Figure 2. Heat maps of metabolites by habitual smoking groups. (A) Heat maps display smoking-related metabolites by habitual smoking groups (current cigarette smokers [CS], past smokers [PS], and never smokers [NS]) at the baseline survey, separate for each sex. Hierarchical clustering was applied to group both metabolites and individuals using Ward’s methods and Euclidean distance. (B) Heat map illustrates smoking-related metabolites by habitual smoking groups (cigarette smokers, HTP users, past smokers, and never smokers) during the follow-up survey. Similar to the previous analysis, hierarchical clustering was employed for grouping metabolites and participants using Ward’s methods and Euclidean distance.
