Transformations

Transform is the stage of the pipeline that decides whether a task derives values
or merely moves them. It runs after the task has read its data and before anything is
mapped to columns, so everything downstream (the filter, the mapping, the output), sees
whatever the transform produced.

The choices

Choice	What it does
None	Values pass straight through. Use this when you are copying data, not deriving it.
Python calculation	Compute derived values first; the results become available to the output.
R calculation	Marked coming later in the dialog. Not available yet.

The question to ask is which sentence describes the job. Copy these readings into that
table is None. Work out this figure from those readings is a calculation.

What a transform adds to the task

Choosing a calculation adds two tabs, and removing it takes them away again:

Tab	What it is for
Calculation	Write the script and declare the variables it produces
Calculation Preview	Check the values the script actually produced, before anything is written

Set Transform back to None and both disappear, because neither has anything to show.

The scalar / timeseries dataframe control on the Calculation tab is the task's mode,
not just the script's. When a task has a calculation, a Conditions
filter runs in that same mode rather than choosing its own.

What's Next

• Calculation: the Python script and its variables
• Calculation Preview: what the script produced
• Filters: the stage that runs next

Related

• Tasks: the whole pipeline this is one stage of
• Channels: the values a calculation reads
• Object properties: what a match's keys answer to