I've been trying to use cSPADE on a dataset I have with ~7million records in my transactions file (7 million unique sequenceID x eventID pairs). The support results I get when I try to run cSPADE on this dataset seem completely wrong. However, when I use ~86,000 records (the head of the previous file, more or less), the results look right. I've noticed that till this point the verbose log prints out that only 1 partition is used, while when I try ~850,000 records, 3 partitions are used.
Verbose output when using 100,000 records (with reasonable looking results):
> s1 <- cspade(trans, parameter = list(support = 0.1,maxlen=1), control = list(verbose = TRUE))
parameter specification:
support : 0.1
maxsize : 10
maxlen : 1
algorithmic control:
bfstype : FALSE
verbose : TRUE
summary : FALSE
tidLists : FALSE
preprocessing ... 1 partition(s), 1.98 MB [0.7s]
mining transactions ... 0 MB [0.21s]
reading sequences ... [0.03s]
total elapsed time: 0.94s
> summary(s1)
set of 14 sequences with
most frequent items:
A B C D E (Other)
2 2 1 1 1 8
.
.
.
summary of quality measures:
support
Min. :0.1306
1st Qu.:0.3701
Median :0.7021
Mean :0.5773
3rd Qu.:0.7184
Max. :0.9903
includes transaction ID lists: FALSE
mining info:
data ntransactions nsequences support
trans 83686 10059 0.1
Verbose output when using 1000,000 records (with wrong looking results):
> s1 <- cspade(trans, parameter = list(support = 0.1,maxlen=1), control =
list(verbose = TRUE))
parameter specification:
support : 0.1
maxsize : 10
maxlen : 1
algorithmic control:
bfstype : FALSE
verbose : TRUE
summary : FALSE
tidLists : FALSE
preprocessing ... 3 partition(s), 19.55 MB [4.6s]
mining transactions ... 0 MB [0.6s]
reading sequences ... [0.01s]
total elapsed time: 5.19s
> summary(s1)
set of 0 sequences with
most frequent items:
integer(0)
most frequent elements:
integer(0)
element (sequence) size distribution:
< table of extent 0 >
sequence length distribution:
< table of extent 0 >
summary of quality measures:
< table of extent 0 >
includes transaction ID lists: FALSE
mining info:
data ntransactions nsequences support
trans 826830 96238 0.1
I found that I can set the number of partitions to 1 when calling cSPADE and that fixed the problem. However cSPADE does output a warning saying:
s1 <- cspade(trans, parameter = list(support = 0.1,maxlen=1), control = list(verbose = TRUE,numpart=1))
Warning message: In cspade(trans, parameter = list(support = 0.1, maxlen = 1), control = list(verbose = TRUE, : 'numpart' less than recommended
Do I need to heed this warning? What are the downsides of setting numpart=1 (forcing #partitions to be 1)? If there is, is there any way for me to get right answers without controlling this parameter?
