1
我有一个方法从lua中的父列表指针构建树。 特别我有此LUA表为什么传递参数到lua类方法得到nill
parents = {2,3,13,5,12,7,11,9,10,11,12,13,14,0}
随着两个功能:
功能1(将产生的节点):
function create_node(parent, i, created, root)
if created[i] ~= nil then
return
end
print(i)
-- print(parent)
-- Create a new node and set created[i]
local new_node = Tree()
new_node.idx = i
created[i] = new_node
-- If 'i' is root, change root pointer and return
if parent[i] == 0 then
root[1] = created[i] -- root[1] denotes root of the tree
return
end
-- If parent is not created, then create parent first
if created[parent[i]] == nil then
create_node(parent, parent[i], created, root)
end
print(i)
-- Find parent pointer
local p = created[parent[i]]
print (p)
if #p.children <=2 then
print(p.idx)
print(created[i].idx)
p.add_child(created[i])
end
end
功能2(创建树递归地): 我已经停止了一个循环牛逼从叶的第一路径为根即1-2-3-13-14
function read_postorder_parent_tree(parents)
n = #parents
-- Create and array created[] to keep track
-- of created nodes, initialize all entries as None
created = {}
root = {}
for i=1, 1 do
create_node(parents, i, created, root)
end
return root[1]
end
的create_note
方法是使用下面的Tree
类:
local Tree = torch.class('Tree')
function Tree:__init()
self.parent = nil
self.num_children = 0
self.children = {}
end
function Tree:add_child(c)
print(c)
c.parent = self
self.num_children = self.num_children + 1
self.children[self.num_children] = c
end
一切工作正常,但是当我打电话p.add_child(created[i])
这个说法是nil
为什么? (为什么c
是nil
?)我已经检查过created[i]
和p
不是nil
。我如何解决这个问题和/或为什么会发生这种情况?
这是我的错误:
./Tree.lua:16: attempt to index local 'c' (a nil value)
stack traceback:
./Tree.lua:16: in function 'add_child'
main.lua:120: in function 'create_node'
main.lua:109: in function 'create_node'
main.lua:109: in function 'create_node'
main.lua:109: in function 'create_node'
main.lua:134: in function 'read_postorder_parent_tree'
main.lua:153: in function 'main'
main.lua:160: in main chunk
[C]: in function 'dofile'
...3rto/torch/install/lib/luarocks/rocks/trepl/scm-1/bin/th:150: in main chunk
[C]: at 0x00405d50
提供了实际的错误信息,而不是你的解释。 – Piglet
@Piglet我张贴它 – sdrabb