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Python Linked List sep: Questions
How to print number with commas as thousands separators?
5 answers
I am trying to print an integer in Python 2.6.1 with commas as thousands separators. For example, I want to show the number 1234567 as 1,234,567. How would I go about doing this? I have seen many examples on Google, but I am looking for the simplest practical way.
It does not need to be locale-specific to decide between periods and commas. I would prefer something as simple as reasonably possible.
Answer #1
Locale unaware
"{:,}".format(value) # For Python ‚â•2.7
f"{value:,}" # For Python ‚â•3.6
Locale aware
import locale
locale.setlocale(locale.LC_ALL, "") # Use "" for auto, or force e.g. to "en_US.UTF-8"
"{:n}".format(value) # For Python ‚â•2.7
f"{value:n}" # For Python ‚â•3.6
Reference
Per Format Specification Mini-Language,
The
","option signals the use of a comma for a thousands separator. For a locale aware separator, use the"n"integer presentation type instead.
Answer #2
I got this to work:
>>> import locale
>>> locale.setlocale(locale.LC_ALL, "en_US")
"en_US"
>>> locale.format("%d", 1255000, grouping=True)
"1,255,000"
Sure, you don"t need internationalization support, but it"s clear, concise, and uses a built-in library.
P.S. That "%d" is the usual %-style formatter. You can have only one formatter, but it can be whatever you need in terms of field width and precision settings.
P.P.S. If you can"t get locale to work, I"d suggest a modified version of Mark"s answer:
def intWithCommas(x):
if type(x) not in [type(0), type(0L)]:
raise TypeError("Parameter must be an integer.")
if x < 0:
return "-" + intWithCommas(-x)
result = ""
while x >= 1000:
x, r = divmod(x, 1000)
result = ",%03d%s" % (r, result)
return "%d%s" % (x, result)
Recursion is useful for the negative case, but one recursion per comma seems a bit excessive to me.
Python Linked List sep: Questions
How would you make a comma-separated string from a list of strings?
5 answers
What would be your preferred way to concatenate strings from a sequence such that between every two consecutive pairs a comma is added. That is, how do you map, for instance, ["a", "b", "c"] to "a,b,c"? (The cases ["s"] and [] should be mapped to "s" and "", respectively.)
I usually end up using something like "".join(map(lambda x: x+",",l))[:-1], but also feeling somewhat unsatisfied.
Answer #1
my_list = ["a", "b", "c", "d"]
my_string = ",".join(my_list)
"a,b,c,d"
This won"t work if the list contains integers
And if the list contains non-string types (such as integers, floats, bools, None) then do:
my_string = ",".join(map(str, my_list))
