列表的条件合并

Question

我正在尝试根据以下规则合并两个列表：

list1 中的第一个元素应与 list2 中的最后一个元素合并，list1 中的第二个元素应与 list2 中的倒数第二个元素合并，以此类推。

如果 list1/list2 中的元素为 None，则另一个列表中的对应元素应保持在合并列表中的状态。

我觉得我可能必须在这里使用链接列表，但我不确定。我试图通过遍历列表来找出解决方案，但我无法弄清楚这里的逻辑。

def merge_list(list1, list2):
    merged_data=""
    new_str=""
    #write your logic here
    for l1 in list1:
        for l2 in list2[::-1]:
            if l1 is None or l2 is None:
                pass
            else:
                new_str = l1+l2
                i=list2.index(l2)
                print(new_str)
            break
    #return resultant_data


list1=['A', 'app','a', 'd', 'ke', 'th', 'doc', 'awa']
list2=['y','tor','e','eps','ay',None,'le','n']
merged_data=merge_list(list1,list2)
print(merged_data)

预期输出：

“一天一苹果，医生远离我”

Answer 1

您可以使用zip 同时遍历两个列表：

def merge_list(lst1,lst2):
    s = ''
    for x, y in zip(lst1, lst2[::-1]):
        if y and x:
            s += x + y
        elif x:
            s += x
        elif y:
            s += y
        s += ' '
    return s[:-1]

list1 = ['A', 'app','a', 'd', 'ke', 'th', 'doc', 'awa']
list2 = ['y','tor','e','eps','ay',None,'le','n']
merged_data = merge_list(list1,list2)

print(merged_data)
# An apple a day keeps the doctor away

您可以缩短它并使用列表理解，如下所示（但是，我更喜欢另一个更易读的）：

def merge_list(lst1,lst2):
    return ' '.join(x + y if x and y else x if x else y for x, y in zip(lst1, lst2[::-1]))

Answer 2

假设两个列表的长度相同

>>> list1=['A', 'app','a', 'd', 'ke', 'th', 'doc', 'awa']
>>> list2=['y','tor','e','eps','ay',None,'le','n']
>>> ' '.join([l1 + l2 if l1 and l2 else l1 if l1 and not l2 else l2 for l1, l2 in zip(list1, reversed(list2)) if l1 and l2])
'An apple a day keeps the doctor away'

Answer 3

确保列表长度相同，然后只需一个 zip 就足够了。但是用''（空字符串）替换None值

["".join(row) for row in zip(list1, reversed(list2))]

=>

['An', 'apple', 'a', 'day', 'keeps', 'the', 'doctor', 'away']

Answer 4

首先使用list comprehensions合并两个列表，然后将该列表转换为string。

" ".join(str(x) for x in [list1[i]+list2[len(list2)-1-i] if list2[len(list2)-1-i] != None else list1[i] for i in range(len(list1))])
    'An apple a day keeps the doctor away'

Answer 5

def fetch_index(list2, item_index):
    x = list2[::-1]
    return x[item_index]

def merge_list(list1, list2):
    list_3 = []
    #write your logic here
    for l1 in list1:
        l2 = fetch_index(list2, list1.index(l1))
        if l1 is None and l2 is None:
            pass
        elif l1 is None:
            list_3.append(l2)
        elif l2 is None:
            list_3.append(l1)
        else:
            list_3.append(l1+l2)
    return(list_3)

list1=['A', 'app','a', 'd', 'ke', 'th', 'doc', 'awa']
list2=['y','tor','e','eps','ay',None,'le','n']
x = merge_list(list1,list2)
print ' '.join(i for i in x)

如果您不想使用 zip，请使用更长的版本

Answer 6

不使用 zip 的简短回答。

" ".join([list1[x]+[y if y is not None else '' for y in list2 ][::-1][x] for x in range(len(list1)-1)]

Answer 7

list1=['A', 'app','a', 'd', 'ke', 'th', 'doc', 'awa']
list2=['y','tor','e','eps','ay',None,'le','n']
a=list2.remove(None)
list2.insert(5,"")
list3 = [ str(x[0]) + x[1]   for x in zip(list1, list2[::-1]) ]
print ' '.join(list3)

输出：

一天一苹果，医生远离我

Answer 8

l1=['A', 'app','a', 'd', 'ke', 'th', 'doc', 'awa']
l2=['y','tor','e','eps','ay',None,'le','n']
a=l2[::-1]
l3=[]
for i in range(len(l1)):
    if(l1[i] is None or a[i] is None):
        l3.append(l1[i])`enter code here`
    else:
        l3.append(l1[i]+a[i])


print(" ".join(l3))

Answer 9

def merge_list(list1, list2):
merged_data = ""
list3 = list1   
for i in range(1, 2*len(list2) + 1,2):    #Converting both lists in single list
    list3.insert(i, list2[-1])    # Adding last elements of list2 at alternate to positions elements of list3
    list2.pop()  #Removing the last element from list2
list3 = ["" if i is None else i for i in list3]   # Handling NoneType condition. If there is "None", convertted to ""
for i in range(0,len(list3),2):
    word="".join(list3[i:i+2])   #joining the elements in set of two
    merged_data=merged_data+word+" "   #converting above word into one
return merged_data

Answer 10

list1=['A', 'app','a', 'd', 'ke', 'th', 'doc', 'awa']
list2=['y','tor','e','eps','ay',None,'le','n']
s=''
new=''
for i in list1:
    for j in list2[::-1]:
        if i==None:
            i=''
        elif j==None:
            j=''
        new=i+j
        s=s+new+' '
        list2.pop(-1)
        break
print(s)