How to fill string with n character to make it a certain length in Python

user_11326083 0
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I'm having a tough time finding the exact wording for my question since I'm new to formatting strings.

Let's say I have two variables:

customer = 'John Doe'
balance = 39.99

I want to print a line that 25 characters wide, and fills the space between the two values with a specific character (in this case, periods):

'John Doe .......... 39.99'

So as I loop through customers, I want to print a line that is always 25 characters, with their name at the left, and their balance at the right, and allow the periods to adjust to fill the space between.

I can break this into multiple steps and accomplish the result... 

customer = 'Barry Allen'
balance = 99
spaces = 23 - len(customer + str(balance))
'{} {} {}'.format(customer, '.' * spaces, balance)

# of course, this assumes that len(customer + str(balance)) is less than 23 (which is easy to work around)

...but I'm curious if there is a more "elegant" way of doing it, such as with string formatting.

Is this even possible?

Thanks!

string-formatting formatting python-3.x python
2 Answers

You can use ljust() and rjust() of string objects in python: 

customer = 'John Doe'
balance = 39.99

output = customer.ljust(15, '.') + str(balance).rjust(10, '.')

print(output)
#John Doe............39.99

Depending on format you need, you can tune it with changing the widths or adding space characters.

user_32796030

If you did not want to have spaces on either side of the dots as the other answer would suggests, you can achieve that specifying formatting just as well:

"{:.<17s}{:.>8.2f}".format(customer, balance)

Would do 17 characters wide left aligned, . right padded string and 8 characters of right aligned, . left padded, float with precision of 2 decimal points.

You can do that same with an f-string (Python >=3.6):

f"{customer:.<17s}{balance:.>8.2f}"

However, if you also want to include the space on either side of the dots, it gets trickier. You can still do that, but you need to double pad / format or concatenate before filling in the gap:

"{:.<16s}{:.>9s}".format(f"{customer} ", f" {balance:>.2f}")

But I would be somewhat at pain to call that more elegant.

You could also do all that with formatting:

# Fill in with calculated number of "."
"{} {} {:.2f}".format(customer,
                      "."*(25 - (2 + len(customer) + len(f"{balance:.2f}"))),
                      balance)
# Similarly used for calculated width to pad with "."
"{} {:.^{}s} {:.2f}".format(customer,
                            "",
                            25 - (2 + len(customer) + len(f"{balance:.2f}")),
                            balance)

But again, more elegant is it really not.

user_92882000
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