equality-operator

My application needs to compare Series instances that sometimes contain nans. That causes ordinary comparison using == to fail, since nan != nan : import numpy as np from pandas import Series s1 = Series([1,np.nan]) s2 = Series([1,np.nan]) >>> (Series([1, nan]) == Series([1, nan])).all() False What's the proper way to compare such Series? How about this. First check the NaNs are in the same place (using isnull ): In [11]: s1.isnull() Out[11]: 0 False 1 True dtype: bool In [12]: s1.isnull() == s2.isnull() Out[12]: 0 True 1 True dtype: bool Then check the values which aren't NaN are equal (using

In a question regarding the use of typeid is C++, I suggested it could be used to compare types in objects comparison. I haven't seen it done much, but I had Java's equals in mind. Looking into Java a bit more , this seems to be the case: Some say the actual classes of the two objects should be compared, and some say instanceof is the right tool to use, possibly with double dispatch. There are of course cases in which one of the two is definitively more suitable, but at least both options are considered . In C++, OTOH, I could barely find code in which the actual types are compared. On most

if(s.name=="kolkata") { printf("the details"); } if(strcmp((s.name,"kolkata")==0) { printf("the details"); } The first 'if' case has no syntax error still it doesn't work,while the second 'if' case does work very efficiently, why? It is not like the first case doesn't work at all, it just works in a way which is not intended . As per the code, if(s.name=="kolkata") is an attempt to compare the pointers themselves. It does not compare the content of the memory location pointer by these pointers. Coming to the point where you were expecting syntax errors , quoting C11 , chapter 6.5.9, the

This question already has an answer here: Which equals operator (== vs ===) should be used in JavaScript comparisons? 49 answers JavaScript comparison operators: Identity vs. Equality 4 answers Why does the following statement return false in JavaScript? new String('hello') === new String('hello') Pointy Two String objects will always be unequal to each other. Note that JavaScript has string primitive values as well as a String constructor to create wrapper objects. All object equality comparisons (especially with === ) are carried out as a test for reference equality . References to two

Why is === faster than == in PHP? Because the equality operator == coerces, or converts the data type temporarily to see if it's equal to the other operand whereas === ( identity operator ) doesn't need to do any converting whatsoever and thus less work is done, making it faster. === does not perform typecasting, so 0 == '0' evaluates to true , but 0 === '0' - to false . First, === checks to see if the two arguments are the same type - so the number 1 and the string '1' fails on the type check before any comparisons are actually carried out. On the other hand, == doesn't check the type first

Why does {} == false evaluate to false while [] == false evaluates to true in javascript? This is the type conversion that takes place according to the Abstract Equality Comparison Algorithm : {} == false // step 7 {} == ToNumber(false) {} == 0 // step 9 ToPrimitve({}) == 0 "[object Object]" == 0 // step 5 ToNumber("[object Object]") == 0 NaN == 0 // step 1.c.i [] == false // step 7 [] == ToNumber(false) [] == 0 // step 9 ToPrimitve([]) == 0 "" == 0 // step 5 ToNumber("") == 0 0 == 0 // step 1.c.iii References: ToNumber , ToPrimitive And because of this, prefer to use strict comparison. Some