# changed¶

Returns true if the datapoint has a different value from the previous one

The changed transform returns true if the current datapoint’s data is different from the previous datapoint.

Given the following data:

[1, 2, 3, 3, 4]


running the changed transform on it will result in:

(true, true, true, false, true)


## Usage¶

The changed transform is useful whenever you don’t care about the specific datapoints, but when they change with respect to a certain metric.

Suppose you have a stream of activities gathered by a phone:

["walking", "walking", "still", "still", "still", "walking", "walking"]


You usually care about the transitions between activities:

if changed


gives:

["walking", "still", "running"]


Remember that each datapoint comes with a timestamp, so the length of each activity can be extracted by looking at the timestamp differences.

### Transform Details¶

Input SchemaOutput Schema
{}

{
"type": "boolean"
}