||This part of algorithm is implemented by InitFrontWithOneMemember() procedure. This procedure erases data from large sets repository called frequentedSets and auxiliary repository called candidateSets. It also deletes data from tree structure at treeForm.treeControl1 by calling roots.Clear() method variable roots represents roots of graph structure and is obtained by calling of treeForm.treeControl1.getRootNodes() .
Also structure which holds information about chart on chartForm screen is cleaned by calling chartForm.myBarChart.Reset().
Then frequentedSets are filled with large single-member sets. Each single-member set represents one column from database table selected by Load data action. Algorithm counts number of occureneces of value 1 in table for each column. This is established by creating an SQL query and hitting it against database. Then divides number of occurence by count of all rows. If result is >= defined minimal support, set which corresponds to this item is said to be large and inserted to the frequentedSets repository. If user checked flag "Show all nodes"(twhich corresponds to variable ShowAllNodes) the sets which are considered small are inserted to the tree structure on treeForm and consequently displayed. All single-member sets are inserted to chartForm.