slice

Syntax

slice(obj, index)

or

slice(obj, rowIndex, [colIndex])

which is equivalent to

obj[index] or obj[rowIndex, colIndex]

Arguments

obj can be an array vector, a matrix or a table.

index, rowIndex and colIndex can be scalar/vector/pair indicating the row or column index. If index, rowIndex or colIndex is a pair, it indicates the range of index which is left-closed and right-open.

Details

For slice(obj, index):

• If obj is an array vector and

  • index is a scalar, it returns a vector indicating a column;

  • index is a vector, it returns an array vector of selected rows;

  • index is a pair, it returns an array vector of selected columns.

• If obj is a matrix and

  • index is a scalar, it returns a vector indicating a column.

  • index is a vector or a pair, it returns a matrix of selected columns.

• If obj is a table and

  • index is a scalar, it returns a dictionary indicating a row.

  • index is a vector or a pair, it returns a table of selected rows.

For slice(obj, rowIndex, [colIndex]):

• If obj is an array vector and

  • rowIndex and colIndex are both scalars, it returns a vector indicating a column;

  • rowIndex is a scalar and colIndex is a pair (or vise versa), it returns an array vector of selected rows and columns;

  • rowIndex and colIndex are both pair, it returns an array vector of selected rows and columns.

• If obj is a matrix and

  • rowIndex and colIndex are both scalars, it returns a scalar indicating the value of specified element of the matrix.

  • rowIndex is a scalar and colIndex is a pair (or vise versa), it returns a submatrix of selected rows and columns.

  • rowIndex and colIndex are both vectors or pairs, it returns a submatrix of selected rows and columns.

• If obj is a table and

  • rowIndex and colIndex are both scalars, return a scalar indicating the value of specified element of the table.

  • rowIndex is a scalar and colIndex is a pair (or vise versa), it returns a table of selected rows and columns.

  • rowIndex and colIndex are both vectors or pairs, it returns a table of selected rows and columns.

Note:

• To get a particular row or column from a table, consider using function col or row.

• When index, rowIndex or colIndex specifies the index range of an array vector or matrix, if the values are not within [0, size(X)-1], the corresponding results are NULL values.

Examples

If obj is a matrix:

$ m=1..9$3:3
m.slice(0);
[1,2,3]

$ m.slice([0]);

#0
1
2
3

$ m.slice(0:2);

#0	#1
1	4
2	5
3	6

$ m.slice(0 2);

#0	#1
1	7
2	8
3	9

$ m.slice(0,1);
4

$ m.slice(0 1,0 1);

#0	#1
1	4
2	5

$ m.slice(1:2,1:2);

#0
5

If obj is a table:

$ t=table(`A`B`C as sym,2018.01.01..2018.01.03 as date,10 48 5 as val)
t.slice(0);
val->10
date->2018.01.01
sym->A
t.slice([0]);

sym	date	val
A	2018.01.01	10

$ t.slice(0 1);

sym	date	val
A	2018.01.01	10
B	2018.01.02	48

$ t.slice(0:1);

sym	date	val
A	2018.01.01	10

$ t.slice(0,1);
2018.01.01

$ t.slice(0 1,0 1);

sym	date
A	2018.01.01
B	2018.01.02

$ t.slice(1:2,1:2);

date
2018.01.02

If obj is an array vector:

$ av =array(DOUBLE[], 0, 10).append!([1.0, 2.1 4.1 6.8, 0.5 2.2 2]);
$ av[1]
[,4.1,2.2]
$ av[1,1]
[4.1]
$ av[1:3,1:3]
[[4.1,6.8],[2.2,2]]