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:
You might want to look at Python's decimal module, which can make using floating point numbers and doing arithmetic with them a lot more intuitive. Here's a trivial example of one way of using it to "clean up" your list values:
>>> from decimal import *
>>> mylist = [0.30000000000000004, 0.5, 0.20000000000000001]
>>> getcontext().prec = 2
>>> ["%.2f" % e for e in mylist]
['0.30', '0.50', '0.20']
>>> [Decimal("%.2f" % e) for e in mylist]
[Decimal('0.30'), Decimal('0.50'), Decimal('0.20')]
>>> data = [float(Decimal("%.2f" % e)) for e in mylist]
>>> data
[0.3, 0.5, 0.2]
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))
"%.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]
You can use the built-in map along with a lambda expression:
my_list = [0.2111111111, 0.5, 0.3777777777]
my_list_rounded = list(map(lambda x: round(x, ndigits=2), my_list))
my_list_rounded
Out[3]: [0.21, 0.5, 0.38]
Alternatively you could also create a named function for the rounding up to a specific digit using partial from the functools module for working with higher order functions:
from functools import partial
my_list = [0.2111111111, 0.5, 0.3777777777]
round_2digits = partial(round, ndigits=2)
my_list_rounded = list(map(round_2digits, my_list))
my_list_rounded
Out[6]: [0.21, 0.5, 0.38]
mylist = [0.30000000000000004, 0.5, 0.20000000000000001]
myRoundedList = [round(x,2) for x in mylist]
# [0.3, 0.5, 0.2]
Another option which doesn't require numpy is:
precision = 2
myRoundedList = [int(elem*(10**precision)+delta)/(10.0**precision) for elem in myList]
# delta=0 for floor
# delta = 0.5 for round
# delta = 1 for ceil