equality

问题 I found a considerable answer from this post: Is there an easy way to pickle a python function (or otherwise serialize its code)? however, the restored function seems slightly different from the original one, which fails my test. Here's the sample code: import marshal # serialize f1 = lambda x: x == 0 c1 = marshal.dumps(f1.func_code) # deserialize f2 = types.FunctionType(c1, globals()) # test c1 = marshal.dumps(f1.func_code) c2 = marshal.dumps(f2.func_code) assert c1 == c2 # fails Do you have

问题 I'm currently writing an aggregation query for MongoDB in my Spring project in which I'm using $project operator. Within this operator I would like to compare two fields in order to return the result as projected "matches" key value. Here's the mongoDB shell equivalent (which works): {$project: {matches: {$eq: ["$lastDate", "$meta.date"]} } } I've read Spring Data MongoDB documentation and found some useful info about ProjectionOperator's 'andExpression' method which uses SpEL. The result

问题 I have two lists in the following format: list1 = ['A','B','C','D'] list2 = [('A',1),('B',2),('C',3)] I want to compare the two lists and print out a third list which will have those elements present in list1 but not in list2 and I want to compare only the list2[i][0] elements. I tried the below code: fin = [i for i in list1 if i not in list2] But it prints all the elements in list1. I want the output in the above case to be : fin = ['D'] Could somebody please suggest how to do that? Also, I

问题 If I want to compare two values for equality there are a number of options, such as: eq for symbols = for numbers char-equal for characters string-equal for strings eql for symbols, numbers and strings equal for everything but symbols … (And I hope I got this right so far.) Now, as a Lisp beginner, my question is: Why is that? Is this just for "historical reasons" or is there a real benefit of having all these possibilities? I know that why -questions are always hard to answer and may be

问题 Given the following expression, how can I use = to be more concise and explicit? (//h2/@id[contains(.,"foo") or contains(.,"bar") or contains(.,"baz"))[last()] Here's what I tried, but my interpreter says it's not valid: (//h2/@id[text() = ("foo", "bar", "baz")])[last()] I cannot use contains() because I need to guard against substring matches. I'm using XPath 1.0 and an answer to a related question is the impetus for this question. 回答1: In XPath 2.0, //h2[@id = ("foo", "bar", "baz")][last()]

问题 My problem is ContainsKey is always returning false even when they key has been added and .Equals evaluates to true. I have the following class: public class StatisticsFilter { private String someString1; private String someString2; ..... public override string ToString() { return string.Format("{0}-{1}-{2}-{3}-{4}", someString1, someString2, ...) } public override bool Equals(object obj) { return obj.ToString().Equals(ToString()); } public override int GetHashCode() { return ToString()

问题 From: http://www.2ality.com/2011/12/strict-equality-exemptions.html JavaScript has two operators for determining whether two values are equal: The strict equality operator === only considers values equal that have the same type. The “normal” (or lenient) equality operator == tries to convert values of different types, before comparing like strict equality. The advice given to JavaScript beginners is to completely forget about == and to always use ===. But what is the reason behing it for not

问题 I am still wondering what it means that a term of the equality type eq in COQ can be different from eq_refl . Is the following term an example for this? ((fun x:nat => eq_refl x) 2). This term is syntactically different from eq_refl , but nevertheless it computes to eq_refl . Does there exist examples of terms which do not compute to eq_refl ? P.S. Its not a homework question ;-) 回答1: As you point out, (fun x => eq_refl x) 2 is not actually different from eq_refl 2 , since both expressions

问题 Question Do the values returned by rgeos::gCentroid() and sf::st_centroid() differ? If so, how? Context After reading the relevant commands exported by rgeos section within the r-spatial/sf wiki, I was thrilled to see that I only needed the sf package - and no longer needed to import the rgeos package - to calculate the centroid of a given geometry. However, the use of sf::st_centroid() gave me this warning, which is addressed here: Warning message: In st_centroid.sfc(x = comarea606$geometry)

问题 In versions of .net prior to 4.0, if a structure contained only primitive fields, the Equals operator for the struct would only return true if all fields matched precisely. In 4.0, Microsoft changed this behavior so that structures with fields of type Decimal could return true if the corresponding fields held values representing the same numerical quantity, even if they did not match in other details (most notably, for Decimal , values which differed only in trailing zeroes were considered