Sensor array discriminative abilities demonstration with dimensionality reduction algorithms in dry (top row) and humid (bottom row) air. (a,d) Principal Components Analysis (PCA). (b,e) Local Linear Embedding (LLE). (c,f) Linear Discriminant Analysis (LDA). Dot size corresponds to the concentration (not in scale; NH3 and H2S are presented at 100, 200, 500, 800, 1000, 1500 ppb, NO2 at 100, 200, 500, 800, 1000 ppb and Et-SH at 40, 80, 120, 160, 200 ppb concentrations). Dotted color ellipses include all the measurements related to a specific gas and border regions on the diagram.