# segment

Syntax

segment(X, [segmentOffset=true])

Arguments

X is a vector.

segmentOffset segmentOffset is a Boolean value. The default value is true.

Details

divide a vector into groups. Each group is composed of identical values next to each other. For example, [1,1,2,2,1,1,1] is divided into 3 groups: [1,1], [2,2] and [1,1,1].

Return a vector of the same length as X.

• If segmentOffset=true, each element of the result is the index(in X) of the first element in each group.

• If segmentOffset=false, each element of the result is its group number. Group numbers start from 0.

Examples

Ex 1.

```\$ x = 1 1 2 4 4 5 2 5 NULL NULL
\$ segment(x);
[0,0,2,3,3,5,6,7,8,8]

\$ segment(x, false);
[0,0,1,2,2,3,4,5,6,6]
```

Ex 2.

```\$ x = 1 2 1 2 1 2 1 2 1 2 1 2;
\$ y = 0 0 1 1 1 2 2 1 1 3 3 2;
\$ t = table(x,y);
\$ select *, cumsum(x) from t context by segment(y);
```

y

x

cumsum_x

0

1

1

0

2

3

1

1

1

1

2

3

1

1

4

2

2

2

2

1

3

1

2

2

1

1

3

3

2

2

3

1

3

2

2

2