[R] How to assign names to global data frames created in a function

[arun]

Hi,
May be this helps you in getting started.


set.seed(29)
 df1<- as.data.frame(matrix(sample(1:20,5*10,replace=TRUE),5,10))
 cond<- c("V1eq2","V8eq2","V6eq4orV8eq7")


fun1<- function(df,prefix,cond){
lst1<- list(df[df$V1==2,],df[df$V8==2,],df[df$V6==4|df$V8==7,]) 
for(i in seq_along(cond)){
 assign(paste(prefix,cond[i],sep="_"),lst1[[i]],envir=.GlobalEnv)
 print(paste(prefix,cond[i],sep="_"))}
 }

fun1(df1,"frame1",cond)
#[1] "frame1_V1eq2"
#[1] "frame1_V8eq2"
#[1] "frame1_V6eq4orV8eq7"
 frame1_V1eq2
#  V1 V2 V3 V4 V5 V6 V7 V8 V9 V10
#1  2  2 20 17 14  8  8  2 13  18
 frame1_V8eq2
#  V1 V2 V3 V4 V5 V6 V7 V8 V9 V10
#1  2  2 20 17 14  8  8  2 13  18
#5 12  5  4  8 13  4 10  2  2  13
 frame1_V6eq4orV8eq7
#  V1 V2 V3 V4 V5 V6 V7 V8 V9 V10
#3  3 18  7  8 20 18  2  7 20  15
#4  7  3 13 18 20 14 15  7 14  12
#5 12  5  4  8 13  4 10  2  2  13

A.K.



----- Original Message -----
From: Matt Strauser <syntereo at gmail.com>
To: r-help at r-project.org
Cc: 
Sent: Tuesday, September 3, 2013 10:19 AM
Subject: [R] How to assign names to global data frames created in a function

I have several data frames containing similar data. I'd like to pass these
data frames to a function for processing. The function would create newly
named "global" data frames containing the processed data. I cannot figure
out how to assign names to the data frames in Step 1 or Step 2 in the
following example:

# sample function in pseudo code
processdf <- function(df, prefix) {
# df - data frame containing data for processing
# prefix - string to become the first part of the names of the resulting
data frames
# Step 1 - processs df into several subsets
  df1 <<- subset(df, df$cond1 & df$cond2 & ...)
  df2 <<- subset(df, df$cond3 & df$cond4 & ...)
  df3 <<- subset(df, df$cond5 & df$cond6 & ...)
# and so on....for many more steps with resulting data frames

# Step 2 - rename the resulting global data frames
   rename "df1" to prefix + "cond1cond2"
   rename "df2" to prefix + "cond3cond4"
   rename "df3" to prefix + "cond5cond6"
# and so on for the remaining data frames
}

Example using data frames: frame1 and frame2:

processdf(frame1, "frame1")
# produces these data frames:
frame1cond1cond2
frame1cond3cond4
frame1cond5cond6

processdf(frame2, "frame2")
# produces these data frames:
frame2cond1cond2
frame2cond3cond4
frame2cond5cond6

Thank you for your thoughts,
Matt

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