How can you create an empty table object with non-zero rows or non-zero columns?

Question

Anil 2014-1-15

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回答： Peter Perkins 2017-2-28

I am trying to initialise a table object of the correct dimension but not initialised with any data. This is possible with other native arrays, but I can't work out how to do it with a table.

Specifically, I'd like to be able to build a [0 x N] or [N x 0] table, so I can either add rows or columns one by one.

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Answer 1

Jacob Halbrooks 2014-1-15

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编辑：Jacob Halbrooks 2014-1-15

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You can use cell2table to initialize an empty table by providing a cell array of desired dimensions. For example, this initializes an empty table with 0 rows and 5 variables:

T = cell2table(cell(0,5));

Now you can add data by concatenation with another table. For example, this adds a row of data to the table created above:

T = [T ; cell2table({1,2,3,4,5})];

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Richard Allen 2017-2-23

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You should probably just use

T = table

Peter Perkins 2017-2-28

T = table is going to create a 0x0. That may be a good starting point, but strictly speaking it's not what the OP asked for.

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Answer 2

Peter Perkins 2017-2-28

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Really, the question is kind of ill-posed, because to create an empty table with a non-zero number of variables, you need to define what type each variable in a table is even if the table has zero rows.

>> array2table(zeros(0,5))
ans =
  0×5 empty table

creates an empty table with five variables, but all five are doubles, which may or may not be what you want. Ditto for cell2table(cell(0,5)). In general, you need to do something like

t = table(zeros(0,1),zeros(0,1,'single'),cell(0,1))

to define the data types.