PEP 515: Underscores in Numeric Literals
PEP 515 adds the ability to use underscores in numeric literals for improved readability. For example:
>>> 1_000_000_000_000_000
1000000000000000
>>> 0x_FF_FF_FF_FF
4294967295
Single underscores are allowed between digits and after any base specifier. Leading, trailing, or multiple underscores in a row are not allowed.
The string formatting language also now has support for the '_' option to signal the use of an underscore for a thousands separator for floating point presentation types and for integer presentation type 'd'. For integer presentation types 'b', 'o', 'x', and 'X', underscores will be inserted every 4 digits:
>>> '{:_}'.format(1000000)
'1_000_000'
>>> '{:_x}'.format(0xFFFFFFFF)
'ffff_ffff'
See also:
PEP 515 – Underscores in Numeric Literals
PEP written by Georg Brandl and Serhiy Storchaka.
Exercise
Given a Numpy matrix a containing only integers, return a string representation of the element at the i-th row and j-th column. The string must use underscores as presented before (eg. 123456 must be converted into '123_456').