Pressing alt-c will apply any embedded filters (or URL filters) to Humdrum data in the text editor, and then replace the contents of the text editor with the filtered data.
Adding an empty spine
To add a new spine to Humdrum data, use the extract filter and the alt-c command. The following filter extracts all of the original spines, and adds a blank spine at the end of the data lines:
!!!filter: extract -s 1-$,0
The $ character symbolizes the last spine in the file, and 0 represents
a blank line.
Before the filter is compiled:
After pressing alt-c:
The filter line is now changed to !!!Xfilter: which indicates
that the filter has been applied (and will not be applied again).
This line can be deleted if no longer needed, or the X can be
deleted to re-apply the filter.
Transposing example
Here is an example of transposing Humdrum data:
Notice that the music is being displayed in E major, but the data is in C major. This is because the filter is applied to the Humdrum data in the text editor before it is converted into MEI data and then rendered into an SVG image.
In order to view the same data that generates the notation, press the alt-c command to compile the filter:
Now the musical data in the text data matches the graphical notation of the music.