def choose_features(features, hrs=True, numlocs=True, location=True, latlon=True):
    """
    Returns a list of feature names chosen from the dictionary "features"
    
    Parameters:
    features: a dictionary with keys equal to the arguments of the function, values list of df variables
    hrs: If True, choose feature group that contains hours spent in Tuscany, hours spent outside Tuscany
    numlocs: If True, choose feature group that contains number of locations and number of unique locations visited in Tuscany and Italy
    location: If True, choose feature group that contains time spent (in mumtiples of ) at the locations with respective features, including landscape, cities visited, and total number of attactions visited.
    latlon: If True, choose feature group that contains latitude and longitude of average location, most visited location, start and end location, and standard deviation of all lat/lon
    """
    final_features=[]
    options = [hrs, numlocs, location, latlon]
    for f in zip(options,features.keys()):
        #print (f)
        if f[0]==True:
            final_features.extend(features[f[1]])
    return final_features