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Matt Strauser

2013-Sep-03 14:19 UTC

[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

	[[alternative HTML version deleted]]

David Winsemius

2013-Sep-03 20:09 UTC

head link

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

On Sep 3, 2013, at 7:19 AM, Matt Strauser wrote:
> 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
Generally subset does not need to have 'df$cond1' used. It uses
nonstandard evaluation and will assume that unquoted tokens are column names, so
this can be wrtten:
>  df1 <- subset(df, cond1 & cond2 )
>  df2 <- subset(df, cond3 & cond4)
>  df3 <- subset(df, cond5 & cond6 )
There is, however, this warning in the help file: "For programming it is
better to use the standard subsetting functions like `[`, and in particular the
non-standard evaluation of argument subset can have unanticipated
consequences." A similar warning is seen on the help page for
'with'. So this would be advised

df1 <- df[ df[, 'cond1'] & df[,'cond2'], ]
> 
> # Step 2 - rename the resulting global data frames
>   rename "df1" to prefix + "cond1cond2"
?assign  # e.g.:
# untested in absence of reproducible example
# You should learn to use dput()

assign(paste0(prefix, "cond1", "cond2"), df1,
envir=.GlobalEnv)

And please read the manual of your chosen mail-client and learn to post to Rhelp
in plain text.

-- David
>   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
> 
> 	[[alternative HTML version deleted]]
David Winsemius
Alameda, CA, USA

Greg Snow

2013-Sep-03 21:57 UTC

head link

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

This is FAQ 7.21.

The most important part of that FAQ is at the end where it says it is best
not to do this and better to use lists.  Having a function create
(overwrite) objects in the global environment is dangerous and can lead to
hard to find bugs.  It would be better to have your function return a list
containing the data frames, is there any reason that that would not work
for your case?


On Tue, Sep 3, 2013 at 8:19 AM, Matt Strauser <syntereo@gmail.com> wrote:
> 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
>
>         [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>


-- 
Gregory (Greg) L. Snow Ph.D.
538280@gmail.com

	[[alternative HTML version deleted]]

arun

2013-Sep-03 22:12 UTC

head link

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

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

??? [[alternative HTML version deleted]]

______________________________________________
R-help at r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.

R help - Sep 2013 - How to assign names to global data frames created in a function

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

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

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

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