford 1
1833 Georgetown 1
2116 Boston 1
2139 Cambridge 1

I'm trying to get it to look something like this:

   TerritoryID TerritoryDescription RegionID
1. 1581        Westboro             1
2. 1730        Bedford              1
3. 1833        Georgetown           1
4. 2116        Boston               1
5. 2139        Cambridge            1

What I've tried is finding the maximum length of the lists and formatting them that way, since there are other tables I'm trying to format. This is what I tried doing, but, I get an error that says: object of type 'int' has no len()

def categories(menu, choice, cursor, connection):
    sql = "SELECT * FROM " + menu[choice - 1]
    cursor.execute(sql)
    rows = cursor.fetchall()
    lst = [list(elem) for elem in rows]
    connection.close()
    return lst


def columns(lst, cursor):
    header = []
    for field in cursor.description:
        header.append(field[0])
    print(' '.join(header))
    length_list = [len(element) for row in lst for element in row]
    column_width = max(length_list)
    for row in lst:
        row = "".join(element.ljust(column_width + 2) for element in row)
        print(row)

How would I fix this error? Or is there another way to do this?

Rusty Widebottom · Accepted Answer · 2020-04-12 23:14:07Z

2

Not every element in the row is a string. You can't take the len() of an int. Therefore, ensure everything is a string before taking its length.

Try making this change:

BEFORE

length_list = [len(element) for row in lst for element in row]

AFTER

length_list = [len(str(element)) for row in lst for element in row]

and also change this line too (wrap element in str():

BEFORE

row = "".join(element.ljust(column_width + 2) for element in row)

AFTER

row = "".join(str(element).ljust(column_width + 2) for element in row)

edited Apr 12, 2020 at 23:14

answered Apr 12, 2020 at 21:00

Rusty Widebottom

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2 Comments

Will91099 Over a year ago

So that got rid of the first error. But now it brings up Error: 'int' object has no attribute 'ljust' even though it was turned into a string?

Rusty Widebottom Over a year ago

Oh yeah, you have to wrap element in str() in the join statement too. I updated my answer - see above.

Alex · Accepted Answer · 2020-04-12 20:57:12Z

1

You can print lists of list as tables using python format strings:

# Input is expected as a list of list
rows = [
    ["TerritoryID", "TerritoryDescription", "RegionID"],
    ["1581", "Westboro", "1"], 
    ["1730","Bedford","1"], 
    ["1833","Georgetown","1"], 
    ["2116","Boston","1"], 
    ["2139","Cambridge","1"],
]

# First we get the max width of each column, like so:
max_col = list(max(map(len, x)) + 2 for x in list(map(list, zip(*rows))))

# Set some padding for the index column:
idx_pad = len(str(len(rows))) + 2

# Create a format string that will accept both values, and paddings:
s = "{:<{}}" + "{:<{}}" * len(max_col)

# Iterate the list of lists, printing each row:
for i, row in enumerate(rows):
    if i == 0:
        i = ""
    c = row + max_col
    c[::2] = row
    c[1::2] = max_col
    print(s.format(i, idx_pad, *c))
    idx_pad = old_idx

Which will print out:

   TerritoryID  TerritoryDescription  RegionID  
1  1581         Westboro              1         
2  1730         Bedford               1         
3  1833         Georgetown            1         
4  2116         Boston                1         
5  2139         Cambridge             1

answered Apr 12, 2020 at 20:57

Alex

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1 Comment

Will91099 Over a year ago

I'm still getting the object of type 'int' has no len() error, I'm guessing that's because the rows arent all strings. Would I have to convert the rows to strings and then that would fix it? @Alex

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