how to display a value in first column the second column number of times?

suppose i have a column vector x=[1 2 3 4]; and y=[2 3 3.5 4]

i want the output as xy=[1 1 2 2 2 3 3 3 3 4 4 4 4];

the number 3.5 can be rounded off to a whole number. here ive taken it as 4.

Answer 1

[Walter Roberson]

repelem(x, round(y))

[johnson saldanha]

Undefined function 'repelems' for input arguments of type 'double'.

Error in xx (line 50)

xy=repelems(x, round(y));

my version is 2013

[Walter Roberson]

Sorry, I had the name slightly wrong; I have fixed it.

However, R2013* did not have the function.

For your version, one of the possible approaches is

cell2mat(arrayfun(@(v, n) kron(v, ones(1,n)), x, round(y), 'uniform', 0))

and another approach is

cell2mat(arrayfun(@(v, n) v(ones(1,n)), x, round(y), 'uniform', 0))

[johnson saldanha]

Error using cat

Dimensions of matrices being concatenated are not consistent.

Error in cell2mat (line 84)

m{n} = cat(1,c{:,n});

Error in accelerationrate (line 51)

xy=cell2mat(arrayfun(@(v, n) kron(v, ones(1,n)), xy1(:,1), round(xy1(:,2)),

'uniform', 0))

im getting this error

[Walter Roberson]

Your question was asked for the case where y (number of repeats) is a row vector. Your code instead has xy1(:,2) as a column vector. What is your desired output in this case? Do you need output as rows of a cell vector of variable length? Should the output be as rows in which each input is repeated the appropriate number of times but the shorter rows are padded with nan?

You changed the input conditions so I have to assume you want a different output than you had asked about earlier.

If you continue to want a row vector of output, then use the code I indicated, passing in a row vector of y. As in

 xy=cell2mat(arrayfun(@(v, n) kron(v, ones(1,n)), xy1(:,1), round(xy1(:,2)).', 'uniform', 0));

Notice that the column vector has been transposed into a row vector, fitting the circumstance of the original question.

[johnson saldanha]

both the inputs are column vectors and i want the output as a column vector.

[Walter Roberson]

cell2mat(arrayfun(@(v, n) v(ones(n,1)), x, round(y), 'uniform', 0))   %assumes inputs are column vectors

[johnson saldanha]

i got the output. thank u