Let's look at the prerequisites to preprocess MIDI files:

1. Download the MIDI song repository:

https://github.com/dshieble/Music_RBM/tree/master/Pop_Music_Midi

2. Download the Python codes to manipulate MIDI songs:

https://github.com/dshieble/Music_RBM/blob/master/midi_manipulation.py

3. Install the "reticulate" package, which provides the R interface to Python:

Install.packages("reticulate") 

4. Import Python libraries:

use_condaenv("python27") 
midi <- import_from_path("midi",path="C:/ProgramData/Anaconda2/Lib/site-packages") 
np <- import("numpy") 
msgpack <- import_from_path("msgpack",path="C:/ProgramData/Anaconda2/Lib/site-packages") 
psys <- import("sys") 
tqdm <- import_from_path("tqdm",path="C:/ProgramData/Anaconda2/Lib/site-packages") 
midi_manipulation_updated <- import_from_path("midi_manipulation_updated",path="C:/Music_RBM") 
glob <- import("glob")