Igor Thief with arbitrary axes

Nevermind, I answered my own question. Just digitize the data as if the axis was linear and then transform it afterwards. A Transform Axis then displays the data nicely. It would be nice if some other axis types (for instance those available in the Transform Axis dialog) were available in the Igor Thief procedure but it isn't really necessary. I'll show myself out.

John

Welcome to the forum. These are the best kinds of posts when you answer the question yourself. Was this a kind of rubber duck debugging, perhaps? :) I think square-root axes are rather uncommon, so I would not bet that support is added. Your approach was the best in this case. By the way, if your data happens to be continuous, I would like to recommend Tony's excellent Tracer package for the job (still, no sqrt axes):

https://www.wavemetrics.com/project/tracer

I second chozo's suggestion to use Tony's Tracer package for continuous data.  However, if your data points are discrete, there is an updated version of the Igor Thief that I wrote a while back, and I just added support for square root axes, as well as ln and reciprocal: https://www.wavemetrics.com/node/22225