Printing a Python dictionary in two rows with aligned columns

Question

I want to print a Python dictionary with keys in one row and values in another row.

Example:

d = {'a':'long val', 'b':None, 'long key':3, 'd':4}

I want to print it as

    a    | b | long key | d
long val |   |    3     | 4

How can I do this?

Answer 1

I'd say that either you iterate twice or you build the two output lines first and then display them:

d = {'a': 'long val', 'b': None, 'long key': 3, 'd': 4}
headers = ""
row = ""
for k, v in d.items():
    if row != "":
        row += " | "
        headers += " | "
    max_len = max(len(str(k)), len(str(v)) if v else 1)
    headers += str(k).center(max_len)
    row += str(v).center(max_len) if v else " "
print(headers)
print(row)

But it looks like a lot of hassle to avoid a double iteration over a simple dict.