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Kevin E. Thorpe

2018-May-02 17:11 UTC

[R] Converting a list to a data frame

I suspect this is pretty easy, but I'm having trouble figuring it out. 
Basically, I have a list of data frames such as the following example:

list(A=data.frame(x=1:2, y=3:4),B=data.frame(x=5:6,y=7:8))

I would like to turn this into  data frame where the list elements are 
essentially rbind'ed together and the element name becomes a new 
variable. For example, I would like to turn the list above into a data 
frame that looks like this:

data.frame(type=c("A","A","B","B"),x=c(1:2,5:6),y=c(3:4,7:8))

Appreciate any pointers.

Kevin

-- 
Kevin E. Thorpe
Head of Biostatistics,  Applied Health Research Centre (AHRC)
Li Ka Shing Knowledge Institute of St. Michael's Hospital
Assistant Professor, Dalla Lana School of Public Health
University of Toronto
email: kevin.thorpe at utoronto.ca  Tel: 416.864.5776  Fax: 416.864.3016

Huzefa Khalil

2018-May-02 17:23 UTC

head link

[R] Converting a list to a data frame

Hi Kevin,

There is probably a better way, but it can be done in two steps like this

temp <- list(A=data.frame(x=1:2, y=3:4),B=data.frame(x=5:6,y=7:8))

temp <- lapply(names(temp), function(n, temp) {
  temp[[n]]$type <- n
  return(temp[[n]])
}, temp = temp)

do.call(rbind, temp)



On Wed, May 2, 2018 at 1:11 PM, Kevin E. Thorpe <kevin.thorpe at
utoronto.ca>
wrote:
> I suspect this is pretty easy, but I'm having trouble figuring it out.
> Basically, I have a list of data frames such as the following example:
>
> list(A=data.frame(x=1:2, y=3:4),B=data.frame(x=5:6,y=7:8))
>
> I would like to turn this into  data frame where the list elements are
> essentially rbind'ed together and the element name becomes a new
variable.
> For example, I would like to turn the list above into a data frame that
> looks like this:
>
>
data.frame(type=c("A","A","B","B"),x=c(1:2,5:6),y=c(3:4,7:8))
>
> Appreciate any pointers.
>
> Kevin
>
> --
> Kevin E. Thorpe
> Head of Biostatistics,  Applied Health Research Centre (AHRC)
> Li Ka Shing Knowledge Institute of St. Michael's Hospital
> Assistant Professor, Dalla Lana School of Public Health
> University of Toronto
> email: kevin.thorpe at utoronto.ca  Tel: 416.864.5776  Fax: 416.864.3016
>
> ______________________________________________
> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posti
> ng-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
	[[alternative HTML version deleted]]

William Dunlap

2018-May-02 17:28 UTC

head link

[R] Converting a list to a data frame

> x1 <- do.call(rbind, c(x, list(make.row.names=FALSE)))
> x2 <- cbind(type=rep(names(x), vapply(x, nrow, 0)), x1)
> str(x2)'data.frame':   4 obs. of  3 variables:
 $ type: Factor w/ 2 levels "A","B": 1 1 2 2
 $ x   : int  1 2 5 6
 $ y   : int  3 4 7 8


Bill Dunlap
TIBCO Software
wdunlap tibco.com

On Wed, May 2, 2018 at 10:11 AM, Kevin E. Thorpe <kevin.thorpe at
utoronto.ca>
wrote:
> I suspect this is pretty easy, but I'm having trouble figuring it out.
> Basically, I have a list of data frames such as the following example:
>
> list(A=data.frame(x=1:2, y=3:4),B=data.frame(x=5:6,y=7:8))
>
> I would like to turn this into  data frame where the list elements are
> essentially rbind'ed together and the element name becomes a new
variable.
> For example, I would like to turn the list above into a data frame that
> looks like this:
>
>
data.frame(type=c("A","A","B","B"),x=c(1:2,5:6),y=c(3:4,7:8))
>
> Appreciate any pointers.
>
> Kevin
>
> --
> Kevin E. Thorpe
> Head of Biostatistics,  Applied Health Research Centre (AHRC)
> Li Ka Shing Knowledge Institute of St. Michael's Hospital
> Assistant Professor, Dalla Lana School of Public Health
> University of Toronto
> email: kevin.thorpe at utoronto.ca  Tel: 416.864.5776  Fax: 416.864.3016
>
> ______________________________________________
> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posti
> ng-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
	[[alternative HTML version deleted]]

Eivind K. Dovik

2018-May-02 17:38 UTC

head link

[R] Converting a list to a data frame

On Wed, 2 May 2018, Kevin E. Thorpe wrote:
> I suspect this is pretty easy, but I'm having trouble figuring it out. 
> Basically, I have a list of data frames such as the following example:
>
> list(A=data.frame(x=1:2, y=3:4),B=data.frame(x=5:6,y=7:8))
>
> I would like to turn this into  data frame where the list elements are 
> essentially rbind'ed together and the element name becomes a new
variable.
> For example, I would like to turn the list above into a data frame that
looks
> like this:
>
>
data.frame(type=c("A","A","B","B"),x=c(1:2,5:6),y=c(3:4,7:8))
>
> Appreciate any pointers.
>
> Kevin
Hi, Kevin.

Here's code that will generate your desired data frame.

# List as provided
thelist <- list(A=data.frame(x=1:2, y=3:4),B=data.frame(x=5:6,y=7:8))
thelist

# Creating the type-vector
type <- c()
for(i in 1:length(thelist)){
   type <- c(type, rep(names(thelist)[i], sapply(thelist, nrow)[i]))
}

# Creating the data frame
df <- data.frame(type, do.call(rbind.data.frame, c(thelist, make.row.names 
= FALSE)))
df


Kind regards,
Eivind K. Dovik
Bergen, NO



>
> -- 
> Kevin E. Thorpe
> Head of Biostatistics,  Applied Health Research Centre (AHRC)
> Li Ka Shing Knowledge Institute of St. Michael's Hospital
> Assistant Professor, Dalla Lana School of Public Health
> University of Toronto
> email: kevin.thorpe at utoronto.ca  Tel: 416.864.5776  Fax: 416.864.3016
>
> ______________________________________________
> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
> 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.
>

Jeff Newmiller

2018-May-02 18:53 UTC

head link

[R] Converting a list to a data frame

Another approach:

########
library(tidyr)
L <- list( A = data.frame( x=1:2, y=3:4 )
          , B = data.frame( x=5:6, y=7:8 )
          )
D <- data.frame( Type = names( L )
                , stringsAsFactors = FALSE
                )
D$data <- L
unnest(D, data)
#>   Type x y
#> 1    A 1 3
#> 2    A 2 4
#> 3    B 5 7
#> 4    B 6 8
########

On Wed, 2 May 2018, Eivind K. Dovik wrote:
> On Wed, 2 May 2018, Kevin E. Thorpe wrote:
>
>> I suspect this is pretty easy, but I'm having trouble figuring it
out.
>> Basically, I have a list of data frames such as the following example:
>> 
>> list(A=data.frame(x=1:2, y=3:4),B=data.frame(x=5:6,y=7:8))
>> 
>> I would like to turn this into  data frame where the list elements are 
>> essentially rbind'ed together and the element name becomes a new
variable.
>> For example, I would like to turn the list above into a data frame that
>> looks like this:
>> 
>>
data.frame(type=c("A","A","B","B"),x=c(1:2,5:6),y=c(3:4,7:8))
>> 
>> Appreciate any pointers.
>> 
>> Kevin
>
> Hi, Kevin.
>
> Here's code that will generate your desired data frame.
>
> # List as provided
> thelist <- list(A=data.frame(x=1:2, y=3:4),B=data.frame(x=5:6,y=7:8))
> thelist
>
> # Creating the type-vector
> type <- c()
> for(i in 1:length(thelist)){
>  type <- c(type, rep(names(thelist)[i], sapply(thelist, nrow)[i]))
> }
>
> # Creating the data frame
> df <- data.frame(type, do.call(rbind.data.frame, c(thelist,
make.row.names =
> FALSE)))
> df
>
>
> Kind regards,
> Eivind K. Dovik
> Bergen, NO
>
>
>
>
>> 
>> -- 
>> Kevin E. Thorpe
>> Head of Biostatistics,  Applied Health Research Centre (AHRC)
>> Li Ka Shing Knowledge Institute of St. Michael's Hospital
>> Assistant Professor, Dalla Lana School of Public Health
>> University of Toronto
>> email: kevin.thorpe at utoronto.ca  Tel: 416.864.5776  Fax:
416.864.3016
>> 
>> ______________________________________________
>> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
>> 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 at r-project.org mailing list -- To UNSUBSCRIBE and more, see
> 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.
>
---------------------------------------------------------------------------
Jeff Newmiller                        The     .....       .....  Go Live...
DCN:<jdnewmil at dcn.davis.ca.us>        Basics: ##.#.       ##.#.  Live
Go...
                                       Live:   OO#.. Dead: OO#..  Playing
Research Engineer (Solar/Batteries            O.O#.       #.O#.  with
/Software/Embedded Controllers)               .OO#.       .OO#.  rocks...1k

Tóth Dénes

2018-May-02 19:30 UTC

head link

[R] Converting a list to a data frame

On 05/02/2018 07:11 PM, Kevin E. Thorpe wrote:> I suspect this is pretty easy, but I'm having trouble figuring it out. 
> Basically, I have a list of data frames such as the following example:
> 
> list(A=data.frame(x=1:2, y=3:4),B=data.frame(x=5:6,y=7:8))
> 
> I would like to turn this into  data frame where the list elements are 
> essentially rbind'ed together and the element name becomes a new 
> variable. For example, I would like to turn the list above into a data 
> frame that looks like this:
> 
>
data.frame(type=c("A","A","B","B"),x=c(1:2,5:6),y=c(3:4,7:8))
> 
> Appreciate any pointers.
Hi Kevin,

data.table::rbindlist does exactly what you want in a very efficient way:

library(data.table)
dat <- list(A=data.frame(x=1:2, y=3:4),B=data.frame(x=5:6,y=7:8))
rbindlist(dat, idcol = "type")

Regards,
Denes

> 
> Kevin
>

David L Carlson

2018-May-02 20:50 UTC

head link

[R] Converting a list to a data frame

Or add the type column first and then rbind:

x <- list(A=data.frame(x=1:2, y=3:4),B=data.frame(x=5:6,y=7:8))
x2 <- do.call(rbind, lapply(names(x), function(z) 
      data.frame(type=z, dat[[z]])))

----------------------------------------
David L Carlson
Department of Anthropology
Texas A&M University
College Station, TX 77843-4352

-----Original Message-----
From: R-help <r-help-bounces at r-project.org> On Behalf Of William Dunlap
via R-help
Sent: Wednesday, May 2, 2018 12:28 PM
To: Kevin E. Thorpe <kevin.thorpe at utoronto.ca>
Cc: R Help Mailing List <r-help at r-project.org>
Subject: Re: [R] Converting a list to a data frame
> x1 <- do.call(rbind, c(x, list(make.row.names=FALSE)))
> x2 <- cbind(type=rep(names(x), vapply(x, nrow, 0)), x1)
> str(x2)'data.frame':   4 obs. of  3 variables:
 $ type: Factor w/ 2 levels "A","B": 1 1 2 2
 $ x   : int  1 2 5 6
 $ y   : int  3 4 7 8


Bill Dunlap
TIBCO Software
wdunlap tibco.com

On Wed, May 2, 2018 at 10:11 AM, Kevin E. Thorpe <kevin.thorpe at
utoronto.ca>
wrote:
> I suspect this is pretty easy, but I'm having trouble figuring it out.
> Basically, I have a list of data frames such as the following example:
>
> list(A=data.frame(x=1:2, y=3:4),B=data.frame(x=5:6,y=7:8))
>
> I would like to turn this into  data frame where the list elements are 
> essentially rbind'ed together and the element name becomes a new
variable.
> For example, I would like to turn the list above into a data frame 
> that looks like this:
>
>
data.frame(type=c("A","A","B","B"),x=c(1:2,5:6),y=c(3:4,7:8))
>
> Appreciate any pointers.
>
> Kevin
>
> --
> Kevin E. Thorpe
> Head of Biostatistics,  Applied Health Research Centre (AHRC) Li Ka 
> Shing Knowledge Institute of St. Michael's Hospital Assistant 
> Professor, Dalla Lana School of Public Health University of Toronto
> email: kevin.thorpe at utoronto.ca  Tel: 416.864.5776  Fax: 416.864.3016
>
> ______________________________________________
> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see 
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posti 
> ng-guide.html and provide commented, minimal, self-contained, 
> reproducible code.
>
	[[alternative HTML version deleted]]

______________________________________________
R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
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.

Jeff Newmiller

2018-May-03 05:58 UTC

head link

[R] Converting a list to a data frame

This is very nice to learn about, Denis, but it seems only fair to point out
that the result of rbindlist is not a data frame.  You can convert it to a data
frame easily, but the copy and indexing semantics of data tables are quite
different than data tables, which could be a real headache for someone not
prepared for those differences. (To learn more, read the data tables vignette.)

Tibbles  (as produced by unnest in my previous response) are not data tables
either, but they behave much more like data frames than data tables do.

On May 2, 2018 1:30:37 PM MDT, "T?th D?nes" <toth.denes at
kogentum.hu> wrote:>
>
>On 05/02/2018 07:11 PM, Kevin E. Thorpe wrote:
>> I suspect this is pretty easy, but I'm having trouble figuring it
>out. 
>> Basically, I have a list of data frames such as the following
>example:
>> 
>> list(A=data.frame(x=1:2, y=3:4),B=data.frame(x=5:6,y=7:8))
>> 
>> I would like to turn this into  data frame where the list elements
>are 
>> essentially rbind'ed together and the element name becomes a new 
>> variable. For example, I would like to turn the list above into a
>data 
>> frame that looks like this:
>> 
>>
data.frame(type=c("A","A","B","B"),x=c(1:2,5:6),y=c(3:4,7:8))
>> 
>> Appreciate any pointers.
>
>Hi Kevin,
>
>data.table::rbindlist does exactly what you want in a very efficient
>way:
>
>library(data.table)
>dat <- list(A=data.frame(x=1:2, y=3:4),B=data.frame(x=5:6,y=7:8))
>rbindlist(dat, idcol = "type")
>
>Regards,
>Denes
>
>
>> 
>> Kevin
>>
>
>______________________________________________
>R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
>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.
-- 
Sent from my phone. Please excuse my brevity.

Bill Poling

2018-May-04 12:18 UTC

head link

[R] Converting a list to a data frame

Good morning.

Novice usR. Here.

I am following this string, among many, learning as I go.

Quick question please?

I thought that perhaps ata.frame was part of the zoo pkg, b/c when I searched it
came up in help?

However, evidently not or I am not using it properly.

Please advise, thank you.
x <- list(A=data.frame(x=1:2, y=3:4),B=data.frame(x=5:6,y=7:8))
x2 <- do.call(rbind, lapply(names(x), function(z)
ata.frame(type=z, dat[[z]])))
#Error in ata.frame(type = z, dat[[z]]) : could not find function
"ata.frame"

?ata.frame
??ata.frame #Looks like it's part of the zoo package?
install.packages("zoo")

#Typo: dat[[z]] should be x[[z]]:

x <- list(A=data.frame(x=1:2, y=3:4),B=data.frame(x=5:6,y=7:8))
x2 <- do.call(rbind, lapply(names(x), function(z)
ata.frame(type=z, x[[z]])))
#Error in ata.frame(type = z, dat[[z]]) : still cannot find function
"ata.frame"?

William H. Poling, Ph.D.

From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of Huzefa Khalil
Sent: Wednesday, May 02, 2018 1:24 PM
To: Kevin E. Thorpe <kevin.thorpe at utoronto.ca>
Cc: R Help Mailing List <r-help at r-project.org>
Subject: Re: [R] Converting a list to a data frame

Hi Kevin,

There is probably a better way, but it can be done in two steps like this

temp <- list(A=data.frame(x=1:2, y=3:4),B=data.frame(x=5:6,y=7:8))

temp <- lapply(names(temp), function(n, temp) {
temp[[n]]$type <- n
return(temp[[n]])
}, temp = temp)

do.call(rbind, temp)

On Wed, May 2, 2018 at 1:11 PM, Kevin E. Thorpe <kevin.thorpe at
utoronto.ca<mailto:kevin.thorpe at utoronto.ca>>
wrote:
> I suspect this is pretty easy, but I'm having trouble figuring it out.
> Basically, I have a list of data frames such as the following example:
>
> list(A=data.frame(x=1:2, y=3:4),B=data.frame(x=5:6,y=7:8))
>
> I would like to turn this into data frame where the list elements are
> essentially rbind'ed together and the element name becomes a new
variable.
> For example, I would like to turn the list above into a data frame that
> looks like this:
>
>
data.frame(type=c("A","A","B","B"),x=c(1:2,5:6),y=c(3:4,7:8))
>
> Appreciate any pointers.
>
> Kevin
>
> --
> Kevin E. Thorpe
> Head of Biostatistics, Applied Health Research Centre (AHRC)
> Li Ka Shing Knowledge Institute of St. Michael's Hospital
> Assistant Professor, Dalla Lana School of Public Health
> University of Toronto
> email: kevin.thorpe at utoronto.ca<mailto:kevin.thorpe at
utoronto.ca> Tel: 416.864.5776 Fax: 416.864.3016
>
> ______________________________________________
> R-help at r-project.org<mailto:R-help at r-project.org> mailing list
-- To UNSUBSCRIBE and more, see
>
https://stat.ethz.ch/mailman/listinfo/r-help<https://stat.ethz.ch/mailman/listinfo/r-help>
> PLEASE do read the posting guide
http://www.R-project.org/posti<http://www.R-project.org/posti>
> ng-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
[[alternative HTML version deleted]]

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

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