Python：在 for 循环外和循环内添加到列表列表

Question

我想在 for 循环之外创建一个索引值为 0 的新列表，然后使用 for 循环添加到同一个列表。我的玩具示例是：

import random

data = ['t1', 't2', 't3']

masterlist = [['col1', 'animal1', 'animal2', 'animal3']]
animals = ['cat', 'dog', 'chinchilla']

for item in data:
    masterlist.append([item])
    for animal in animals:
        number1 = random.randint(1, 100)
        number2 = random.randint(1, 100)
        masterlist.append([str(number1) + ',' + str(number2)])

masterlist

但这输出：

[['col1', 'animal1', 'animal2', 'animal3'],
 ['t1'],
 ['52,69'],
 ['8,77'],
 ['75,66'],
 ['t2'],
 ['67,33'],
 ['85,60'],
 ['98,12'],
 ['t3'],
 ['60,34'],
 ['25,27'],
 ['100,25']]

我想要的输出是：

[['col1', 'animal1', 'animal2', 'animal3'],
 ['t1', '52,69', '8,77', '75,66'], 
 ['t2', '67,33', '85,60', '98,12'],
 ['t3', '60,34', '25,27', '100,25']]

Answer 1

这个稍微重构了您的代码的解决方案怎么样？

解决方案 1

import random

data = ['t1', 't2', 't3']

masterlist = [['col1', 'animal1', 'animal2', 'animal3']]
animals = ['cat', 'dog', 'chinchilla']

for item in data:
    rv = []
    rv.append(item)
    for animal in animals:
        number1 = random.randint(1, 100)
        number2 = random.randint(1, 100)
        rv.append(str(number1) + ',' + str(number2))
    masterlist.append(rv)

输出：

>>> masterlist
[['col1', 'animal1', 'animal2', 'animal3'],
 ['t1', '88,43', '85,62', '84,21'],
 ['t2', '44,99', '32,54', '83,50'],
 ['t3', '82,87', '90,83', '91,84']]

或者，以下将给出相同的结果。

解决方案 2

import random

data = ['t1', 't2', 't3']

masterlist = [['col1', 'animal1', 'animal2', 'animal3']]
animals = ['cat', 'dog', 'chinchilla']

for item in data:
    masterlist.append([item] + [f"{random.randint(1, 100)},{random.randint(1, 100)}" for animal in animals])

Answer 2

你可以这样做。使用 temp 列表来存储每次迭代的项目。此外，您在附加时使用了很多方括号，这导致了嵌套过多的列表。

import random

data = ['t1', 't2', 't3']

masterlist = [['col1', 'animal1', 'animal2', 'animal3']]
animals = ['cat', 'dog', 'chinchilla']

for item in data:
    temp = []
    temp.append(item)
    for animal in animals:
        number1 = random.randint(1, 100)
        number2 = random.randint(1, 100)
        temp.append(str(number1) + ',' + str(number2))
    masterlist.append(temp)

print(masterlist)

Answer 3

您还可以按如下方式使用列表理解：

import random

data = ['t1', 't2', 't3']

masterlist = [['col1', 'animal1', 'animal2', 'animal3']]
animals = ['cat', 'dog', 'chinchilla']

for d in data:
     rv = [d] + [str(random.randint(1, 100)) + ',' + str(random.randint(1, 100)) for a in animals]

masterlist.append(rv)

或者在单个列表理解中更硬核：

masterlist+= [[d] + [str(random.randint(1, 100)) + ',' + str(random.randint(1, 100)) for a in animals] for d in data]

Python：在 for 循环外和循环内添加到列表列表

Python: adding to list of lists both out and in a for loop

python

random

for-loop

list

nested-lists

解决方案 1

解决方案 2