generate random DNA sequence

I would like to randomly generate a set of 7-bases DNA sequences with a weighted probability. I want to have 20 sequences.

I code it as

for i=20
R_1{i}= randsample('ACGT',1,true,[1 0 0 0]);
R_2{i}= randsample('ACGT',1,true,[0.5 0 0.5 0]);
R_3{i}= randsample('ACGT',1,true,[0.25 0.25 0.25 0.25]);
R_4{i}= randsample('ACGT',1,true,[0.5 0 0 0.5]);
R_5{i}= randsample('ACGT',1,true,[0 0 0 1]);
R_6{i}= randsample('ACGT',1,true,[0.5 0 0 0.5]);
R_7{i}= randsample('ACGT',1,true,[0.5 0 0.5 0]);
end

But, it turns out that each cell has no string.

How can I code it correctly? In addition, how can I concatenate them into a single string as a DNA sequence?

Answer 1

[Walter Roberson]

You wrote

for i=20

which should have been

for i = 1 : 20