List Operations


List Operations is an online app designed to perform set operations (intersection, subtraction and union) on data provided as two lists of items. It also offers a few supplemental functions (sorting, shuffling and duplicate items removal).


Before any operation is triggered, two lists of items have to be provided. The lists can be either directly pasted in the "List A" and "List B" input fields or read from files. If the source data are to be loaded from files, the files should be plain text files (no formatting) containing one item per each line. Next choose if the operations should be performed in a case-sensitive way or not. This choice affects results of all operations. For example, an union of lists containing the items "a" and "A", respectively will contain both "a" and "A" in the first case, but only "a" in the latter. If you are going to perform subtraction of a list, choose if in each step identical items should be removed all at once or only the first occurrence of a matching item. To get the intersection/overlap of the lists, click the A ∩ B button. To get the union of the lists, click the A + B button. Note that unlike mere pooling of the lists this operation will always provide a set of unique items (multiple occurrences of an item will be represented by a single occurrence in the union). Subtraction operations will be triggered with A - B and B - A button, respectively. Subtraction of list B from list A will remove matching items from list A. If there are more matching (identical) items in list A, the subtraction will either remove only the first item or all such items depending on the settings described previously.

The data in the Output field (both results of the app operations and data entered/pasted in the field by the user) can be further processed with a few additional functions. Clicking the Remove Duplicate Lines button will make the program search for multiple occurrences of the same item (data row) and remove all but the first one. The other functions - Sort, Reverse Order and Shuffle - will change the order of items in the Output field according to the function names.