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seen Dec 26 at 7:59

Nov
22
comment What is the principle behind Dispatch?
@Mr.Wizard Yeah, I admit it is a little off-topic. And I was wondering if DeleteCases also use hash table? Because it is fast too.
Nov
22
asked What is the principle behind Dispatch?
Nov
22
awarded  Yearling
Nov
21
comment How to Delete Elements from List1 appearing in List2?
@LeonidShifrin and I found that though Complement sort result, but it's even faster then DeleteCases when I test large list!
Nov
21
comment How to Delete Elements from List1 appearing in List2?
@LeonidShifrin I am curious about the principle of DeleteCases. Why is it so fast than Select[list1, FreeQ[list2, #] &]? And I don't know the principle of Dispatch either. May be they have the same principle?
Nov
21
comment How to delete mirror symmetric point pair efficiently
@MichaelE2 You're right. But anyway, the answers contain methods tackle both general case and specific case.
Nov
21
comment Removing reverse versions of lists from a nested list
@LeonidShifrin I understand. Thank you!
Nov
20
comment How to delete mirror symmetric point pair efficiently
clever for getMeTheSymms! Straight and fast for fasterSymms
Nov
20
comment How to delete mirror symmetric point pair efficiently
Oh, I know, n must be odd
Nov
20
comment How to delete mirror symmetric point pair efficiently
why deleteMS didn't give any result on my mathematica?
Nov
20
comment Removing reverse versions of lists from a nested list
@LeonidShifrin f[x_List] := (f[Reverse[x]] = Sequence[]; x); I've never seen this kind of definition before. What is this?
Nov
20
asked How to delete mirror symmetric point pair efficiently
Nov
19
revised when using FileDate----The Creation date of a file is not available on Macintosh and Unix?
added 187 characters in body
Nov
19
comment when using FileDate----The Creation date of a file is not available on Macintosh and Unix?
@george2079 thank you! I found that "Change" option works to distinguish files in Linux
Nov
19
comment Why does Thread FileDate give an error message?
So defining a local variable is inevitable? may be some tricky method?
Nov
19
comment Why does Thread FileDate give an error message?
Position[fdabs, Max[fdabs]]] likes Fold but not the Fold way :)
Nov
19
comment when using FileDate----The Creation date of a file is not available on Macintosh and Unix?
then how can I distinguish two files from the date. If one of the file is just a copy of the other, they have the same modified timestamp.
Nov
19
comment Why does Thread FileDate give an error message?
What is more. If you could refine this line of code, I will be appreciate. Part[#, Flatten@Position[AbsoluteTime /@Thread@FileDate[#],Max[AbsoluteTime /@Thread@FileDate[#]]]] &@FileNames["math*"]. This line of code intends to find the newest created file which has a name contained "math". I just can't eliminate the duplicate in my code, because it will involve pure function in pure function.
Nov
19
comment Why does Thread FileDate give an error message?
Thank you Leonid Shifrin! I found `SetAttribute[FileDate,Listable] works, but I seems to remember a post say setattribute to Listable is not a good way, I can't find the post now, do you know that post?
Nov
19
asked when using FileDate----The Creation date of a file is not available on Macintosh and Unix?