How to makeCallGraph() without having a package?

[telenskyt]

Hello,

I have an extensive code with many *.R files containing many functions. I don't have a package yet (too early in the development, it has yet to be determined, what parts of code would constitute what package(s) ...). I want to make a function call graph. I checked the makeCallGraph function of this package, but according to the documentation, it seems it takes package as the input - the obj parameter - citing the help:

obj | The name of one or more packages as a string, optionally prefixed with "package:". This can be a vector of package names. Currently the packages should already be on the search path. Other inputs may be supported in the future

Supplying file name results in an error. I also tried to provide a function as the obj, but it creates no edges.

PS: my goal is to make a call graph from multiple source files, while distinguishing in the graph which source file the function belongs to. Please let me know how to do this.