new = old[:]Those proficient in Python know what the previous line do. It copies the list old into new. This is confusing for beginners and should be avoided. Sadly the [:] notation is widely used, probably because most Python programmers don’t know a better way of copying lists.A little bit of pythonic theoryFirst we need to understand how Python manages objects & variables. Python doesn’t have variables like C. In C a variable is not just a name, it is a set of bits; a variable exists somewhere in memory. In Python variables are just tags ...

Now that you have you system and project environment all setup you probably want to start developing. But you likely don’t want to start writing an entire project fully from scratch, as you dive in you’ll quickly realize theres many tools helping you build projects and sites faster. For example making a request to a website there’s Requests, for handling processing images there’s Python Imaging Library, or for a full framework to help you in building a site there’s Django. With all of these there’s one simple and common way to install ...

The Ruby language is beautiful. And I think it deserves to break free from the Web. I think the future of Ruby is firmly stuck in Web development, though, so I’m going to invest in a new language for data analysis, at least for now. This is a look at the fantastic language I came to from Java and a look at a possible candidate. (Update: I’ve since written a followup.)Java to RubySix years ago, I added Ruby to my technical arsenal. I learned C++ and Java in high school, and I planned to use them for data analysis in college—mainly for research kung fu. But when I disco...

I've found, contrary to what you sometimes read, that learning Python and Haskell has not improved my programming using other languages. Haskell in particular, being so different from imperative languages, is supposed to give new insights into programming that will help you even when you are not using the language. My current experience doesn't exactly tally with this, and here is why:Demotivation.I find I think in Python, and even in Haskell to some extent, even though I have used Haskell very little. I constantly find myself wanting to use idioms from these languages, or noticing h...

Hi! I’m Pavel and I interned at Dropbox over the past summer. One of my biggest projects during this internship was optimizing Python for dynamic page generation on the website. By the end of the summer, I optimized many of dropbox.com’s pages to render 5 times faster. This came with a fair share of challenges though, which I’d like to write about today:The ProblemDropbox is a large website with lots of dynamically generated pages. The more pages that are dynamically generated from user input, the bigger the risk becomes for Cross-site scriptingattacks. To prevent thi...