In Python, is there a max length float to string formatting parameter?

I have a program that prints matrices in the console which means I want the spacing for each matrix entry to be the same, regardless of how big the number is, positive or negative. I want numbers that do not need to be displayed as exponentials to not be displayed as such and floats with no non-zero decimals to be displayed without decimals. I am formatting any float number with the formatting rule:

"{: 8.3g}".format(number)

This formatting rule displays all numbers to take up exactly 8 characters, along with my preferences related to decimals and eponentials.

However, the exception to this is that very small numbers are displayed to take up 9 characters. For example:

("{: 8.3g}").format(-0.000000000000000000111) returns -1.11e-19.

I suspect it doesn't count the minus in front of the exponent but could be wrong. Any idea how to change the formatting rule to meet my requirements?

The width parameter is the minimal width, but if your exponent has two digits, you need a width of 9 to display the number with three significant digits as specified.

-x.xxe-xx
123456789

If you want the numbers aligned, give a width parameter that can host all your cases:

def f(x):
    result = f"{x: 8.3g}"
    print(f"{len(result)}: '{result}'")

def g(x):
    result = f"{x: 9.3g}"
    print(f"{len(result)}: '{result}'")

def h(x):
    result = f"{x: 10.3g}"
    print(f"{len(result)}: '{result}'")

f(1)
f(-1.11e-5)
f(1.11e-10)
f(-1.11e-100)
print()
g(1)
g(-1.11e-5)
g(1.11e-10)
g(-1.11e-100)
print()
h(1)
h(-1.11e-5)
h(1.11e-10)
h(-1.11e-100)

Output:

8: '       1'
9: '-1.11e-05'
9: ' 1.11e-10'
10: '-1.11e-100'

9: '        1'
9: '-1.11e-05'
9: ' 1.11e-10'
10: '-1.11e-100'

10: '         1'
10: ' -1.11e-05'
10: '  1.11e-10'
10: '-1.11e-100'

The sign is not to blame here. You already took care of that by using the space in the format string.