Lua/Torch中的枚举函数

Question

Lua/Torch中的枚举函数

pythonluatorch

3

在Python中，我们使用for i, _ in enumerate(wx):，其中wx是一个行矩阵或表格。在Lua/Torch中，我们如何使用它？有任何枚举函数吗？

- Sibi

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- hjpotter92 · Accepted Answer

在Lua中，你有pairs和ipairs：

pairs (t)
If t has a metamethod __pairs, calls it with t as argument and returns the first three results from the call.

Otherwise, returns three values: the next function, the table t, and nil, so that the construction
for k,v in pairs(t) do body end
will iterate over all key–value pairs of table t.

你也可以使用next，来创建自定义枚举:

next (table [, index])
Allows a program to traverse all fields of a table. Its first argument is a table and its second argument is an index in this table. next returns the next index of the table and its associated value. When called with nil as its second argument, next returns an initial index and its associated value. When called with the last index, or with nil in an empty table, next returns nil. If the second argument is absent, then it is interpreted as nil. In particular, you can use next(t) to check whether a table is empty.

The order in which the indices are enumerated is not specified, even for numeric indices. (To traverse a table in numerical order, use a numerical for.)

The behavior of next is undefined if, during the traversal, you assign any value to a non-existent field in the table. You may however modify existing fields. In particular, you may clear existing fields.