CODEWITHSUNDEEP
torch
DavideChicco.it
DavideChicco.it

Reputation: 3470

Torch, which command to insert data in a Torch Tensor?

I'm using a Torch command to insert data into a simple table, and it works fine:

completeProfile = {};
table.foreach(firstHalf, function(i,v)table.insert(completeProfile,v) end);
table.foreach(secondHalf, function(i,v)table.insert(completeProfile,v) end);
table.foreach(presentWord, function(i,v) table.insert(completeProfile,v) end);

Now someone made me notice that using Torch Tensors would make everything more efficient. So I replaced the first line with 

completeProfile = torch.Tensor(CONSTANT_NUMBER);

but unfortunately I cannot find any Tensor function able to replace the table.insert() function.

Do you have any idea?

Upvotes: 0

Views: 5513

Answers (1)

ryanpattison
ryanpattison

Reputation: 6251

There is no function which corresponds to the append functionality of insert since Tensor objects are a fixed size. What I see your code doing is concatenating three tables into one. If you are using Tensors:

 firstHalf = torch.Tensor(firstHalf)
 secondHalf = torch.Tensor(secondHalf)
 presentWord = torch.Tensor(presentWord)

then concatenating them together is easy:

 completeProfile = firstHalf:cat(secondHalf):cat(presentWord)

Another option is to store the last index you inserted to so you know where to "append" onto the tensor. The function below creates a closure that will keep track of that last index for you. 

function appender(t)
   local last = 0
   return function(i, v)
       last = last + 1
       t[last] = v
   end
end

completeProfile = torch.Tensor(#firstHalf + #secondHalf + #presentWord)

profile_append = appender(completeProfile)

table.foreach(firstHalf, profile_append)
table.foreach(secondHalf, profile_append)
table.foreach(presentWord, profile_append)

Upvotes: 2

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