我在C ++中编写了Levenshtein算法
如果我输入：
string s：民主党人
string t：republican
我得到矩阵D填充并且可以在D [10] [8] = 8中读取操作次数（Levenshtein距离）
在填充矩阵之外，我想构建最优解。怎么看这个解决方案？我不知道。
请只写我如何看这个例子。
答案 0 :(得分：36)
答案 1 :(得分：1)
自从我玩它以来已经有好几次了，但在我看来矩阵看起来应该是这样的：
. . r e p u b l i c a n
. 0 1 2 3 4 5 6 7 8 9 10
d 1 1 2 3 4 5 6 7 8 9 10
e 2 2 1 2 3 4 5 6 7 8 9
m 3 3 2 2 3 4 5 6 7 8 9
o 4 4 3 3 3 4 5 6 7 8 9
c 5 5 4 4 4 4 5 6 7 8 9
r 6 5 5 5 5 5 5 6 7 8 9
a 7 6 6 6 6 6 6 6 7 7 8
t 8 7 7 7 7 7 7 7 7 7 8
不要把它视为理所当然。
答案 2 :(得分：1)
这是一个基于mjv答案的VBA算法。 （很好解释，但有些案例不见了。）
Error: Failed to launch renderer
at C:\Vineet\POC\node_modules\html5-to-pdf\src\phantom.coffee:55:35
at Proto.apply (C:\Vineet\POC\node_modules\dnode-protocol\index.js:123:13)
at Proto.handle (C:\Vineet\POC\node_modules\dnode-protocol\index.js:99:19)
at D.dnode.handle (C:\Vineet\POC\node_modules\dnode\lib\dnode.js:140:21)
at D.dnode.write (C:\Vineet\POC\node_modules\dnode\lib\dnode.js:128:22)
at SockJSConnection.ondata (stream.js:31:26)
at emitOne (events.js:96:13)
at SockJSConnection.emit (events.js:188:7)
at Session.didMessage (C:\Vineet\POC\node_modules\sockjs\lib\transport.js:220:25)
at WebSocketReceiver.didMessage (C:\Vineet\POC\node_modules\sockjs\lib\trans-websocket.js:102:40)
at C:\Vineet\POC\node_modules\sockjs\lib\trans-websocket.js:75:22
at .<anonymous> (C:\Vineet\POC\node_modules\faye-websocket\lib\faye\websocket\api\event_target.js:41:7)
at Array.forEach (native)
at EventTarget.dispatchEvent (C:\Vineet\POC\node_modules\faye-websocket\lib\faye\websocket\api\event_target.js:40:33)
at API.receive (C:\Vineet\POC\node_modules\faye-websocket\lib\faye\websocket\api.js:30:10)
at instance._emitFrame (C:\Vineet\POC\node_modules\faye-websocket\lib\faye\websocket\hybi_parser.js:285:44)
at instance.parse (C:\Vineet\POC\node_modules\faye-websocket\lib\faye\websocket\hybi_parser.js:143:18)
at Socket.<anonymous> (C:\Vineet\POC\node_modules\faye-websocket\lib\faye\websocket.js:72:33)
at emitOne (events.js:96:13)
at Socket.emit (events.js:188:7)
at readableAddChunk (_stream_readable.js:172:18)
at Socket.Readable.push (_stream_readable.js:130:10)
at TCP.onread (net.js:542:20)
答案 3 :(得分：0)
我最近使用Levenshtein距离算法的矩阵做了一些工作。我需要生成将一个列表转换为另一个列表的操作。 （这也适用于字符串。）
以下（誓言）测试是否显示您正在寻找的功能？
, "lev - complex 2"
: { topic
: lev.diff([13, 6, 5, 1, 8, 9, 2, 15, 12, 7, 11], [9, 13, 6, 5, 1, 8, 2, 15, 12, 11])
, "check actions"
: function(topic) { assert.deepEqual(topic, [{ op: 'delete', pos: 9, val: 7 },
{ op: 'delete', pos: 5, val: 9 },
{ op: 'insert', pos: 0, val: 9 },
]); }
}
, "lev - complex 3"
: { topic
: lev.diff([9, 13, 6, 5, 1, 8, 2, 15, 12, 11], [13, 6, 5, 1, 8, 9, 2, 15, 12, 7, 11])
, "check actions"
: function(topic) { assert.deepEqual(topic, [{ op: 'delete', pos: 0, val: 9 },
{ op: 'insert', pos: 5, val: 9 },
{ op: 'insert', pos: 9, val: 7 }
]); }
}
, "lev - complex 4"
: { topic
: lev.diff([9, 13, 6, 5, 1, 8, 2, 15, 12, 11, 16], [13, 6, 5, 1, 8, 9, 2, 15, 12, 7, 11, 17])
, "check actions"
: function(topic) { assert.deepEqual(topic, [{ op: 'delete', pos: 0, val: 9 },
{ op: 'insert', pos: 5, val: 9 },
{ op: 'insert', pos: 9, val: 7 },
{ op: 'replace', pos: 11, val: 17 }
]); }
}
答案 4 :(得分：0)
这是一些Matlab代码，您的意见是否正确？似乎给出了正确的结果:)
clear all
s = char('democrat');
t = char('republican');
% Edit Matrix
m=length(s);
n=length(t);
mat=zeros(m+1,n+1);
for i=1:1:m
mat(i+1,1)=i;
end
for j=1:1:n
mat(1,j+1)=j;
end
for i=1:m
for j=1:n
if (s(i) == t(j))
mat(i+1,j+1)=mat(i,j);
else
mat(i+1,j+1)=1+min(min(mat(i+1,j),mat(i,j+1)),mat(i,j));
end
end
end
% Edit Sequence
s = char('democrat');
t = char('republican');
i = m+1;
j = n+1;
display([s ' --> ' t])
while(i ~= 1 && j ~= 1)
temp = min(min(mat(i-1,j-1), mat(i,j-1)), mat(i-1,j));
if(mat(i-1,j) == temp)
i = i - 1;
t = [t(1:j-1) s(i) t(j:end)];
disp(strcat(['iinsertion: i=' int2str(i) ' , j=' int2str(j) ' ; ' s ' --> ' t]))
elseif(mat(i-1,j-1) == temp)
if(mat(i-1,j-1) == mat(i,j))
i = i - 1;
j = j - 1;
disp(strcat(['uunchanged: i=' int2str(i) ' , j=' int2str(j) ' ; ' s ' --> ' t]))
else
i = i - 1;
j = j - 1;
t(j) = s(i);
disp(strcat(['substition: i=' int2str(i) ' , j=' int2str(j) ' ; ' s ' --> ' t]))
end
elseif(mat(i,j-1) == temp)
j = j - 1;
t(j) = [];
disp(strcat(['dddeletion: i=' int2str(i) ' , j=' int2str(j) ' ; ' s ' --> ' t]))
end
end
答案 5 :(得分：0)
JackIsJack的C＃实现回答了一些变化：
控制台应用程序代码：
class Program
{
static void Main(string[] args)
{
Levenshtein("1", "1234567890");
Levenshtein( "1234567890", "1");
Levenshtein("kitten", "mittens");
Levenshtein("mittens", "kitten");
Levenshtein("kitten", "sitting");
Levenshtein("sitting", "kitten");
Levenshtein("1234567890", "12356790");
Levenshtein("12356790", "1234567890");
Levenshtein("ceci est un test", "ceci n'est pas un test");
Levenshtein("ceci n'est pas un test", "ceci est un test");
}
static void Levenshtein(string string1, string string2)
{
Console.WriteLine("Levenstein '" + string1 + "' => '" + string2 + "'");
var string1_length = string1.Length;
var string2_length = string2.Length;
int[,] distance = new int[string1_length + 1, string2_length + 1];
for (int i = 0; i <= string1_length; i++)
{
distance[i, 0] = i;
}
for (int j = 0; j <= string2_length; j++)
{
distance[0, j] = j;
}
for (int i = 1; i <= string1_length; i++)
{
for (int j = 1; j <= string2_length; j++)
{
if (string1[i - 1] == string2[j - 1])
{
distance[i, j] = distance[i - 1, j - 1];
}
else
{
distance[i, j] = Math.Min(distance[i - 1, j] + 1, Math.Min(
distance[i, j - 1] + 1,
distance[i - 1, j - 1] + 1));
}
}
}
var LevenshteinDistance = distance[string1_length, string2_length];// for information only
Console.WriteLine($"Levernstein distance: {LevenshteinDistance}");
// List of operations
var current_posx = string1_length;
var current_posy = string2_length;
var stack = new Stack<string>(); // for outputting messages in forward direction
while (current_posx != 0 || current_posy != 0)
{
var cc = distance[current_posx, current_posy];
// edge cases
if (current_posy - 1 < 0)
{
stack.Push("Delete '" + string1[current_posx - 1] + "'");
current_posx--;
continue;
}
if (current_posx - 1 < 0)
{
stack.Push("Insert '" + string2[current_posy - 1] + "'");
current_posy--;
continue;
}
// Middle cases
var cc_L = distance[current_posx, current_posy - 1];
var cc_U = distance[current_posx - 1, current_posy];
var cc_D = distance[current_posx - 1, current_posy - 1];
if ((cc_D <= cc_L && cc_D <= cc_U) && (cc_D == cc - 1 || cc_D == cc))
{
if (cc_D == cc - 1)
{
stack.Push("Substitute '" + string1[current_posx - 1] + "' by '" + string2[current_posy - 1] + "'");
current_posx--;
current_posy--;
}
else
{
stack.Push("Keep '" + string1[current_posx - 1] + "'");
current_posx--;
current_posy--;
}
}
else if (cc_L <= cc_D && cc_L == cc - 1)
{
stack.Push("Insert '" + string2[current_posy - 1] + "'");
current_posy--;
}
else
{
stack.Push("Delete '" + string1[current_posx - 1]+"'");
current_posx--;
}
}
while(stack.Count > 0)
{
Console.WriteLine(stack.Pop());
}
}
}
答案 6 :(得分：0)
从python中实现的矩阵中推断出移动的回溯算法：
def _backtrack_string(matrix, output_word):
'''
Iteratively backtrack DP matrix to get optimal set of moves
Inputs: DP matrix (list:list:int),
Input word (str),
Output word (str),
Start x position in DP matrix (int),
Start y position in DP matrix (int)
Output: Optimal path (list)
'''
i = len(matrix) - 1
j = len(matrix[0]) - 1
optimal_path = []
while i > 0 and j > 0:
diagonal = matrix[i-1][j-1]
vertical = matrix[i-1][j]
horizontal = matrix[i][j-1]
current = matrix[i][j]
if diagonal <= vertical and diagonal <= horizontal and (diagonal <= current):
i = i - 1
j = j - 1
if diagonal == current - 1:
optimal_path.append("Replace " + str(j) + ", " + str(output_word[j]) )
elif horizontal <= vertical and horizontal <= current:
j = j - 1
optimal_path.append("Insert " + str(j) + ", " + str(output_word[j]))
elif vertical <= horizontal and vertical <= current:
i = i - 1
optimal_path.append("Delete " + str(i))
elif horizontal <= vertical and horizontal <= current:
j = j - 1
optimal_path.append("Insert " + str(j) + ", " + str(output_word[j]))
else:
i = i - 1
optimal_path.append("Delete " + str(i))
return reversed(optimal_path)
使用原始单词“ OPERATING”和所需单词“ CONSTANTINE”运行算法时得到的输出如下
Insert 0, C
Replace 2, N
Replace 3, S
Replace 4, T
Insert 6, N
Replace 10, E
"" C O N S T A N T I N E
"" [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11]
<-- Insert 0, C
O [1, 1, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
\ Replace 2, N
P [2, 2, 2, 2, 3, 4, 5, 6, 7, 8, 9, 10]
\ Replace 3, S
E [3, 3, 3, 3, 3, 4, 5, 6, 7, 8, 9, 9]
\ Replace 4, T
R [4, 4, 4, 4, 4, 4, 5, 6, 7, 8, 9, 10] No move
\ <-- Insert 6, N
A [5, 5, 5, 5, 5, 5, 4, 5, 6, 7, 8, 9]
\ No move
T [6, 6, 6, 6, 6, 5, 5, 5, 5, 6, 7, 8]
\ No move
I [7, 7, 7, 7, 7, 6, 6, 6, 6, 5, 6, 7]
\ No move
N [8, 8, 8, 7, 8, 7, 7, 6, 7, 6, 5, 6]
\ Replace 10, E
G [9, 9, 9, 8, 8, 8, 8, 7, 7, 7, 6, 6]
请注意，如果对角线上的元素与当前元素相同，则必须添加额外的条件。取决于垂直（上）和水平（左）位置中的值，可能会有删除或插入。当发生以下情况时，我们只会得到“无操作”或“替换”操作
# assume bottom right of a 2x2 matrix is the reference position
# and has value v
# the following is the situation where we get a replace operation
[v + 1 , v<]
[ v< , v]
# the following is the situation where we get a "no operation"
[v , v<]
[v<, v ]
我认为这是第一个答案中描述的算法可能会中断的地方。当两种操作都不正确时，上面的2x2矩阵中可能还有其他布置。输入“ OPERATING”和输出“ CONSTANTINE”显示的示例破坏了算法，除非将其考虑在内。