Comparing for greater/smaller is not really a problem unless you’re working right at the edge of the float/double precision limit. For a “fuzzy equals” comparison, this (Java code, should be easy to adapt) is what I came up with for The Floating-Point Guide after a lot of work and taking into account lots of criticism: … Read more
Below are three approaches to solving this problem (and there are many others). The first is a standard approach in computer vision, keypoint matching. This may require some background knowledge to implement, and can be slow. The second method uses only elementary image processing, and is potentially faster than the first approach, and is straightforward … Read more
From the docs: The comparison uses lexicographical ordering: first the first two items are compared, and if they differ this determines the outcome of the comparison; if they are equal, the next two items are compared, and so on, until either sequence is exhausted. Also: Lexicographical ordering for strings uses the Unicode code point number … Read more
When you compile a number literal in Java and assign it to a Integer (capital I) the compiler emits: Integer b2 =Integer.valueOf(127) This line of code is also generated when you use autoboxing. valueOf is implemented such that certain numbers are “pooled”, and it returns the same instance for values smaller than 128. From the … Read more
Date has before and after methods and can be compared to each other as follows: if(todayDate.after(historyDate) && todayDate.before(futureDate)) { // In between } For an inclusive comparison: if(!historyDate.after(todayDate) && !futureDate.before(todayDate)) { /* historyDate <= todayDate <= futureDate */ } You could also give Joda-Time a go, but note that: Joda-Time is the de facto standard … Read more
I was a member of the IEEE-754 committee, I’ll try to help clarify things a bit. First off, floating-point numbers are not real numbers, and floating-point arithmetic does not satisfy the axioms of real arithmetic. Trichotomy is not the only property of real arithmetic that does not hold for floats, nor even the most important. … Read more
Assuming ASCII strings: string1 = ‘Hello’ string2 = ‘hello’ if string1.lower() == string2.lower(): print(“The strings are the same (case insensitive)”) else: print(“The strings are NOT the same (case insensitive)”) As of Python 3.3, casefold() is a better alternative: string1 = ‘Hello’ string2 = ‘hello’ if string1.casefold() == string2.casefold(): print(“The strings are the same (case insensitive)”) … Read more
From the python 2 manual: CPython implementation detail: Objects of different types except numbers are ordered by their type names; objects of the same types that don’t support proper comparison are ordered by their address. When you order two strings or two numeric types the ordering is done in the expected way (lexicographic ordering for … Read more
TL;DR I have always successfully sorted my arrays like this No, you have not. And didn’t notice it. A quick counterexample: > [1,1,0,2].sort(function(a, b){ return a>b }) Array [0, 1, 2, 1] // in Opera 12. Results may vary between sorting algorithm implementations why? Because your comparison function does return false (or 0, equivalently) even … Read more
is is identity testing, == is equality testing. what happens in your code would be emulated in the interpreter like this: >>> a=”pub” >>> b = ”.join([‘p’, ‘u’, ‘b’]) >>> a == b True >>> a is b False so, no wonder they’re not the same, right? In other words: a is b is the … Read more