can not coerce list with transactions with duplicated items :: Win7 SP1 64 :: R v3.02

apriori, duplicates, r, transactions, transformation

Solution

joran and DWin mentioned:

- Elements of character vectors in a_list are unique.

- There is a duplication in one of the vectors of b_list.

How it looks like. If I add the second "b" into the first vector of a_list2

> a_list2 <- list(
    c("a","b","b","c"),
    c("a","b"),
    c("a","b","d"),
    c("c","e"),
    c("c","e"),
    c("a","b","d","e")
)

in the following attempt to transform the data I get the error

> a_trans2 <- as(a_list2,"transaction")
Error in as(a_list2, "transaction") : 
   no method or default for coercing “list” to “transaction”

It appears that b_list has "Steady Whitening Toothpast" mentioned twice in the fourth vector. Manual removal of this duplication solved the issue.

> b_trans2 <- as(b_list2,"transactions")
> summary(b_trans2)
transactions as itemMatrix in sparse format with
6 rows (elements/itemsets/transactions) and
... and so on ...
2    Best Choice Mini Donuts
3           Better Beef Soup

Speaking about the solution for the real data processing, the following code delivers no errors.

aggrData <- split(selData$product_name,selData$transaction_id)

listData <- list()
for (i in 1:length(aggrData)) {
    listData[[i]] <- as.character(aggrData[[i]][!duplicated(aggrData[[i]])])
}

trnsData <- as(listData,"transactions")

Though, the following line nor attempts with other parameters deliver no rules.

> rules <- apriori(trnsData)

parameter specification:
... and so on ...
writing ... [0 rule(s)] done [0.00s].
creating S4 object  ... done [0.00s].

Yet this is a totally different story.

Problem

Problem I can not understand how to transform list to transactions for further processing by apriori algorithm. I have a synthetic example that works, and real (well, a subset of Foodmart database) that does not work; they look the same to me on the systems level. Please help me to transform a list to transactions object. System setup ``` > version platform x86_64-w64-mingw32 arch x86_64 os mingw32 system x86_64, mingw32 status major 3 minor 0.2 year 2013 month 09 day 25 svn rev 63987 language R version.string R version 3.0.2 (2013-09-25) nickname Frisbee Sailing ``` Code to replicate Code that works ``` > a_list <- list( c("a","b","c"), c("a","b"), c("a","b","d"), c("c","e"), c("c","e"), c("a","b","d","e") ) > a_trans <- as(a_list,"transactions") > summary(a_trans) transactions as itemMatrix in sparse format with 6 rows (elements/itemsets/transactions) and 5 columns (items) and a density of 0.5333333 ... and so on ... 2 b 3 c > a_rules <- apriori(a_trans) parameter specification: confidence minval smax arem aval originalSupport support minlen maxlen target ext ... and so on ... writing ... [17 rule(s)] done [0.00s]. creating S4 object ... done [0.00s]. ``` Code that does not work ``` > b_list <- list( c("PigTail Frozen Pepperoni Pizza","Bird Call Childrens Cold Remedy","Steady Silky Smooth Hair Conditioner","CDR Regular Coffee"), c("Horatio Graham Crackers","Excellent Apple Drink","Blue Medal Small Eggs","Cormorant Copper Cleaner","High Quality Copper Cleaner","Fast Apple Fruit Roll"), c("Toucan Canned Mixed Fruit","Landslide Salt","Gorilla Sour Cream","Hermanos Firm Tofu"), c("Swell Canned Mixed Fruit","Washington Diet Soda","Super Apple Jam","Plato Strawberry Preserves","Steady Whitening Toothpast","Steady Whitening Toothpast","Better Beef Soup","Hermanos Squash","Carrington Frozen Cheese Pizza","Fort West Fondue Mix","Best Choice Mini Donuts","Cormorant Copper Pot Scrubber","Ebony Cantelope","Denny D-Size Batteries","Akron Eyeglass Screwdriver"), c("Big Time Ice Cream Sandwich","Musial Mints","Portsmouth Imported Beer","CDR Vegetable Oil","Just Right Rice Soup","Carrington Frozen Peas","High Quality 100 Watt Lightbulb","Fort West Dried Dates"), c("Consolidated Tartar Control Toothpaste","Plato Tomato Sauce","Quick Seasoned Hamburger") ) > b_trans <- as(b_list,"transactions") Error in asMethod(object) : can not coerce list with transactions with duplicated items > summary(b_trans) Error in summary(b_trans) : error in evaluating the argument 'object' in selecting a method for function 'summary': Error: object 'b_trans' not found ``` Funny thing ``` > duplicated(a_list) [1] FALSE FALSE FALSE FALSE TRUE FALSE > duplicated(b_list) [1] FALSE FALSE FALSE FALSE FALSE FALSE ``` Any ideas why this fabulous (WTF) thing happens?

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