How to round each item in a list of floats to 2 decimal places?

Question

I have a list which consists of float values but they're too detailed to proceed. I know we can shorten them by using the ("%.f" % variable) operator, like:

result = [359.70000000000005] result = "%.2f" % result result = [359.70] 

My question is how can I turn a list of values into their rounded equivalents without using an iterator. I've tried something, but it throws a TypeError:

list = [0.30000000000000004, 0.5, 0.20000000000000001] list = "%.2f" % list TypeError: not all arguments converted during string formatting 

How can I provide a clean list like:

list = [0.30, 0.5, 0.20] 

Answer 1

"%.2f" does not return a clean float. It returns a string representing this float with two decimals.

my_list = [0.30000000000000004, 0.5, 0.20000000000000001] my_formatted_list = [ '%.2f' % elem for elem in my_list ] 

returns:

['0.30', '0.50', '0.20'] 

Also, don't call your variable list. This is a reserved word for list creation. Use some other name, for example my_list.

If you want to obtain [0.30, 0.5, 0.20] (or at least the floats that are the closest possible), you can try this:

my_rounded_list = [ round(elem, 2) for elem in my_list ] 

returns:

[0.29999999999999999, 0.5, 0.20000000000000001] 

Answer 2

If you really want an iterator-free solution, you can use numpy and its array round function.

import numpy as np myList = list(np.around(np.array(myList),2))