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.

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

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.

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.