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In R, there is a rather useful replace function. Essentially, it does conditional re-assignment in a given column of a data frame. It can be used as so: replace(df$column, df$column==1,'Type 1'); What is a good way to achieve the same in pandas? Should I use a lambda with apply ? (If so, how do I get a reference to the given column, as opposed to a whole row). Should I use np.where on data_frame.values ? It seems like I am missing a very obvious thing here. Any suggestions are appreciated. pandas has a replace method too: In [25]: df = DataFrame({1: [2,3,4], 2: [3,4,5]}) In [26]: df Out[26]: 1

Possible Duplicate: Splitting a string in C++ In PHP, the explode() function will take a string and chop it up into an array separating each element by a specified delimiter. Is there an equivalent function in C++? Here's a simple example implementation: #include <string> #include <vector> #include <sstream> #include <utility> std::vector<std::string> explode(std::string const & s, char delim) { std::vector<std::string> result; std::istringstream iss(s); for (std::string token; std::getline(iss, token, delim); ) { result.push_back(std::move(token)); } return result; } Usage: auto v = explode(

Is there a way to do the following preprocessor directives in Python? #if DEBUG < do some code > #else < do some other code > #endif There's __debug__ , which is a special value that the compiler does preprocess. if __debug__: print "If this prints, you're not running python -O." else: print "If this prints, you are running python -O!" __debug__ will be replaced with a constant 0 or 1 by the compiler, and the optimizer will remove any if 0: lines before your source is interpreted. Evan Plaice I wrote a python preprocessor called pypreprocessor that does exactly what you're describing. The

Q: Do we have anything functionally equivalent in Python to the Ruby version manager 'rvm' ? ( RVM lets you easily switch completely between different versions of the ruby interpreter and different sets of gems (modules). Everything concerning download-build-install-switch of interpreter(-s) and gems gets taken care of by invoking rvm. It is all run under your regular user account.) Yes, it is virtualenv along with virtualenvwrapper . update: you may install both at once with virtualenv burrito . Update : the correct answer is now probably pyenv . For scientific computing, the corresponding

This question already has an answer here: How to get the first non-null value in Java? 12 answers Possible Duplicate: How to get the first non-null value in Java? Is it possible to do something similar to the following code in Java int y = x ?? -1; more about ?? Sadly - no. The closest you can do is: int y = (x != null) ? x : -1; Of course, you can wrap this up in library methods if you feel the need to (it's unlikely to cut down on length much), but at the syntax level there isn't anything more succinct available. ColinD Guava has a method that does something similar called MoreObjects

I have a class with some static members, and I want to run some code to initialize them (suppose this code cannot be converted into a simple expression). In Java, I would just do class MyClass { static int myDatum; static { /* do some computation which sets myDatum */ } } Unless I'm mistaken, C++ does not allow for such static code blocks, right? What should I be doing instead? I would like solution for both of the following options: Initialization happens when process loads (or when the DLL with this class is loaded). Initialization happens when the class is first instantiated. For the second