Initial part of apriori

Currently only gets frequency count for first candidate set.

a3.r

 # Clear console.
-cat("\014")  
+cat('\014')
+
+
+###
+ # The "cat" function seems to be an all around better alternative to "print".
+ # ("print" has a tendency to add extra, frivilous output that makes it look dirty and difficult to read.)
+ #
+ # This wrapper for "cat" then automatically adds a newline to the end of the message, effectively accomplishing
+ # what you would intuitively expect "print" to do.
+ #
+ # See references.md file for source of idea.
+ ##
+catn <- function(message, trailing='\n') {
+    cat(message)
+    cat(trailing)
+}
+
+
+###
+ #
+ ##
+apriori <- function(itemsets, display_candidates=TRUE, display_frequent=FALSE) {
+    # Initialize variables.
+    level = 1
+    candidate_itemsets = list(itemsets, NULL)
+    frequent_itemsets = list(itemsets, NULL)
+
+    # Loop until no more frequent itemsets are found for current level.
+    while (! is.null(frequent_itemsets[[level]])) {
+        level = level + 1
+
+        candidate_itemsets[[level]] = apriori_gen_candidates(frequent_itemsets[[level - 1]], level)
+    }
+
+    # Optionally display candidate itemsets.
+    if (display_candidates) {
+        catn('')
+        catn('Candidate Itemsets')
+        print(candidate_itemsets)
+    }
+
+    # Optionally display known frequent itemsets.
+    if (display_frequent) {
+        catn('')
+        catn('Frequent Itemsets')
+        print(frequent_itemsets)
+    }
+}
+
+
+###
+ # Generate all possible candidate itemsets.
+ ##
+apriori_gen_candidates <- function(prev_freq_sets, level) {
+    candidates <- NULL
+    cand_names <- NULL
+
+    # Loop through our previous frequent sets.
+    for (prev_freq_set in prev_freq_sets) {
+        catn('')
+        catn('================================================================================')
+        catn(paste('Itemset: (', paste(prev_freq_set, collapse=', '), ')'))
+
+        # Loop through each item in frequent sets.
+        for (item_index in 1:length(prev_freq_set)) {
+
+            catn('')
+            catn('====================')
+            item <- prev_freq_set[item_index]
+            catn(paste('New Item from Set:', item))
+
+            # Update item frequency in candidates dictionary.
+            if (is.null(candidates)) {
+                # Candidates dict does not yet exist. Initialize.
+                candidates <- c(1)
+                cand_names <- c(item)
+                names(candidates) <- c(cand_names)
+
+            } else {
+                # Candidates dict exists. Update accordingly.
+                if (is.element(item, cand_names)) {
+                    # Item in list. Increment counter.
+                    catn('Not Null')
+                    candidates[item] <- candidates[item] + 1
+                } else {
+                    # Item not yet in list. Add.
+                    catn('Null')
+                    candidates <- c(candidates, 1)
+                    cand_names <- c(cand_names, item)
+                    names(candidates) <- cand_names
+                }
+                print(candidates)
+            }
+
+            catn('====================')
+        }
+
+        catn('')
+        catn('================================================================================')
+        catn('')
+    }
+
+    # Return found candidates.
+    return(candidates)
+}
+
+
+###
+ #
+ ##
+apriori_check_subsets <- function() {
+
+}
+
 
 # Create itemset.
 itemsets <- list(c(1, 2, 3), c(1, 2, 4), c(1, 2, 5), c(1, 3, 4), c(1, 3, 5), c(2, 3, 4), c(2, 3, 5), c(3, 4, 5))
+
+# Run apriori.
+apriori(itemsets)

documents/references.md

@@ -16,3 +16,7 @@ All references to external logic. Includes anything from stack overflow links to
 ### Run R Script in Terminal
 Because RStudio seems like a pretty bad IDE. Surprisingly, Terminal + Sublime Text is better.
 <https://support.rstudio.com/hc/en-us/articles/218012917-How-to-run-R-scripts-from-the-command-line>
+
+### Alternative to the "Print" Function
+Because it doesn't always behave how I expect, and tends to give additional, "dirty" output that I don't want.
+<https://stackoverflow.com/questions/11230957/alternative-to-print-and-cat>