TL; DR 当我追加（或插入）数据时，“错误数据”也会被追加，列表中以前存储的数据似乎也会发生变化。
我在代码中遇到一个非常奇怪的错误，对我来说真的没有意义。
我正在读取一个CSV文件，并且其数据存储为列表（ratio），从该列表中，我使用np.mean()和np.std()来计算均值和标准偏差，以及将它们存储在列表中。在这些计算中，我调用一个函数来检查很多事情，但重要的是：
状态发生变化时，该函数将返回一个列表（称为status，其中第一项为1。如果状态没有变化，则返回的结果也将是一个列表，但第一项为0 。到目前为止，这里的所有内容都可以使用。
因此，我决定将指示状态更改的所有返回（来自提到的函数）（称为crossed）添加到新列表（称为if status[0] == 1:）中，因此print(status)但是不会添加到列表中的数据预期的。
请注意：我在检查status[0] == 1之后添加了一个.append(status)：它按预期返回，下一行是status = [0,0,0,0,0,0,0]
crossed = []
for i in range((len(ratio)-periods+1)):
if i == 0: #Workaround: When i = 0, ratio[-periods-0:0] won't work
mean.append(np.mean(ratio[-periods-i:]))
std.append(np.std(ratio[-periods-i:]))
lower_std.append(mean[-1]-std[-1])
status = check_ratio(ratio[-periods],mean[-1],lower_std[-1],i,status)
if status[0] == 1:
crossed.append(status)
else:
mean.append(np.mean(ratio[-periods-i:-i]))
std.append(np.std(ratio[-periods-i:-i]))
lower_std.append(mean[-1]-std[-1])
status = check_ratio(ratio[-periods-i],mean[-1],lower_std[-1],i,status)
if status[0] == 1:
print (status)
crossed.append(status)
print(crossed)
，而且根本不会附加打印的内容。
print(status) check_ratio（）函数返回包含大量数据的列表，但第一项始终为0或1。
[1, 1, 54, 1.138758865248227, 1.136314650125257, 1.1337690420509274, 1.1312234339765979]
[1, 2, 57, 1.1353429985855727, 1.136314650125257, 1.1337690420509274, 1.1312234339765979]
[1, 3, 68, 1.1337522123893804, 1.136314650125257, 1.1337690420509274, 1.1312234339765979]
[1, -1, 78, 1.1309345594525235, 0, 0, 0]
[1, 1, 127, 1.130847142192477, 1.1304628293233858, 1.1294503731447396, 1.1284379169660932]
[1, 2, 131, 1.1303973913355072, 1.1304628293233858, 1.1294503731447396, 1.1284379169660932]
[1, 0, 135, 1.1335466666666667, 0, 0, 0]
[1, 1, 138, 1.1308163809185396, 1.1296433002012238, 1.128433107660401, 1.1272229151195785]
[1, 2, 139, 1.1282648093529015, 1.1296433002012238, 1.128433107660401, 1.1272229151195785]
[1, -1, 140, 1.1270390684629994, 0, 0, 0]
[1, 1, 142, 1.1255687149255582, 1.1256917189689608, 1.1233910776545415, 1.1210904363401222]
[1, 2, 143, 1.1254230680630128, 1.1256917189689608, 1.1233910776545415, 1.1210904363401222]
[1, 3, 150, 1.1225412014885698, 1.1256917189689608, 1.1233910776545415, 1.1210904363401222]
[1, -1, 154, 1.1210447814197948, 0, 0, 0]
[1, 1, 197, 1.1171276991444958, 1.1161855800851872, 1.1132670986656799, 1.1103486172461723]
[1, 2, 198, 1.1127123608670182, 1.1161855800851872, 1.1132670986656799, 1.1103486172461723]
[1, 0, 203, 1.1246100837937574, 0, 0, 0]
[1, 1, 284, 1.1390154874100347, 1.1381523185174933, 1.1368941197303815, 1.1356359209432696]
[1, 0, 287, 1.1418469131706104, 0, 0, 0]
[1, 1, 292, 1.137294829075651, 1.136934972982161, 1.1354744212606314, 1.134013869539102]
[1, 0, 297, 1.1415675686816016, 0, 0, 0]
[1, 1, 405, 1.135509186838826, 1.1350790378560178, 1.1335324241438416, 1.1319858104316656]
[1, 2, 407, 1.1339004993526909, 1.1350790378560178, 1.1335324241438416, 1.1319858104316656]
[1, 3, 414, 1.1330645161290323, 1.1350790378560178, 1.1335324241438416, 1.1319858104316656]
[1, 0, 429, 1.1365694764439502, 0, 0, 0]
[1, 1, 442, 1.1273146097280056, 1.1267225301265933, 1.1244185615555562, 1.1221145929845189]
[1, 0, 443, 1.1352307739239194, 0, 0, 0]
[1, 1, 487, 1.1294793579340165, 1.1275050776354896, 1.1255123932368172, 1.1235197088381448]
[1, 0, 490, 1.1343246592317224, 0, 0, 0]
[1, 1, 507, 1.1273536042898056, 1.1260499911131632, 1.1238715385874056, 1.121693086061648]
[1, 2, 509, 1.1253301757901448, 1.1260499911131632, 1.1238715385874056, 1.121693086061648]
[1, 0, 521, 1.1303555916720376, 0, 0, 0]
[1, 1, 526, 1.1238224560807943, 1.120965441404663, 1.1181032018014265, 1.11524096219819]
[1, 0, 528, 1.1290014064697609, 0, 0, 0]
[1, 1, 580, 1.1282299098894226, 1.1262199790650198, 1.1233324063904733, 1.1204448337159267]
[1, 2, 586, 1.1258169934640523, 1.1262199790650198, 1.1233324063904733, 1.1204448337159267]
[1, 3, 599, 1.1229769929859992, 1.1262199790650198, 1.1233324063904733, 1.1204448337159267]
[1, 0, 605, 1.131025825922068, 0, 0, 0]
的返回结果是这样的：（请注意，按预期方式，每个列表都以1开头）
print(crossed)现在这是[[0, 3, 68, 1.1337522123893804, 1.136314650125257, 1.1337690420509274, 1.1312234339765979],
[0, 3, 68, 1.1337522123893804, 1.136314650125257, 1.1337690420509274, 1.1312234339765979],
[0, 3, 68, 1.1337522123893804, 1.136314650125257, 1.1337690420509274, 1.1312234339765979],
[1, -1, 78, 1.1309345594525235, 0, 0, 0],
[0, 2, 131, 1.1303973913355072, 1.1304628293233858, 1.1294503731447396, 1.1284379169660932],
[0, 2, 131, 1.1303973913355072, 1.1304628293233858, 1.1294503731447396, 1.1284379169660932],
[1, 0, 135, 1.1335466666666667, 0, 0, 0],
[1, 2, 139, 1.1282648093529015, 1.1296433002012238, 1.128433107660401, 1.1272229151195785],
[1, 2, 139, 1.1282648093529015, 1.1296433002012238, 1.128433107660401, 1.1272229151195785],
[1, -1, 140, 1.1270390684629994, 0, 0, 0],
[0, 3, 150, 1.1225412014885698, 1.1256917189689608, 1.1233910776545415, 1.1210904363401222],
[0, 3, 150, 1.1225412014885698, 1.1256917189689608, 1.1233910776545415, 1.1210904363401222],
[0, 3, 150, 1.1225412014885698, 1.1256917189689608, 1.1233910776545415, 1.1210904363401222],
[1, -1, 154, 1.1210447814197948, 0, 0, 0],
[0, 2, 198, 1.1127123608670182, 1.1161855800851872, 1.1132670986656799, 1.1103486172461723],
[0, 2, 198, 1.1127123608670182, 1.1161855800851872, 1.1132670986656799, 1.1103486172461723],
[1, 0, 203, 1.1246100837937574, 0, 0, 0],
[0, 1, 284, 1.1390154874100347, 1.1381523185174933, 1.1368941197303815, 1.1356359209432696],
[1, 0, 287, 1.1418469131706104, 0, 0, 0],
[0, 1, 292, 1.137294829075651, 1.136934972982161, 1.1354744212606314, 1.134013869539102],
[1, 0, 297, 1.1415675686816016, 0, 0, 0],
[0, 3, 414, 1.1330645161290323, 1.1350790378560178, 1.1335324241438416, 1.1319858104316656],
[0, 3, 414, 1.1330645161290323, 1.1350790378560178, 1.1335324241438416, 1.1319858104316656],
[0, 3, 414, 1.1330645161290323, 1.1350790378560178, 1.1335324241438416, 1.1319858104316656],
[1, 0, 429, 1.1365694764439502, 0, 0, 0],
[1, 1, 442, 1.1273146097280056, 1.1267225301265933, 1.1244185615555562, 1.1221145929845189],
[1, 0, 443, 1.1352307739239194, 0, 0, 0],
[0, 1, 487, 1.1294793579340165, 1.1275050776354896, 1.1255123932368172, 1.1235197088381448],
[1, 0, 490, 1.1343246592317224, 0, 0, 0],
[0, 2, 509, 1.1253301757901448, 1.1260499911131632, 1.1238715385874056, 1.121693086061648],
[0, 2, 509, 1.1253301757901448, 1.1260499911131632, 1.1238715385874056, 1.121693086061648],
[1, 0, 521, 1.1303555916720376, 0, 0, 0],
[0, 1, 526, 1.1238224560807943, 1.120965441404663, 1.1181032018014265, 1.11524096219819],
[1, 0, 528, 1.1290014064697609, 0, 0, 0],
[0, 3, 599, 1.1229769929859992, 1.1262199790650198, 1.1233324063904733, 1.1204448337159267],
[0, 3, 599, 1.1229769929859992, 1.1262199790650198, 1.1233324063904733, 1.1204448337159267],
[0, 3, 599, 1.1229769929859992, 1.1262199790650198, 1.1233324063904733, 1.1204448337159267],
[1, 0, 605, 1.131025825922068, 0, 0, 0]]
返回：
status = check_ratio(ratio[-periods-i],mean[-1],lower_std[-1],i,status)
if status[0] == 1:
crossed.append(status)
print('>> Appended:',crossed[-1])
print(crossed)
它们应该完全匹配，但是实际上只有几个条目匹配，并且某些数据以某种方式重复了（请参阅print（crossed）的第1,2,3行以及5,6和8,9行）那可能吗？它从字面上打印应该添加的行，并附加另一行。
因此，我决定在每次添加附件时都尝试打印，结果确实很奇怪。
status[0]==1我剪切了返回到前几行和最后一行的内容。这是我观察到的：
第一行是正确的（Appended: [1, 1, 54, 1.138758865248227, 1.136314650125257, 1.1337690420509274, 1.1312234339765979]
[[1, 1, 54, 1.138758865248227, 1.136314650125257, 1.1337690420509274, 1.1312234339765979]]
Appended: [1, 2, 57, 1.1353429985855727, 1.136314650125257, 1.1337690420509274, 1.1312234339765979]
[[1, 2, 57, 1.1353429985855727, 1.136314650125257, 1.1337690420509274, 1.1312234339765979], [1, 2, 57, 1.1353429985855727, 1.136314650125257, 1.1337690420509274, 1.1312234339765979]]
Appended: [1, 3, 68, 1.1337522123893804, 1.136314650125257, 1.1337690420509274, 1.1312234339765979]
[[1, 3, 68, 1.1337522123893804, 1.136314650125257, 1.1337690420509274, 1.1312234339765979], [1, 3, 68, 1.1337522123893804, 1.136314650125257, 1.1337690420509274, 1.1312234339765979], [1, 3, 68, 1.1337522123893804, 1.136314650125257, 1.1337690420509274, 1.1312234339765979]]
Appended: [1, -1, 78, 1.1309345594525235, 0, 0, 0]
[[0, 3, 68, 1.1337522123893804, 1.136314650125257, 1.1337690420509274, 1.1312234339765979], [0, 3, 68, 1.1337522123893804, 1.136314650125257, 1.1337690420509274, 1.1312234339765979], [0, 3, 68, 1.1337522123893804, 1.136314650125257, 1.1337690420509274, 1.1312234339765979], [1, -1, 78, 1.1309345594525235, 0, 0, 0]]
Appended: [1, 1, 127, 1.130847142192477, 1.1304628293233858, 1.1294503731447396, 1.1284379169660932]
[[0, 3, 68, 1.1337522123893804, 1.136314650125257, 1.1337690420509274, 1.1312234339765979], [0, 3, 68, 1.1337522123893804, 1.136314650125257, 1.1337690420509274, 1.1312234339765979], [0, 3, 68, 1.1337522123893804, 1.136314650125257, 1.1337690420509274, 1.1312234339765979], [1, -1, 78, 1.1309345594525235, 0, 0, 0], [1, 1, 127, 1.130847142192477, 1.1304628293233858, 1.1294503731447396, 1.1284379169660932]]
Appended: [1, 2, 131, 1.1303973913355072, 1.1304628293233858, 1.1294503731447396, 1.1284379169660932]
），并附加在行中
第二行是正确的，但是第一行（先前已添加）被第二行的2份副本替换了（如何？）
第三行是正确的，但是先前的数据已被第三行的3个副本替换（第二行的行为相同）
第四行是正确的，但是之前的数据已替换掉，但是每个（先前的条目）的第一项都更改为0。（请参阅附录4下方的列表） ）
到此为止，我得到的列表毫无意义。
css: [
'@/assets/css/reset.css',
'@/assets/css/main.scss',
],
modules: [
[
'nuxt-sass-resources-loader',
['./assets/css/main.scss'],
['./assets/css/reset.css']
]
],
这对我来说真的是0。有人可以看到是什么触发了这种奇怪的行为吗？
答案 0 :(得分：1)
如果将列表（或其他可变容器）添加到列表中，并且该列表后来发生了突变，则该突变也将应用于该容器，因为它是相同的列表。如果存在以后发生变异的风险，请传递（或存储）列表的副本以防止此类问题（称为别名）。
# A function that accepts a list and changes it
>>> def f(sts):
... sts[-1] = sts[-1] * 2
... return [x for x in sts]
...
>>> sts = [1]
>>> out = []
# Observe how the _out_ list is not what we expect (ascending powers of two)
>>> for i in range(5):
... sts = f(sts)
... out.append(sts)
... print(out)
...
[[2]]
[[4], [4]]
[[4], [8], [8]]
[[4], [8], [16], [16]]
[[4], [8], [16], [32], [32]]
# If we pass a copy of sts, we get the expected output.
>>> sts = [1]
>>> out = []
>>> for i in range(5):
... sts = f(sts[:])
... out.append(sts)
... print(out)
...
[[2]]
[[2], [4]]
[[2], [4], [8]]
[[2], [4], [8], [16]]
[[2], [4], [8], [16], [32]]