如何在Python中设置常规选项以在各处仅显示N位数字？

Question

I want to work with 3 digits after the decimal point in Python. What is the relevant setting to modify ?

I want that 1.0 / 3 would return 0.333, and not 0.3333333333333333 like it is the case in my Jupyter Notebook, using python 2.7.11 and Anaconda 4.0.0.

In my research, I heard about the Decimal class, but I don't want to use Decimal(x) in my code every time I display a float, neither the string formating or the round function, though I use it for the time being (because I don't want to use it every time).

I think there is a general solution, a setting computed only once.

Answer 1

use numpy and try this;

round(1.0/3, 3)

or

>>> 1.0/3
0.3333333333333333

>>> '{:0.3f}'.format(1.0/3)
'0.333'

Answer 2

There is no "one-time" solution to your problem. And I think that your approach might be a little misguided.

I suppose that your interaction with Jupyter or Ipython has lead you to the conclusion that python is quite handy as a numerical calculator. Unfortunately both of the aforementioned programs are just wrappers or REPL programs and in the background come with the full programming language flexibility that Python offers.