formatting - Set global output precision python

Question

I've written a library of functions to make my engineering homework easier, and use them in the python interpreter (kinda like a calculator). Some return matrices, some return floats.

The problem is, they return too many decimals. For example, currently, when a number is 0, I get an extremely small number as a return (e.g. 6.123233995736766e-17)

I know how to format outputs individually, but that would require adding a formatter for every line I type in the interpreter. I'm using python 2.6.

Is there a way to set the global output formatting (precision, etc...) for the session?

*Note: For scipy functions, I know I can use

scipy.set_printoptions(precision = 4, suppress = True)

but this doesn't seem to work for functions that don't use scipy.

Answer 1

One idea would be to add from __future__ import print_function (at the very top) and then override the standard print function. Here's a very simple implementation that prints floats with exactly two digits after the decimal point:

def print(*args):
    __builtins__.print(*("%.2f" % a if isinstance(a, float) else a
                         for a in args))

You would need to update your output code to use the print function, but at least it will be generic, rather than requiring custom formatting rules in each place. If you want to change how the formatting works, you just need to change the custom print function.