data pivot - calculated columns

[shapiromatron]

Enable the ability to add calculated fields in a data pivot whose output is derived from other fields in the dataset. Coupled with #987, this allows for users to mix and match columns to present to the right of a data pivot using information presented in the visual.

For example:

• The endpoints column: ${endpoint name} (${response units}) @ ${observation time text}
• The dose column: match(dose,0)?-:${dose} ${dose units}
• The response column: ${response} ± round(stdev,2) (round(percent control mean,1)%)

Renders:

[rabstejnek]

@shapiromatron Ready for review!

• You can include a column value by doing ${column}
  • ie This is a ${species}. with {species: "rat"} returns This is a rat.
• You can use ternaries by doing match(column,str/int)?Truthy string:Falsey string
  • ie match(species,"cat")?This is a cat.:This is not a cat. with {species: "rat"} returns This is not a cat.
• You can escape characters using \
  • ie \${species} would return ${species}

[rabstejnek]

@shapiromatron I have updated the parser language so that it can handle nested ternaries correctly; an example is in the test suite. I also added the exists condition with some tests. The logic for exists is as follows:

return options.getValue(id) != null & options.getValue(id) != "";

There is also an npm script that generates the query and format parsers:

npm run generate-parsers

This PR is ready for review!

[shapiromatron]

@rabstejnek I think you have to do the final review b/c I opened the PR initially, but I think this is great and will be a I think a highlight of our next release.

I made the following edits:

• 782feb4 fix docs (facepalm) (17 seconds ago) {Andy Shapiro}
• 19433ec add some text to describe how to use (50 minutes ago) {Andy Shapiro}
• b3d9072 fix test case (80 minutes ago) {Andy Shapiro}
• 3be80db add round (2 hours ago) {Andy Shapiro}
• 99aef96 add "to_right" to fixture; should have added in data pivot - add columns to the right of the figure #987 (3 hours ago) {Andy Shapiro}
• 9d17e63 use latest peggy version (6 hours ago) {Andy Shapiro}
• 11883b8 fix migration conflict (6 hours ago) {Andy Shapiro}

If you're ok w/ the changes, please approve.

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To document our sidebar chats, but it'd be good to get this in use initially to determine the need first:

• we may change ${} to show() in the future
• we may rewrite the ternary expression a?b:c to ifelse(a,b,c)