Python Data Analysis

Calling C code

We can call C functions from Cython. The C string strlen() function is the equivalent of the Python len() function. Call this function from a Cython .pyx file by importing it as follows:

from libc.string cimport strlen

We can then call strlen() from somewhere else in the .pyx file. The .pyx file can contain any Python code. Have a look at the cython_module.pyx file in this book's code bundle:

from collections import defaultdict from nltk.corpus import stopwords from nltk.corpus import names from libc.string cimport strlen sw = set(stopwords.words('english')) all_names = set([name.lower() for name in names.words()]) def isStopWord(w): return w in sw or strlen(w) == 1 or not w.isalpha() or w in all_names def filter_sw(words): return ...