What is the most efficient string concatenation method in python?

Question

Is there any efficient mass string concatenation method in Python (like StringBuilder in C# or StringBuffer in Java)? I found following methods here:

• Simple concatenation using +
• Using string list and join method
• Using UserString from MutableString module
• Using character array and the array module
• Using cStringIO from StringIO module

But what do you experts use or suggest, and why?

[A related question here]

Answer 1

You may be interested in this: An optimization anecdote by Guido. Although it is worth remembering also that this is an old article and it predates the existence of things like ''.join (although I guess string.joinfields is more-or-less the same)

On the strength of that, the array module may be fastest if you can shoehorn your problem into it. But ''.join is probably fast enough and has the benefit of being idiomatic and thus easier for other python programmers to understand.

Finally, the golden rule of optimization: don't optimize unless you know you need to, and measure rather than guessing.

You can measure different methods using the timeit module. That can tell you which is fastest, instead of random strangers on the internet making guesses.