Fig. 2
From: Dimension independent data sets approximation and applications to classification
Level lines of the signal \(u_{\mathbb {D}_{m,j}}\) for \(m=32\), \(j=1,2,3\), and \(\alpha =0,1,1,2\). Depicted are the data set (blue dots correspond to the value 1 while magenta dots to the value 0) and three level lines corresponding to levels at 20%, 50%, and 80% of the signal’s maximal value, respectively. Darker lines correspond to higher levels. The parameter \(\alpha \) grows from left to right. The boundary of the set \(S_j\) appears as a dashed black line