Algorithm 3. The pseudo-code of EGFA for feature selection (EGFAFS).

1. Input: The size of the recommended feature pool $q$, the size of dust population $n$, the size of the features found by EGFAFS $c$, the No. of Random Forests (RF) $num$, the No. of iterations $T_{\max }$

2. Construct a recommended feature pool by RFs based on the Gini index

3. Initialize the dust population of size $n$ by Equation (9), calculate the mass of each particle by Equation (10)

4. while $t<T_{\max }$ do

5.   Move the surrounding dust particles toward their center as Figure 3

6.   Some surrounding dust particles are absorbed by their center

7.   Explosion strategy produces some dust particles as Figure 4

8.   $t=t+1$

9. End while

10. Return the optimal subset of features