diagram make myself a code, want to use a variable instead of a file name, but an error, can't open, how do I solve, by the way how to optimize the path, I wrote the full path, are there any other writing? 
diagram make myself a code, want to use a variable instead of a file name, but an error, can't open, how do I solve, by the way how to optimize the path, I wrote the full path, are there any other writing?