Algorithm 2: Feature Extraction

Input:  A{a1, a2…an}, a set of activity

SIA, a tuple of sensor importance

w, threshold

Output:Ar{a1,a2…an}, activities after feature extraction

1. Ar←Ø;

2. for each a in A:

3.    ns←Ø;//new sensor sequence

4.    for each s in a.sq:

5.       temp←getvalue(SIA,sq.s1,s)//Get the importance of s

6.       if temp > w and s does not repeat:

7.          ns←◡s

8.       end if

9.    end for

10.   Ar←◡{a.bt,a.et,ns}

11. end for

12. return Ar