Discussion List Archives

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: CIF-JSON new draft

Bob,parsing a single number in loop is not a good proxy for working withlong array. I suppose if you try JSON file with, say, 1M numbersyou'll get results similar to what I got.M
On 1 May 2017 at 18:29, Robert Hanson <hansonr@stolaf.edu> wrote:> Do you consider that significant or not?>> JavaScript:>>  x = json.example["_flight.vector"][0]>  c = 0;> t = +new Date;> for (var i = 0; i < 10000000; i++) {>   c+= parseFloat(x);> }> t = +new Date - t;> document.write(t + " ms");>> 643 ms>> That was 10,000,000 conversions. To me, that's acceptable. JavaScript is> highly optimized. I'm sure the string->number conversion is one of its most> optimized features.>> Again, if you want actual "numbers" in the JSON, then you are asking,> probably, for:>> server/source: number -> string> web page: string -> number>> whether that string -> number is done by the page code writer using> parseFloat() or by the JSON interpreter using JSON.parse(), it is almost> certainly using the same native code. Actually, the JSON.parse() is more> time consuming, because it has to figure out what sort of value we have; as> CIF developers, we would know we have a float:>> x = json.example["_flight.vector"][0]>> t = +new Date;> var c = 0> for (var i = 0; i < 10000000; i++) {>   c += parseFloat(x);> }> t = +new Date - t;> document.write(t + " ms parseFloat()");> document.write("<br>")> t = +new Date;> var c = 0> for (var i = 0; i < 10000000; i++) {>   c += JSON.parse(x);> }> t = +new Date - t;> document.write(t + " ms JSON.parse()");>>> 659 ms parseFloat()> 1999 ms JSON.parse()>> So in JavaScript it is 3x faster to do it yourself rather than rely on the> generic JSON parser.>> Bob>>>>>> On Mon, May 1, 2017 at 12:03 PM, Marcin Wojdyr <wojdyr@gmail.com> wrote:>>>> >>> > Since we are targeting this as a low overhead representation, which I>> > associate with performance considerations, I am prepared to entertain>> > arguments about performance impact.  I am not, however, prepared to accept>> > unsupported assertions about performance.>>>> Fair enough, here is a microbenchmark for you. First using Python2.7:>>>> $ python -m timeit -s 'import json,sys' 'f=open("numbers.json"); numbers =>> json.load(f)["numbers"]'>> 100 loops, best of 3: 10.2 msec per loop>> $ python -m timeit -s 'import json,sys' 'f=open("strings.json"); numbers =>> [float(x) for x in json.load(f)["strings"]]'>> 10 loops, best of 3: 58.1 msec per loop>>>> In this case using strings is 5x slower.>>>> Now with Python 3.5:>>>> $ python3 -m timeit -s 'import json,sys' 'f=open("numbers.json"); numbers>> = json.load(f)["numbers"]'>> 100 loops, best of 3: 12.7 msec per loop>> $ python3 -m timeit -s 'import json,sys' 'f=open("strings.json"); numbers>> = [float(x) for x in json.load(f)["strings"]]'>> 10 loops, best of 3: 27.4 msec per loop>>>> The difference is smaller, but still >2x.>>>> The input files were prepared using this script:>>>> import json>> import random>> numbers = [round(random.uniform(-30, 30), 3) for _ in range(100000)]>> with open('numbers.json', 'w') as f:>>     json.dump({'numbers':numbers}, f)>> with open('strings.json', 'w') as f:>>     json.dump({'strings':[str(x) for x in numbers]}, f)>>>>>> $ du -h strings.json numbers.json>> 984K    strings.json>> 788K    numbers.json>>>>>> Marcin>>>> _______________________________________________>> cif-developers mailing list>> cif-developers@iucr.org>> http://mailman.iucr.org/cgi-bin/mailman/listinfo/cif-developers>>>>>> --> Robert M. Hanson> Larson-Anderson Professor of Chemistry> St. Olaf College> Northfield, MN> http://www.stolaf.edu/people/hansonr>>> If nature does not answer first what we want,> it is better to take what answer we get.>> -- Josiah Willard Gibbs, Lecture XXX, Monday, February 5, 1900>>> _______________________________________________> cif-developers mailing list> cif-developers@iucr.org> http://mailman.iucr.org/cgi-bin/mailman/listinfo/cif-developers>_______________________________________________cif-developers mailing listcif-developers@iucr.orghttp://mailman.iucr.org/cgi-bin/mailman/listinfo/cif-developers

Reply to: [list | sender only]
International Union of Crystallography

Scientific Union Member of the International Science Council (admitted 1947). Member of CODATA, the ISC Committee on Data. Partner with UNESCO, the United Nations Educational, Scientific and Cultural Organization in the International Year of Crystallography 2014.

International Science Council Scientific Freedom Policy

The IUCr observes the basic policy of non-discrimination and affirms the right and freedom of scientists to associate in international scientific activity without regard to such factors as ethnic origin, religion, citizenship, language, political stance, gender, sex or age, in accordance with the Statutes of the International Council for Science.