Before version 1.13 (released in April 2017), you could only provide one input file, and the flag used to provide it depended on its type (CSV, GPX, ESRI Shapefile, etc). Commands looked like this:
heatmap.py -o map.png --width 100 --points plainfile
heatmap.py -o map.png --width 100 --csv points.csv
heatmap.py -o map.png --width 100 --gpx track.gpx
heatmap.py -o map.png --width 100 --shp_file points.shp
As of version 1.13, the equivalent of those four commands would look like this:
heatmap.py -o map.png --width 100 plainfile
heatmap.py -o map.png --width 100 points.csv
heatmap.py -o map.png --width 100 track.gpx
heatmap.py -o map.png --width 100 points.shp
Moreover, you can now specify multiple input files, and they need not be the same type.
heatmap.py -o map.png --width 100 track*.gpx extras.csv morepoints.shp
The type of the input file is guessed from the filename extension
(defaulting to the original plain type), but if your files are
named oddly and you need to override the type, you can do that with
--filetype.
heatmap.py -o map.png --width 100 --filetype gpx *.xml