# first¶

Returns true if first datapoint of a sequence, and false otherwise

This is true when the datapoint is first in a sequence. It is useful mainly for filtering:

where first or last


will return the first and last datapoint in your stream:

1,2,3,4,5

1,5


## Usage¶

This transform could be finding your wakeup time, based upon the first time you turn on your phone screen in the morning:

where dayhour > 4 | while(day == next:day, first) | t


The above transform removes the datapoints taken from midnight to 4am (to filter out long nights), and then returns the first datapoint of each day, finaally returning only the timestamp.

### Transform Details¶

Input SchemaOutput Schema
{}

{}