R help - Apr 2015 - reshape data frame when one column has unequal number of entries

Hello!

I have my data frame x with 2 character columns:

x <- data.frame(a = numeric(), b = I(list()))
x[1:3,"a"] = 1:3
x[[1, "b"]] <- "a, b, c"
x[[2, "b"]] <- "d, e"
x[[3, "b"]] <- "f"
x$a = as.character(x$a)
x$b = as.character(x$b)
x
str(x)

I need to produce this data frame:

1  a
1  b
1  c
2  d
2  e
3  f

Is it possible without looping?
Thank you!


-- 
Dimitri Liakhovitski

Hi

I am not sure if this is more efficient than some loop

I just gave your data another column names.
> names(x)<-c("one", "two")
> x
  one     two
1   1 a, b, c
2   2    d, e
3   3       f
> s<-(strsplit(x$two, ","))
> s
[[1]]
[1] "a"  " b" " c"

[[2]]
[1] "d"  " e"

[[3]]
[1] "f"
> first<-rep(x$one     ,unlist(lapply(s, length)))
> data.frame(first, second=unlist(s))
  first second
1     1      a
2     1      b
3     1      c
4     2      d
5     2      e
6     3      f

Maybe you want to remove extra white space form your values. It is mentioned
somewhere in help pages to regular expressions

Cheers
Petr

> -----Original Message-----
> From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of Dimitri
> Liakhovitski
> Sent: Thursday, April 23, 2015 3:15 PM
> To: r-help
> Subject: [R] reshape data frame when one column has unequal number of
> entries
>
> Hello!
>
> I have my data frame x with 2 character columns:
>
> x <- data.frame(a = numeric(), b = I(list()))
> x[1:3,"a"] = 1:3
> x[[1, "b"]] <- "a, b, c"
> x[[2, "b"]] <- "d, e"
> x[[3, "b"]] <- "f"
> x$a = as.character(x$a)
> x$b = as.character(x$b)
> x
> str(x)
>
> I need to produce this data frame:
>
> 1  a
> 1  b
> 1  c
> 2  d
> 2  e
> 3  f
>
> Is it possible without looping?
> Thank you!
>
>
> --
> Dimitri Liakhovitski
>
> ______________________________________________
> 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.
________________________________
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Hi Dimitri

here is a quick crude way (needs some polishing)

data.frame(a = rep(x$a,sapply(sapply(x$b, strsplit, ", "), length)),
bunlist(sapply(x$b, strsplit, ", ")))

Duncan

Duncan Mackay
Department of Agronomy and Soil Science
University of New England
Armidale NSW 2351
Email: home: mackay at northnet.com.au

-----Original Message-----
From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of Dimitri
Liakhovitski
Sent: Thursday, 23 April 2015 23:15
To: r-help
Subject: [R] reshape data frame when one column has unequal number of
entries

Hello!

I have my data frame x with 2 character columns:

x <- data.frame(a = numeric(), b = I(list()))
x[1:3,"a"] = 1:3
x[[1, "b"]] <- "a, b, c"
x[[2, "b"]] <- "d, e"
x[[3, "b"]] <- "f"
x$a = as.character(x$a)
x$b = as.character(x$b)
x
str(x)

I need to produce this data frame:

1  a
1  b
1  c
2  d
2  e
3  f

Is it possible without looping?
Thank you!


-- 
Dimitri Liakhovitski

______________________________________________
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.

Thank you very much, everybody!

On Thu, Apr 23, 2015 at 10:38 AM, Duncan Mackay <dulcalma at bigpond.com>
wrote:
> Hi Dimitri
>
> here is a quick crude way (needs some polishing)
>
> data.frame(a = rep(x$a,sapply(sapply(x$b, strsplit, ", "),
length)), b> unlist(sapply(x$b, strsplit, ", ")))
>
> Duncan
>
> Duncan Mackay
> Department of Agronomy and Soil Science
> University of New England
> Armidale NSW 2351
> Email: home: mackay at northnet.com.au
>
> -----Original Message-----
> From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of Dimitri
> Liakhovitski
> Sent: Thursday, 23 April 2015 23:15
> To: r-help
> Subject: [R] reshape data frame when one column has unequal number of
> entries
>
> Hello!
>
> I have my data frame x with 2 character columns:
>
> x <- data.frame(a = numeric(), b = I(list()))
> x[1:3,"a"] = 1:3
> x[[1, "b"]] <- "a, b, c"
> x[[2, "b"]] <- "d, e"
> x[[3, "b"]] <- "f"
> x$a = as.character(x$a)
> x$b = as.character(x$b)
> x
> str(x)
>
> I need to produce this data frame:
>
> 1  a
> 1  b
> 1  c
> 2  d
> 2  e
> 3  f
>
> Is it possible without looping?
> Thank you!
>
>
> --
> Dimitri Liakhovitski
>
> ______________________________________________
> 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.
>


-- 
Dimitri Liakhovitski