get a subcell from a bigger cell

I have a cell of 10x9 named 'a', each index contains a string. How can i create a sub cell if i have two vectors (f,c) with the indexes that i want. e.g. imagine a 2x3 cell a and indexes f and c

 a={('this'), ('is') ,('big');('he') ,('buys') ,('it')}
 f=[1,1,2];
 c=[1,2,3];

the result i want is b={('this'), ('is');('it'),('')}

[Jan]

There are no parentheses around the strings:

a = {'this', 'is', 'big'; 'he', 'buys', 'it'}

Now please explain, why for [1,1,2] the cell {'this', 'is'} is created. What is the relation between the indices and the output? Of course we could try to guess this, but it is more efficient, if you explain it.

[Miguel Reina]

the indexes are found following a 2x3 matrix said

 b=[1 1 0;0 0 1]

in which 1 indicates the "correct" words following a criteria. so to find the indexes of those words i used

 [c,f]=find(b==1);

[Jan]

Wouldn't it be easier to apply directly:

a(b)

Answer 1

[Guillaume]

Use ind2sub:

a(ind2sub(size(a), f, c))

The result will be 1x3 vector not an arbitrary sized array.