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

User · Answer

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

User · Answer

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

User · Answer

mylist    0 30000000000000004  0 5  0 20000000000000001  myRoundedList     round x 2  for x in mylist      0 3  0 5  0 2

User · Answer

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

User · Answer

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

User · Answer

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    gt  gt  gt  from decimal import    gt  gt  gt  mylist    0 30000000000000004  0 5  0 20000000000000001   gt  gt  gt  getcontext   prec   2  gt  gt  gt      2f    e for e in mylist    0 30    0 50    0 20    gt  gt  gt   Decimal    2f    e  for e in mylist   Decimal  0 30    Decimal  0 50    Decimal  0 20     gt  gt  gt  data    float Decimal    2f    e   for e in mylist   gt  gt  gt  data  0 3  0 5  0 2

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

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