Algorithm 2 Weisfeiler–Lehman sampling [38]

Input:$G=\{V,E\}$

Parameters: batch size k, labeling budget $LB$, exploration budget $EB$

Initialization: test set T, labeled set $\mathcal{L}=\varnothing$, unlabeled set $\mathcal{U}=V\setminus T$

while $\left|\mathcal{U}\right|<LB$ do

$\mathcal{S}\leftarrow$ Pick k random seed nodes from $\mathcal{U}$

while $v\in \mathcal{S}$ do

$G_s\leftarrow$$EB$ hop neighborhood subgraph of v

$R\leftarrow$ Weisfeiler–Lehman $\left(Gs\right)$

$R\leftarrow R\cap \mathcal{U}$

$i\leftarrow argmaxR$, $n_i$ was labeled by oracles

$\mathcal{L}\leftarrow n_i\cup \mathcal{L}$, $\mathcal{U}\leftarrow \mathcal{U}\setminus n_i$

end while

end while