It appears that the flow variable tab in the Maths Formula node is not working correctly for the "Append Column" section. Therefore there appears no way to set what the new column will be called in the Maths formula node using Flow variables.
I am not sure what you mean... Did you set the parameter "replaced_column" to a string-valued flow variable? I just tried it and it worked. (KNIME 2.7.x, x64, Win7)
The append_column parameter just to switch between replace and append. When this parameter is true, it will append, else replace. (You cannot set this parameter, because it is a boolean valued parameter and no flow variable with type boolean is possible.)
HTH. Cheers, gabor
It is not the Replace Column part I want to alter. It is the Append Column part of the dialog, i.e. I want to add a new column with a new name set by a flow variable. This doesnt seem to be possible, as the Append Column dialog box in the config display is not conveyed properly in the flow variables tab.
I think I did understand your requirements, but apologize if I misunderstood. Maybe I was not explaining properly. I think you do want to change the replace_column value. Set the radiobox to the new column and the value on the flow variable tab assigned to the replace_column parameter will work as if it were the new column's name. (Please check the attached workflow.)
I think this was historically created that way. It might be confusing, but this is an advanced topic, so I guess the compatibility with the older version had higher priority than to recreate it with a more meaningful name (like simply "column"). It would be nice if the node description would allow to specify (and show in an expert mode, or as a tool tip) how you can set the value in the flow variables tab.
Thanks for sticking with me, you are quite right. The replaced_column variable in the node is used to affect both the "Append Column" box and the "Replaced Column" box in the node config. The wording here is certainly confusing, as I have found out, but at least I can do what I need now.
Many thanks for the info.
Maybe it would be useful if the actual value of the parameters were available as a prompt/watermark or something similar (gray text disappearing when edited) in the custom values. That way, playing with the settings on other tabs would help find out these details.
I am glad you could solve your problem.