Question

Is there any way to pass an “empty” numeric type into a numeric format specifier and have it print the blank space associated with that specifier?

ie.

n = "Scientific:"
v = 123.321
strfmt = "%5.4E"
output = "%s|"+strfmt+"|"
print output % (n, v)

>   Scientific:|1.2332E+02|

v = EMPTY
print output % (n, v)

>   Scientific:|          |

The ultimate goal is to deal with incomplete lines without adaptively changing the format string while looping

perline = 3
n = ["1st:","2nd:","3rd:","4th:","5th:","6th:"]
v = [1.0, 2.0, 3.0, 4.0]

strfmt = "%5.4E"
output = ("%s|"+strfmt+"|  ")*perline+"\n"

for args in map(EMPTY,*[iter(n),iter(v)]*perline):
    print output % args

>   1st:|1.0000E+00|  2nd:|2.0000E+00|  3rd:|3.0000E+00|
>   4th:|4.0000E+00|  5th:|          |  6th:|          |

To execute the above code I replaced EMPTY with None although that gives an error when you pass None to the format string

Answer 1

After viewing the responses it appears that there is no thing you can pass to a numeric format specifier to have it print the blank space associated with it.

There are a number of ways to work around this shown below. Personally I liked parts of Unutbu’s answer. I think the way I will ultimately do it is create two format specifiers at the beginning and use logic as suggested by Blender.