大约有 47,000 项符合查询结果（耗时：0.0457秒） [XML]
Principal component analysis in Python
I'd like to use principal component analysis (PCA) for dimensionality reduction. Does numpy or scipy already have it, or do I have to roll my own using numpy.linalg.eigh ?
...
The simplest possible JavaScript countdown timer? [closed]
Just wanted to ask how to create the simplest possible countdown timer.
3 Answers
3
...
C++ performance challenge: integer to std::string conversion
Can anyone beat the performance of my integer to std::string code, linked below?
13 Answers
...
Convert column classes in data.table
I have a problem using data.table: How do I convert column classes? Here is a simple example: With data.frame I don't have a problem converting it, with data.table I just don't know how:
...
How do I horizontally center an absolute positioned element inside a 100% width div? [duplicate]
In the example below, #logo is positioned absolutely and I need it to be horizontally centered within #header . Normally, I would do a margin:0 auto for relatively positioned elements but I am stuck here. Can someone show me the way?
...
Regular expression for a hexadecimal number?
How do I create a regular expression that detects hexadecimal numbers in a text?
11 Answers
...
Floating point vs integer calculations on modern hardware
I am doing some performance critical work in C++, and we are currently using integer calculations for problems that are inherently floating point because "its faster". This causes a whole lot of annoying problems and adds a lot of annoying code.
...
Which SQL query is faster? Filter on Join criteria or Where clause?
Compare these 2 queries. Is it faster to put the filter on the join criteria or in the WHERE clause. I have always felt that it is faster on the join criteria because it reduces the result set at the soonest possible moment, but I don't know for sure.
...
How to check with javascript if connection is local host?
I want to have a check in my javascript if the page loading up is on my local machine.
12 Answers
...
Display numbers with ordinal suffix in PHP
I want to display numbers as follows
15 Answers
15
...