返回可变数量输出的python函数

Question

I want to input a table of unknown width (number of columns) and I want my function to output a list for each column. I am also outputting a list containing the names of the said lists.

I am trying this:

def crazy_fn(table):  
    titles=read_col_headers(table)  
    for i in range(1,len(table)):   
        for j in range(0,len(titles)):  
            vars()[titles[j]].append(table[i][j])  

    return titles, vars()[titles[k]] for k in range(0,len(titles))

The function works for when I know how many columns/lists I will output (return titles, a, b, c, d), but the way I've tried to generalize is not working.

Answer 1

It's generally a bad idea to have a non-constant number of variables returned from a function, because using it is confusing and error-prone.

Why don't you return a dictionary mapping title headers to the list?

def crazy_fn(table):  
    result=dict()
    titles=read_col_headers(table)
    for title in titles:
        result[title]=VALUE(TITLE)
    return result

This can be abbreviated using dictionary comprehension to:

def crazy_fn(table):
   return {title : VALUE(TITLE) for title in read_col_headers(table)}

Answer 2

Woah, too many loops

something like:

def crazy_fn(table): 
    titles = read_col_headers(table)
    columns = zip(*table[1:])
    return titles, columns

would probably do it. It's worth reading more about how python built in functions work.