# Channel

## class nominal.Channel

A write address for one named series on a stream.

A channel is a named series within a dataset, roughly a column. This
object is where points for it are written: a stream, a name, and the
tags to stamp on each point. Creating one sends nothing to Nominal.
The channel appears in Nominal when the first point arrives.

```matlab
ch = s.channel("rpm");
ch.tag("bank", "1");
ch.push(timestamps, values);
```

Tags belong to points, not to the channel. Earlier points keep the tags
they were sent with, later ones carry the new set, and all land in the
same channel. Keep tag cardinality low: anything that changes every
point belongs in its own channel.

For several channels sharing one clock, nominal.Stream.push is faster.

> **See also**
>
> [`nominal.Stream`](https://dev.nominal.io/matlab/ref/Stream.md#nominal.Stream "nominal.Stream")

Constructor Summary

Property Summary
:   ### Name

    Channel name this address writes under.

Method Summary
:   ### tag(key, value)

    Stamp a key-value pair on every point written from here on.

    ### push(timestamps, values)

    Write a batch of samples to this channel.

    ```matlab
    ch.push(t, v)
    ```

    Blocks if the stream has saturated.

    Parameters:
    :   - **timestamps**

          int64 nanoseconds or a datetime vector.
          Literal, including zero.
        - **values**

          Double vector of the same length.