# Need to create lists out each row of a matrix
**URL:** https://forum.kx.com/t/need-to-create-lists-out-each-row-of-a-matrix/10924
**Category:** Community Support
**Tags:** kdb-and-q
**Created:** [March 31, 2016, 12:35pm UTC](https://forum.kx.com/t/need-to-create-lists-out-each-row-of-a-matrix/10924 "2016-03-31T12:35:00Z")
**Posts on this page:** 6
**Page:** 1
### Author:  [@Krishna1](https://forum.kx.com/u/Krishna1)
#### Post date: [March 31, 2016, 12:35pm UTC](https://forum.kx.com/t/need-to-create-lists-out-each-row-of-a-matrix/10924/1 "2016-03-31T12:35:00Z")
Hello,
How may I create a list of lists, each inner list being a row of a matrix?
eg:
matrix :
1 2
2 3
4 5
4 6
result-\>
((1;2);(2;3);(4;5);(4;6))
Thanks,
Kumar
---
### Author:  [@thomas\_smyth](https://forum.kx.com/u/thomas_smyth)
#### Post date: [March 31, 2016, 12:49pm UTC](https://forum.kx.com/t/need-to-create-lists-out-each-row-of-a-matrix/10924/2 "2016-03-31T12:49:00Z")
Hi Krishna,
Not exactly sure what you mean here, the example you have given is a list of lists (i.e. a matrix):
q)((1;2);(2;3);(4;5);(4;6))
1 2
2 3
4 5
4 6
If you wish to create a list of lists/matrix from a single list consider using # with the dimensions of the matrix:
q)(4 2)#til 8
0 1
2 3
4 5
6 7
For an unknown length you may use:
q)(0N 2)#til 8
0 1
2 3
4 5
6 7
Which gives an equivalent result to using cut:
q)2 cut til 8
0 1
2 3
4 5
6 7
Regards,
Thomas Smyth
AquaQ Analytics
---
### Author:  [@Krishna1](https://forum.kx.com/u/Krishna1)
#### Post date: [March 31, 2016, 1:04pm UTC](https://forum.kx.com/t/need-to-create-lists-out-each-row-of-a-matrix/10924/3 "2016-03-31T13:04:00Z")
Thanks, Thomas.
Let me clarify:
I want to treat a row of a matrix as an index into another matrix.
q) a:((1;2);(2;3);(4;5);(4;6))
q) b:6 6 # til 36(for example)
I want to use each element of ‘a’ as a (row;column) pair.
In my case, when I do b[a[0]], I get
6 7 8 9 10 11
12 13 14 15 16 17,
when , actually I want b[1;2] -\> 8.
Regards,
Krishna
---
### Author:  [@Krishna1](https://forum.kx.com/u/Krishna1)
#### Post date: [March 31, 2016, 1:20pm UTC](https://forum.kx.com/t/need-to-create-lists-out-each-row-of-a-matrix/10924/4 "2016-03-31T13:20:00Z")
Little roundabout code:
a:((1;2);(2;3);(3;5);(4;6)) -\> matrix containing indices (row;col) pairs.
rows:500
cols: 10
z:(rows\*cols) # 0;
z[(cols\*a[;0])+a[;1]]:1; -\>
z:(rows,cols]#z;
My two pence.
Kumar
---
### Author:  [@thomas\_smyth](https://forum.kx.com/u/thomas_smyth)
#### Post date: [March 31, 2016, 1:39pm UTC](https://forum.kx.com/t/need-to-create-lists-out-each-row-of-a-matrix/10924/5 "2016-03-31T13:39:00Z")
Hi,
You could use either of the following:
q)b ./: a
8 15 29 0N
q).[b;] each a
8 15 29 0N
Regards,
Thomas Smyth
AquaQ Analytics
---
### Author:  [@Krishna1](https://forum.kx.com/u/Krishna1)
#### Post date: [March 31, 2016, 1:55pm UTC](https://forum.kx.com/t/need-to-create-lists-out-each-row-of-a-matrix/10924/6 "2016-03-31T13:55:00Z")
Much appreciated, Thomas.
Regards,
Kumar