help with apply (lapply or sapply not sure)

Thu, Jul 25, 2013 11:53 PM

Hi

I would just use for cycle. Something like

lll <- vector("list", length(InputFiles))
for (i in InputFiles) {

everything what you want to do for each file
you can store it in a list
lll[[i]] <- whatever you want to store there

}

After populating list you can do anything with it.

Regards
Petr

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
project.org] On Behalf Of Robert Lynch
Sent: Friday, July 26, 2013 2:46 AM
To: r-help at r-project.org
Subject: [R] help with apply (lapply or sapply not sure)

I am reading in a bunch of files and then processing them all in the
same
way.

I am sure there as a better way then to copy and past the code for each
file. Here is what I've done so far

InputFiles<-
as.character(list.files("~/ISLE/RWork/DataWarehouseMining/byCourse/"))
#Path to the Course data files

for (i in InputFiles) {
  #
print(head(read.csv(paste("~/ISLE/RWork/DataWarehouseMining/byCourse/",
i, sep=""))))
  print(paste("Reading file
~/ISLE/RWork/DataWarehouseMining/byCourse/", i,
sep=","))
  assign(i,
read.csv(paste("~/ISLE/RWork/DataWarehouseMining/byCourse/", i,
sep="")))
}#note last file is NOT a course file by the student information.
Master<-StudentInfoForRobertWUnitAt7A_2.csv #this is the last file

CourseFiles <-InputFiles[- c(15,16)] # ignore the student info
...7A.csv &
...7A_2.csv

#for each file I do the following
#Bis 101
summary(BigInstBIS101.csv)
B101 <- BigInstBIS101.csv[-c(3,4,8)]
summary(B101)
B101$WH_ID <- as.factor(B101$WH_ID)
B101$SID <- as.factor(B101$SID)
B101$TERM <- as.factor(B101$TERM)
B101$CRN <- as.factor(B101$CRN)
B101$CRN_TRM <- as.factor(B101$CRN_TRM)
B101$INST_NUM <- as.factor(B101$INST_NUM)
B101$zGrade <- with(B101, ave(GRADE., list(TERM, INST_NUM), FUN =
scale))
write.csv(B101,"B101.csv", row.names = FALSE)

#Bis 2A
B2A <- BigInstBIS2A.csv[-c(3,4,8)]
summary(B2A)
B2A$WH_ID <- as.factor(B2A$WH_ID)
B2A$SID <- as.factor(B2A$SID)
B2A$TERM <- as.factor(B2A$TERM)
B2A$CRN <- as.factor(B2A$CRN)
B2A$CRN_TRM <- as.factor(B2A$CRN_TRM)
B2A$INST_NUM <- as.factor(B2A$INST_NUM)
B2A$zGrade <- with(B2A, ave(GRADE., list(TERM, INST_NUM), FUN = scale))
write.csv(B2A,"B2A.csv", row.names = FALSE)

And so on for another 12 courses, however I am changing what I am doing
as
part of the reading in the file and don't want to replace the code in
14
different places.
suggestions?  Thanks!

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help with apply (lapply or sapply not sure)

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