Codewars kata: Calculate mean and concatenate string

kata_mean_concat.py

"""
Return an array of length 2 with a[0] representing the mean of the ten integers as a floating point number. 
There will always be 10 integers and 10 characters. Create a single string with the characters and 
return it as a[1] while maintaining the original order.
"""
def mean(lst):

    #split list into integers and strings
    lst_mean = [int(i) for i in lst if i.isdigit()]
    lst_str = list(filter(lambda x: not x.isdigit(), lst))
    
    #return arr[float, str]
    return [sum(lst_mean)/len(lst_mean), ''.join(lst_str)]