compare

问题 This question already has answers here : Remove constant columns with or without NAs (7 answers) How to remove data frame column with a single value (3 answers) Closed 5 months ago . I am given a large data.table, which has columns of different types: e.g. numeric or character. E.g. data.table(name=c("A","A"),val1=c(1,2),val2=c(3,3),cat=c("u","v")) name val1 val2 cat 1: A 1 3 u 2: A 2 3 v As a results, I would like a data.table just with the columns, where the entries are different between

问题 I've a class class BarBase { }; and a derived template class, which stores a pointer to a member function and a pointer to an object of the same class template<typename TypeName> class Bar: public BarBase { void ( TypeName::*action ) ( void ); TypeName* object; }; I create instances of Bar and store pointers to them in the vector of another class Foo class Foo { private: vector<BarBase*> myBars; ... }; Now to the question. Foo has a template function template <typename TypeName> void Foo::foo

问题 So I have a one liner: import decimal; h = decimal.Decimal('100.0'); (h > .01, h < .01, h.__gt__(.01), h.__lt__(.01)) All it does is make a Decimal object holding 100.0, and compares it to .01 (the float) in various ways. My result is: >>> import decimal; h = decimal.Decimal('100.0'); (h > .01, h < .01, h.__gt__(.01), h.__lt__(.01)) (False, True, NotImplemented, NotImplemented) From the docs: "A rich comparison method may return the singleton NotImplemented if it does not implement the

问题 (Also posted on the Lua mailing list) So I've been writing deep-copy algorithms, and I wanna test them to see if they work the way I want them to. While I do have access to the original->copy map, I want a general-purpose deep-compare algorithm that must be able to compare table keys (tables as keys?). My deep-copy algorithm(s) are avaliable here: https://gist.github.com/SoniEx2/fc5d3614614e4e3fe131 (it's not very organized, but there are 3 of them, one uses recursive calls, the other uses a

问题 is there anyway to compare two strings regardless of case size? For Example "steve" eq "STevE" <----- these would match "SHOE" eq "shoe" You get the picture 回答1: yes - use uc() (upper-case function; see http://perldoc.perl.org/functions/uc.html ) $ perl -e 'print uc("steve") eq uc("STevE"); print "\n";' 1 $ perl -e 'print uc("SHOE") eq uc("shoe"); print "\n";' 1 $ perl5.8 -e 'print uc("SHOE") eq uc("shoe1"); print "\n";' $ You can obviously use lc() as well. If you want the actual "eq"

问题 I already read date functions but i cant think a best way to solve my problem. I have a couple of dates from database which is String and i want to compare it to may current date. I am using the compareTo , but there is a problem using this function i guess it is because of i was comparing strings. This is my function: public int dateCompare(String today, String date2){ return today.compareTo(date2); } And when i use it in sample dates: dateCompare("04/19/2013","04/18/2013"); it returns 1,

问题 I'm working on a desktop Java application. It needs to check for a specific file on my S3 server. I don't want to download the entire file to compare, I need to find out if the one in the server is newer then the local one and then download and replace. I'm not sure how to do the check if newer available part of this. I've heard of hashing as a method but I have little experience with how to actually do that on both fronts (locally and via S3) 回答1: To get the hash of the remote file: How to

问题 I have 2000 rows of data for 4000 columns. What I'm trying to do is to compare each row to the rest of the rows and see how similar they are in terms of different columns/total columns. What I did so far is as follows: for (i in 1:nrow(data)) { for (j in (i+1):nrow(data)) { mycount[[i,j]] = length(which(data[i,] != data[j,])) } } There are 2 problems with it, j doesn't start from i+1 (which is probably a basic mistake) The main problem however is time it consumes, it takes ages... Could

问题 I'm creating a part scanner in C that pulls all possibilities for scanned parts as images in a directory. My code currently fetches all images from that directory and dumps them into a vector. I then produce groups of contours for all the images. The program then falls into a while loop where it constantly grabs images from a webcam, and generates contours for those as well. I have set up a jig for the part to rest on, so orientation and size are not a concern, however I don't want to have to