I just need to confirm something with pattern matching folks. I have a factor with the following levels in a very large data set:

> levels(all$Classical.Statistic)
 [1] ""                        "AB;ABD"                  "CollapsedSteps"          "CR_P"                    "CR_Prop;CR_P;AB"
 [6] "NMK"                     "NMK;P"                   "NMK;P;ABD"               "P"                       "ABD"
[11] "CR_P;CollapsedSteps"     "NMK;AB;ABD"              "NMK;ABD"                 "NMK;P;AB"                "NMK;P;AB;ABD"
[16] "AB"                      "CRT;CollapsedSteps"      "NMK;AB"                  "CR_P;CRT;CollapsedSteps" "CR_Prop;CR_P"

I need to subset the rows in which the term "CollapsedSteps" appears. So, it may appear as "CollapsedSteps" or may appear as "CR_P;CRT;CollapsedSteps" as you can see above. I'm using grep as follows:

all[grep('CollapsedSteps', all$Classical.Statistic),]

to find any row in which the term "'CollapsedSteps" appears. Is this certain to catch all cases, or is there an intricacy that I may have missed.

Thank you
Harold



> sessionInfo()
R version 2.10.1 (2009-12-14)
i386-pc-mingw32

locale:
[1] LC_COLLATE=English_United States.1252  LC_CTYPE=English_United States.1252    LC_MONETARY=English_United States.1252
[4] LC_NUMERIC=C                           LC_TIME=English_United States.1252

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base

other attached packages:
[1] gdata_2.8.0

loaded via a namespace (and not attached):
[1] gtools_2.6.2 tools_2.10.1

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