Use multi-axis indexing, e.g. df.loc[‘a’, ‘1’] When you use df[‘1’][‘a’], you are first accessing the series object s = df[‘1’], and then accessing the series element s[‘a’], resulting in two __getitem__ calls, both of which are heavily overloaded (handle a lot of scenarios, like slicing, boolean mask indexing, and so on). It’s much more efficient … Read more
Servlet filters are implementation of the chain of responsibility pattern The point is that each filter stays “in front” and “behind” each servlet it is mapped to. So if you have a filter around a servlet, you’ll have: void doFilter(..) { // do stuff before servlet gets called // invoke the servlet, or any other … Read more
Sure, the trick is to return the object once you’re done modifying it: String.prototype.foo = function() { return this + “+”; } var str = “Notepad”; console.log(str.foo().foo().toUpperCase()); http://jsfiddle.net/Xeon06/vyFek/ To make the method available on String, I’m modifying it’s prototype. Be careful not to do this on Object though, as it can cause problems when enumerating … Read more
You are illustrating the different between chaining and branching. Chaining wil sequence multiple async operations so one starts when the prior one finishes and you can chain an arbitrary number of items to sequence one after the other. Branching hooks up multiple async operations to all be in flight at the same time when one … Read more
Sounds like you want to branch, not to break – you want to continue as usual to the done. A nice property of promises is that they don’t only chain, but also can be nested and unnested without restrictions. In your case, you can just put the part of the chain that you want to … Read more