矩阵作为字典;是安全吗？ [英] Matrix as a dictionary; is it safe?

问题描述

我知道密钥的顺序不能保证，这样做还可以，但究竟是什么意思，值的顺序是不能保证的？

I know that the order of the keys is not guaranteed and that's OK, but what exactly does it mean that the order of the values is not guaranteed as well^*?

例如，我将矩阵表示为字典，如下所示：

For example, I am representing a matrix as a dictionary, like this:

signatures_dict = {}
M = 3
for i in range(1, M):
    row = []
    for j in range(1, 5):
        row.append(j)
    signatures_dict[i] = row
print signatures_dict

我的矩阵列是否正确构造？假设我有3行，在这个 signatures_dict [i] =行行，行将始终有1，2 ，3，4，5.什么将 signatures_dict be？

Are the columns of my matrix correctly constructed? Let's say I have 3 rows and at this signatures_dict[i] = row line, row will always have 1, 2, 3, 4, 5. What will signatures_dict be?

1 2 3 4 5
1 2 3 4 5
1 2 3 4 5

或类似

1 2 3 4 5
1 4 3 2 5
5 1 3 4 2

？我担心跨平台支持。

在我的应用程序中，行是单词和列文档，所以我可以说第一列是第一个文件？

In my application, the rows are words and the columns documents, so can I say that the first column is the first document?

* _{python字典中的键（）和值（）的顺序是否保证相同？} / p>

*_{Are order of keys() and values() in python dictionary guaranteed to be the same?}

推荐答案

您将保证每一行都有 1 2 3 4 5 。它不会重新排序它们。缺少 values（）的排序是指如果您调用 signatures_dict.values（），则值可以以任何顺序出来。但值是行，而不是每行的元素。每一行都是一个列表，列表维护它们的顺序。

You will guaranteed have 1 2 3 4 5 in each row. It will not reorder them. The lack of ordering of values() refers to the fact that if you call signatures_dict.values() the values could come out in any order. But the values are the rows, not the elements of each row. Each row is a list, and lists maintain their order.

如果你想要一个维护订单的dict，Python也有这样一个： https://docs.python.org/2/library/collections.html#collections.OrderedDict

If you want a dict which maintains order, Python has that too: https://docs.python.org/2/library/collections.html#collections.OrderedDict

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