Reorder a list based on order from another list of a different length-CodePudding

Given two lists:

listA = ['apples','bananas','peaches','orange']
ListB = ['peaches','apples']

How do I reformat listA so that the items that are in both lists appear in the order from listB.

For example:

Result = ['peaches','bananas','apples','orange']

The rest of the values should maintain their position.

CodePudding user response：

Create an iterator for list B, iterate through list A, if the item occurs in list B, read from the iterator, else use the item as is:

>>> a = ['apples','bananas','peaches','orange']
>>> b = ['peaches','apples']
>>> it_b = iter(b)
>>> [next(it_b) if i in b else i for i in a]
['peaches', 'bananas', 'apples', 'orange']

Optionally: first clean list B to only contain values occurring in list A.

CodePudding user response：

Start with a copy of list_b and insert the missing values at the appropriate places. If you have bigger lists there might be better options concerning the performance.

list_a = ['apples', 'bananas', 'peaches', 'orange']
list_b = ['peaches', 'apples']

result = list_b.copy()

for index, value in enumerate(list_a):
    if value not in list_b:
        result.insert(index, value)

print(result)