Here shows the data schema of one feature. There are several fields, including:

• _id:  the  index of the  feature, used in MongoDB

• cc:  the  value of Cyclomatic Complexity

• count:  the number of projects with this feature

• func_hash:  the MD5  Hash of the feature

• hv:  the value of Halstead Volume

• languages: the language used to write this function

• line_of_code: the value of line of the code

• location: an array, where each element is a key-value pair, the key is the name of the project that has this function, and the value is an array that contains the commit hash of the feature in the project.