遍历python中的列表

Question

I want to iterate through a list of lists in python. I print all the values first, then subsequent iterations, I delete the last value, for example:

mylists=[["near", "belle", "round", "about"],[" vue"," bus"," stop"],["sammy"],["mombasa","road"]]

In the above list, I print:

"near belle round about"
"near belle round"
"near belle"
"near"

and continue with all the other lists.

Kindly help me with the best way to do this, I have the following code which doesn't give me what I want.

for list in sentence:

    while len(list) >0:
        print list.pop()

Answer 1

You're printing the return from pop , but it sounds like you want what's left after the pop . Try this:

for alist in mylists:           # Use alist, not list, to avoid shadowing list built-in
    while alist:                 # Faster equivalent to while len(alist) > 0:
        print(' '.join(alist))   # Join and print current value
        alist.pop()              # Remove last, finished when emptied

Your question title asks about doing this recursively, but your attempt wasn't recursive, and which step you intend to be recursive is somewhat unclear; the problem doesn't require recursion at all.

Answer 2

using a nested list comprehension:

[[' '.join(x[:i]) for i in range(len(x), 0, -1)] for x in mylists]

You could use print if you don't want the output:

[[print(' '.join(x[:i])) for i in range(len(x), 0, -1)] for x in mylists];

nb use xrange if using python 2

Answer 3

for list in mylists:     #iterator for outer list
    while len(list) >0:  #iterator for inner list , length of inner list > 0
        print list       #print elements in the inner list 
        list.pop()       #pop the last element of the inner list