Re: howto remove the thousand separator
pyth0n3r pyth0...@gmail.com wrote:
I came across a problem that when i deal with int data with ',' as
thousand separator, such as 12,916, i can not change it into int() or
float(). How can i remove the comma in int data?
Any reply will be appreciated!!
Parse it using the locale module, just be sure to set the correct locale
first:
import locale
locale.setlocale(locale.LC_ALL, '')
'English_United Kingdom.1252'
locale.atoi('1,000')
1000
locale.atof('1,000')
1000.0
locale.setlocale(locale.LC_ALL, 'French_France')
'French_France.1252'
locale.atof('1,000')
1.0
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Re: Re: howto remove the thousand separator
Hi D'A,
Thanks alot for your reply, it works for me perfectly.
Best,
Chen
On Mon, 15 Apr 2013 02:57:35 +0800
pyth0n3r pyth0...@gmail.com wrote:
float(). How can i remove the comma in int data? Any reply will be
int(n.replace(',', ''))
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Re: howto remove the thousand separator
On Mon, 15 Apr 2013 03:19:43 +0100, Rotwang wrote: On 15/04/2013 02:14, Steven D'Aprano wrote: On Sun, 14 Apr 2013 17:44:28 -0700, Mark Janssen wrote: On Sun, Apr 14, 2013 at 5:29 PM, Steven D'Aprano steve+comp.lang.pyt...@pearwood.info wrote: On Sun, 14 Apr 2013 12:06:12 -0700, Mark Janssen wrote: cleaned='' for c in myStringNumber: if c != ',': cleaned+=c int(cleaned) due to being an O(N**2) algorithm. What on earth makes you think that is an O(n**2) algorithm and not O(n)? Strings are immutable. Consider building up a single string from four substrings: s = '' s += 'fe' s += 'fi' s += 'fo' s += 'fum' Python *might* optimize the first concatenation, '' + 'fe', to just reuse 'fe', (but it might not). Let's assume it does, so that no copying is needed. Then it gets to the second concatenation, and now it has to copy characters, because strings are immutable and cannot be modified in place. Actually, I believe that CPython is optimised to modify strings in place where possible, so that the above would surprisingly turn out to be O(n). See the following thread where I asked about this: I deliberately didn't open that can of worms, mostly because I was in a hurry, but also because it's not an optimization you can rely on. It depends on the version, implementation, operating system, and the exact code running. 1) It only applies to code running under some, but not all, versions of CPython. It does not apply to PyPy, Jython, IronPython, and probably not other implementations. 2) Even under CPython, it can fail. It *will* fail if you have multiple references to the same strings. And it *may* fail depending on the vagaries of the memory management system in place, e.g. code that is optimized on Linux may fail to optimize under Windows, leading to slow code. As far as I'm concerned, the best advice regarding this optimization is: - always program as if it doesn't exist; - but be glad it does when you're writing quick and dirty code in the interactive interpreter, where the convenience of string concatenation may be just too darn convenient to bother doing the right thing. http://groups.google.com/group/comp.lang.python/browse_thread/ thread/990a695fe2d85c52 (Sorry for linking to Google Groups. Does anyone know of a better c.l.p. web archive?) The canonical (although possibly not the best) archive for c.l.p. is the python-list mailing list archive: http://mail.python.org/mailman/listinfo/python-list -- Steven -- http://mail.python.org/mailman/listinfo/python-list
Re: howto remove the thousand separator
On Sun, 14 Apr 2013 22:35:42 -0400, Roy Smith wrote: In article kkfodv$f5m$1...@news.albasani.net, Walter Hurry walterhu...@lavabit.com wrote: On Mon, 15 Apr 2013 11:29:17 +1000, Chris Angelico wrote: There are actually a lot of optimizations done, so it might turn out to be O(n) in practice. But strictly in the Python code, yes, this is definitely O(n*n). In any event, Janssen should cease and desist offering advice here if he can't do better than that. That's a little harsh. Sure, it was a sub-optimal way to write the code (for all the reasons people mentioned), but it engendered a good discussion. Agreed. I'd rather people come out with poor code, and LEARN from the answers, than feel that they dare not reply until they're an expert. -- Steven -- http://mail.python.org/mailman/listinfo/python-list
Re: howto remove the thousand separator
On Mon, Apr 15, 2013 at 5:03 PM, Steven D'Aprano steve+comp.lang.pyt...@pearwood.info wrote: On Mon, 15 Apr 2013 03:19:43 +0100, Rotwang wrote: On 15/04/2013 02:14, Steven D'Aprano wrote: Strings are immutable. Consider building up a single string from four substrings: Actually, I believe that CPython is optimised to modify strings in place where possible, so that the above would surprisingly turn out to be O(n). See the following thread where I asked about this: I deliberately didn't open that can of worms, mostly because I was in a hurry, but also because it's not an optimization you can rely on. It depends on the version, implementation, operating system, and the exact code running. As far as I'm concerned, the best advice regarding this optimization is: - always program as if it doesn't exist; - but be glad it does when you're writing quick and dirty code in the interactive interpreter, where the convenience of string concatenation may be just too darn convenient to bother doing the right thing. Agreed; that's why, in my reply, I emphasized that the pure Python code IS quadratic, even though the actual implementation might turn out linear. (I love that word might. Covers myriad possibilities on both sides.) Same goes for all sorts of other possibilities. I wouldn't test string equality with 'is' without explicit interning, even if I'm testing a constant against another constant in the same module - but I might get a big performance boost if the system's interned all its constants for me. ChrisA -- http://mail.python.org/mailman/listinfo/python-list
Re: howto remove the thousand separator
On 15/04/2013 08:03, Steven D'Aprano wrote: On Mon, 15 Apr 2013 03:19:43 +0100, Rotwang wrote: [...] (Sorry for linking to Google Groups. Does anyone know of a better c.l.p. web archive?) The canonical (although possibly not the best) archive for c.l.p. is the python-list mailing list archive: http://mail.python.org/mailman/listinfo/python-list Thanks to both you and Ned. -- http://mail.python.org/mailman/listinfo/python-list
howto remove the thousand separator
Hi, I came across a problem that when i deal with int data with ',' as thousand separator, such as 12,916, i can not change it into int() or float(). How can i remove the comma in int data? Any reply will be appreciated!! Best, Chen -- http://mail.python.org/mailman/listinfo/python-list
Re: howto remove the thousand separator
On Sun, Apr 14, 2013 at 11:57 AM, pyth0n3r pyth0...@gmail.com wrote: I came across a problem that when i deal with int data with ',' as thousand separator, such as 12,916, i can not change it into int() or float(). How can i remove the comma in int data? Any reply will be appreciated!! cleaned='' for c in myStringNumber: if c != ',': cleaned+=c int(cleaned) mark -- http://mail.python.org/mailman/listinfo/python-list
Re: howto remove the thousand separator
On 04/14/2013 02:57 PM, pyth0n3r wrote:
Hi,
I came across a problem that when i deal with int data with ',' as
thousand separator, such as 12,916, i can not change it into int() or
float().
How can i remove the comma in int data?
Any reply will be appreciated!!
Best,
Chen
I would do int(num.replace(',', ''))
-m
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Re: howto remove the thousand separator
On Mon, 15 Apr 2013 02:57:35 +0800
pyth0n3r pyth0...@gmail.com wrote:
float(). How can i remove the comma in int data? Any reply will be
int(n.replace(',', ''))
--
D'Arcy J.M. Cain da...@druid.net | Democracy is three wolves
http://www.druid.net/darcy/| and a sheep voting on
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Re: howto remove the thousand separator
I would do int(num.replace(',', ''))
That's much more pythonic than my C-ish version
Mark
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Re: howto remove the thousand separator
On 14/04/2013 19:57, pyth0n3r wrote:
Hi,
I came across a problem that when i deal with int data with ',' as
thousand separator, such as 12,916, i can not change it into int() or
float().
How can i remove the comma in int data?
Any reply will be appreciated!!
Best,
Chen
Use the string replace method thus.
'12,916'.replace(',', '')
'12916'
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Re: howto remove the thousand separator
On Sun, 14 Apr 2013 12:06:12 -0700, Mark Janssen wrote: cleaned='' for c in myStringNumber: if c != ',': cleaned+=c int(cleaned) Please don't write code like that. Firstly, it's long and bloated, and runs at the speed of Python, not C. Second, it runs at the speed of SOO Python, not fast Python, due to being an O(N**2) algorithm. If you don't know what O(N**2) means, you should read this for an introduction: http://www.joelonsoftware.com/articles/fog000319.html -- Steven -- http://mail.python.org/mailman/listinfo/python-list
Re: howto remove the thousand separator
On Sun, Apr 14, 2013 at 5:29 PM, Steven D'Aprano steve+comp.lang.pyt...@pearwood.info wrote: On Sun, 14 Apr 2013 12:06:12 -0700, Mark Janssen wrote: cleaned='' for c in myStringNumber: if c != ',': cleaned+=c int(cleaned) due to being an O(N**2) algorithm. What on earth makes you think that is an O(n**2) algorithm and not O(n)? Mark -- http://mail.python.org/mailman/listinfo/python-list
Re: howto remove the thousand separator
On Sun, 14 Apr 2013 17:44:28 -0700, Mark Janssen wrote: On Sun, Apr 14, 2013 at 5:29 PM, Steven D'Aprano steve+comp.lang.pyt...@pearwood.info wrote: On Sun, 14 Apr 2013 12:06:12 -0700, Mark Janssen wrote: cleaned='' for c in myStringNumber: if c != ',': cleaned+=c int(cleaned) due to being an O(N**2) algorithm. What on earth makes you think that is an O(n**2) algorithm and not O(n)? Strings are immutable. Consider building up a single string from four substrings: s = '' s += 'fe' s += 'fi' s += 'fo' s += 'fum' Python *might* optimize the first concatenation, '' + 'fe', to just reuse 'fe', (but it might not). Let's assume it does, so that no copying is needed. Then it gets to the second concatenation, and now it has to copy characters, because strings are immutable and cannot be modified in place. Showing the *running* total of characters copied: 'fe' + 'fi' = 'fefi' # four characters copied 'fefi' + 'fo' = 'fefifo' # 4 + 6 = ten characters copied 'fefifo' + 'fum' = 'fefifofum' # 10 + 9 = nineteen characters copied Notice how each intermediate substring gets copied repeatedly? In order to build up a string of length 9, we've had to copy at least 19 characters. With only four substrings, it's not terribly obvious how badly this performs. So let's add some more substrings, and see how the running total increases: 'fefifofum' + 'foo' = 'fefifofumfoo' # 19 + 12 = 31 'fefifofumfoo' + 'bar' = 'fefifofumfoobar' # 31 + 15 = 46 'fefifofumfoobar' + 'baz' = 'fefifofumfoobarbaz' # 46 + 18 = 64 'fefifofumfoobarbaz' + 'spam' = 'fefifofumfoobarbazspam' # 64 + 22 = 86 To build up a string of length 22, we've had to copy, and re-copy, and re- re-copy, 86 characters in total. And the string gets bigger, the inefficiency gets worse. Each substring (except the very last one) gets copied multiple times; the number of times it gets copied is proportional to the number of substrings. If the substrings are individual characters, then each character is copied a number of times proportional to the number of characters N; since there are N characters, each being copied (proportional to) N times, that makes N*N or N**2. -- Steven -- http://mail.python.org/mailman/listinfo/python-list
Re: howto remove the thousand separator
On Mon, Apr 15, 2013 at 11:14 AM, Steven D'Aprano steve+comp.lang.pyt...@pearwood.info wrote: On Sun, 14 Apr 2013 17:44:28 -0700, Mark Janssen wrote: What on earth makes you think that is an O(n**2) algorithm and not O(n)? Python *might* optimize the first concatenation, '' + 'fe', to just reuse 'fe', (but it might not). Let's assume it does, so that no copying is needed. Then it gets to the second concatenation, and now it has to copy characters, because strings are immutable and cannot be modified in place. There are actually a lot of optimizations done, so it might turn out to be O(n) in practice. But strictly in the Python code, yes, this is definitely O(n*n). ChrisA -- http://mail.python.org/mailman/listinfo/python-list
Re: howto remove the thousand separator
On 15/04/2013 02:14, Steven D'Aprano wrote: On Sun, 14 Apr 2013 17:44:28 -0700, Mark Janssen wrote: On Sun, Apr 14, 2013 at 5:29 PM, Steven D'Aprano steve+comp.lang.pyt...@pearwood.info wrote: On Sun, 14 Apr 2013 12:06:12 -0700, Mark Janssen wrote: cleaned='' for c in myStringNumber: if c != ',': cleaned+=c int(cleaned) due to being an O(N**2) algorithm. What on earth makes you think that is an O(n**2) algorithm and not O(n)? Strings are immutable. Consider building up a single string from four substrings: s = '' s += 'fe' s += 'fi' s += 'fo' s += 'fum' Python *might* optimize the first concatenation, '' + 'fe', to just reuse 'fe', (but it might not). Let's assume it does, so that no copying is needed. Then it gets to the second concatenation, and now it has to copy characters, because strings are immutable and cannot be modified in place. Actually, I believe that CPython is optimised to modify strings in place where possible, so that the above would surprisingly turn out to be O(n). See the following thread where I asked about this: http://groups.google.com/group/comp.lang.python/browse_thread/thread/990a695fe2d85c52 (Sorry for linking to Google Groups. Does anyone know of a better c.l.p. web archive?) -- http://mail.python.org/mailman/listinfo/python-list
Re: howto remove the thousand separator
On Mon, 15 Apr 2013 11:29:17 +1000, Chris Angelico wrote: There are actually a lot of optimizations done, so it might turn out to be O(n) in practice. But strictly in the Python code, yes, this is definitely O(n*n). In any event, Janssen should cease and desist offering advice here if he can't do better than that. -- http://mail.python.org/mailman/listinfo/python-list
Re: howto remove the thousand separator
In article kkfodv$f5m$1...@news.albasani.net, Walter Hurry walterhu...@lavabit.com wrote: On Mon, 15 Apr 2013 11:29:17 +1000, Chris Angelico wrote: There are actually a lot of optimizations done, so it might turn out to be O(n) in practice. But strictly in the Python code, yes, this is definitely O(n*n). In any event, Janssen should cease and desist offering advice here if he can't do better than that. That's a little harsh. Sure, it was a sub-optimal way to write the code (for all the reasons people mentioned), but it engendered a good discussion. -- http://mail.python.org/mailman/listinfo/python-list
Re: howto remove the thousand separator
In article kkfnun$kpj$1...@dont-email.me, Rotwang sg...@hotmail.co.uk wrote: (Sorry for linking to Google Groups. Does anyone know of a better c.l.p. web archive?) http://dir.gmane.org/gmane.comp.python.general -- Ned Deily, n...@acm.org -- http://mail.python.org/mailman/listinfo/python-list
