Decorator that caches intermediate research dataframes

picklecached.py

CACHE = os.path.dirname(os.path.dirname(os.path.realpath(__file__)))+'/cache/'


def picklecached():
    """
    A function that creates a decorator which will use "cachefile" for caching the results of the decorated function "fn".
    Also stores a CSV so we can quickly inspect the result ... though only pickles are used in loading.
    """
    def decorator(fn):  # define a decorator for a function "fn"
        def wrapped(*args, **kwargs):   # define a wrapper that will finally call "fn" with all arguments
            # if cache exists -> load it and return its content

            # Create a neame for the cache file
            cachefile = CACHE + fn.__name__
            if len(kwargs):
                cachefile += '?'+'&'.join([k+'='+str(v) for k,v in kwargs.items()])
            cachefile += '.pkl'

            # Check if is already exists
            if os.path.exists(cachefile):
                    with open(cachefile, 'rb') as cachehandle:
                        print("Using cached result from '%s'" % cachefile)
                        return pickle.load(cachehandle)

            # execute the function with all arguments passed
            res = fn(*args, **kwargs)

            # write to cache file
            with open(cachefile, 'wb') as cachehandle:
                print("Saving result to cache '%s'" % cachefile)
                pickle.dump(res, cachehandle)
                try:
                    res.to_csv(cachefile.replace('.pkl','.csv'))
                except:
                    print('Could not save CSV but pickle was dumped.')

            return res

        return wrapped

    return decorator