The alt-c command compiles embedded filters.

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:

view before compiling a filter.
Humdrum data before compiling a filter.

After pressing alt-c:

view after compiling a filter.
Humdrum data after compiling a filter.

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:

view before compiling a transpose filter.
Humdrum data before compiling a transpose filter.

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:

view after compiling a transpose filter.
Humdrum data after compiling a transpose filter.

Now the musical data in the text data matches the graphical notation of the music.