Re: [R] idiom for constructing data frame
On 31 Mar 2015, at 20:55 , William Dunlap wdun...@tibco.com wrote: You can use structure() to attach the names to a list that is input to data.frame. E.g., dfNames - c(First, Second Name) data.frame(lapply(structure(dfNames, names=dfNames), function(name)rep(NA_real_, 5))) Yes, I cooked up something similar: names - c(foo,bar,baz) names(names) - names # confuse 'em as.data.frame(lapply(names, function(x) rep(NA_real_,10))) but wouldn't it be more to the point to do df - as.data.frame(rep(list(rep(NA_real_, 10)),3)) names(df) - names ? The lapply() approach could be generalized to a vector of column classes, though. A general solution looks impracticable; once you start considering how to specify factor columns with each their own level set, things get a bit out of hand. -pd Bill Dunlap TIBCO Software wdunlap tibco.com On Tue, Mar 31, 2015 at 11:37 AM, Sarah Goslee sarah.gos...@gmail.com wrote: Hi, Duncan Murdoch suggested: The matrix() function has a dimnames argument, so you could do this: names - c(strat, id, pid) data.frame(matrix(NA, nrow=10, ncol=3, dimnames=list(NULL, names))) That's a definite improvement, thanks. But no way to skip matrix()? It just seems unRlike, although since it's only full of NA values there are no coercion issues with column types or anything, so it doesn't hurt. It's just inelegant. :) Sarah -- Sarah Goslee http://www.functionaldiversity.org __ R-help@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. [[alternative HTML version deleted]] __ R-help@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. -- Peter Dalgaard, Professor, Center for Statistics, Copenhagen Business School Solbjerg Plads 3, 2000 Frederiksberg, Denmark Phone: (+45)38153501 Email: pd@cbs.dk Priv: pda...@gmail.com __ R-help@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.
Re: [R] idiom for constructing data frame
but wouldn't it be more to the point to do df - as.data.frame(rep(list(rep(NA_real_, 10)),3)) names(df) - names As a matter of personal style (and functional programming sensibility), I prefer not to make named objects and then modify them. Also, the names coming out of that as.data.frame call are exceedingly ugly and I'd rather not generate them at all. Also adding the names after calling data.frame means can give different results than passing them into data.frame(), which can mangle nonsyntactic names like Second Name into Second.Name. It is often preferable, but it is different. Bill Dunlap TIBCO Software wdunlap tibco.com On Fri, Apr 3, 2015 at 5:51 AM, peter dalgaard pda...@gmail.com wrote: On 31 Mar 2015, at 20:55 , William Dunlap wdun...@tibco.com wrote: You can use structure() to attach the names to a list that is input to data.frame. E.g., dfNames - c(First, Second Name) data.frame(lapply(structure(dfNames, names=dfNames), function(name)rep(NA_real_, 5))) Yes, I cooked up something similar: names - c(foo,bar,baz) names(names) - names # confuse 'em as.data.frame(lapply(names, function(x) rep(NA_real_,10))) but wouldn't it be more to the point to do df - as.data.frame(rep(list(rep(NA_real_, 10)),3)) names(df) - names ? The lapply() approach could be generalized to a vector of column classes, though. A general solution looks impracticable; once you start considering how to specify factor columns with each their own level set, things get a bit out of hand. -pd Bill Dunlap TIBCO Software wdunlap tibco.com On Tue, Mar 31, 2015 at 11:37 AM, Sarah Goslee sarah.gos...@gmail.com wrote: Hi, Duncan Murdoch suggested: The matrix() function has a dimnames argument, so you could do this: names - c(strat, id, pid) data.frame(matrix(NA, nrow=10, ncol=3, dimnames=list(NULL, names))) That's a definite improvement, thanks. But no way to skip matrix()? It just seems unRlike, although since it's only full of NA values there are no coercion issues with column types or anything, so it doesn't hurt. It's just inelegant. :) Sarah -- Sarah Goslee http://www.functionaldiversity.org __ R-help@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. [[alternative HTML version deleted]] __ R-help@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. -- Peter Dalgaard, Professor, Center for Statistics, Copenhagen Business School Solbjerg Plads 3, 2000 Frederiksberg, Denmark Phone: (+45)38153501 Email: pd@cbs.dk Priv: pda...@gmail.com [[alternative HTML version deleted]] __ R-help@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.
Re: [R] idiom for constructing data frame
On Tue, Mar 31, 2015 at 6:42 PM, Sarah Goslee sarah.gos...@gmail.com wrote: On Tue, Mar 31, 2015 at 6:35 PM, Richard M. Heiberger r...@temple.edu wrote: I got rid of the extra column. data.frame(r=seq(8), foo=NA, bar=NA, row.names=r) Brilliant! After much fussing, including a disturbing detour into nested lapply statements from which I barely emerged with my sanity (arguable, I suppose), here is a one-liner that creates a data frame of arbitrary number of rows given an existing data frame as template for column number and name: n - 8 df1 - data.frame(A=runif(9), B=runif(9)) do.call(data.frame, setNames(c(list(seq(n), r), as.list(rep(NA, ncol(df1, c(r, row.names, colnames(df1 It's not elegant, but it is fairly R-ish. I should probably stop hunting for an elegant solution now. Given a template df, you can create a new df with subsetting: df2 - df1[rep(NA_real_, 8), ] rownames(df2) - NULL df2 This has the added benefit of preserving the types. Hadley -- http://had.co.nz/ __ R-help@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.
Re: [R] idiom for constructing data frame
On 03 Apr 2015, at 16:46 , William Dunlap wdun...@tibco.com wrote: df - as.data.frame(rep(list(rep(NA_real_, 10)),3)) names(df) - names As a matter of personal style (and functional programming sensibility), I prefer not to make named objects and then modify them. Also, the names coming out of that as.data.frame call are exceedingly ugly and I'd rather not generate them at all. Ah, yes, I missed the generation of intermediate names. You can name the list before as.data.frame, though: l - rep(list(rep(NA_real_, 10)),3) names(l) - names as.data.frame(l) or as a one-liner: as.data.frame(structure(rep(list(rep(NA_real_, 10)), 3) , .Names=names)) -- Peter Dalgaard, Professor, Center for Statistics, Copenhagen Business School Solbjerg Plads 3, 2000 Frederiksberg, Denmark Phone: (+45)38153501 Email: pd@cbs.dk Priv: pda...@gmail.com __ R-help@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.
Re: [R] idiom for constructing data frame
You can make it as elegant as you want, e.g.,
make.empty.df - function(nrow,ncol, names) {
if(length(names) %% ncol != 0) stop(Lenght of names is not a
multiple of the number of colums)
data.frame(matrix(NA, nrow, ncol, dimnames = list(NULL, names)))
}
Best,
Ista
On Tue, Mar 31, 2015 at 2:37 PM, Sarah Goslee sarah.gos...@gmail.com wrote:
Hi,
Duncan Murdoch suggested:
The matrix() function has a dimnames argument, so you could do this:
names - c(strat, id, pid)
data.frame(matrix(NA, nrow=10, ncol=3, dimnames=list(NULL, names)))
That's a definite improvement, thanks. But no way to skip matrix()? It
just seems unRlike, although since it's only full of NA values there
are no coercion issues with column types or anything, so it doesn't
hurt. It's just inelegant. :)
Sarah
--
Sarah Goslee
http://www.functionaldiversity.org
__
R-help@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@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.
Re: [R] idiom for constructing data frame
You can use structure() to attach the names to a list that is input to data.frame. E.g., dfNames - c(First, Second Name) data.frame(lapply(structure(dfNames, names=dfNames), function(name)rep(NA_real_, 5))) Bill Dunlap TIBCO Software wdunlap tibco.com On Tue, Mar 31, 2015 at 11:37 AM, Sarah Goslee sarah.gos...@gmail.com wrote: Hi, Duncan Murdoch suggested: The matrix() function has a dimnames argument, so you could do this: names - c(strat, id, pid) data.frame(matrix(NA, nrow=10, ncol=3, dimnames=list(NULL, names))) That's a definite improvement, thanks. But no way to skip matrix()? It just seems unRlike, although since it's only full of NA values there are no coercion issues with column types or anything, so it doesn't hurt. It's just inelegant. :) Sarah -- Sarah Goslee http://www.functionaldiversity.org __ R-help@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. [[alternative HTML version deleted]] __ R-help@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.
Re: [R] idiom for constructing data frame
Hi, Duncan Murdoch suggested: The matrix() function has a dimnames argument, so you could do this: names - c(strat, id, pid) data.frame(matrix(NA, nrow=10, ncol=3, dimnames=list(NULL, names))) That's a definite improvement, thanks. But no way to skip matrix()? It just seems unRlike, although since it's only full of NA values there are no coercion issues with column types or anything, so it doesn't hurt. It's just inelegant. :) Sarah -- Sarah Goslee http://www.functionaldiversity.org __ R-help@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.
Re: [R] idiom for constructing data frame
I just snagged this from Duncan Murdoch's reply to the same question: # Create an empty dataframe to hold the results df - data.frame(strat=NA, id=NA, pid=NA)[rep(1, length(sel)),] This skips matrix(), but how to set the column names programmatically within a function? Sarah, still sure I'm missing something obvious On Tue, Mar 31, 2015 at 1:46 PM, Sarah Goslee sarah.gos...@gmail.com wrote: Hi folks, I KNOW there has to be a way to do this more elegantly, but I consistently fail to come up with it, as I was just reminded while writing an example for a query on this list. What's a nifty way to construct a data frame of a given size? The only way I know of it to use matrix(), eg data.frame(matrix(NA, nrow=10, ncol=3)) and then to set the colnames in a second step. This comes up a lot when pre-allocated a data frame before using a loop: I know the size and column names, but want an empty structure to fill later. Sarah -- Sarah Goslee http://www.functionaldiversity.org __ R-help@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] idiom for constructing data frame
Hi folks, I KNOW there has to be a way to do this more elegantly, but I consistently fail to come up with it, as I was just reminded while writing an example for a query on this list. What's a nifty way to construct a data frame of a given size? The only way I know of it to use matrix(), eg data.frame(matrix(NA, nrow=10, ncol=3)) and then to set the colnames in a second step. This comes up a lot when pre-allocated a data frame before using a loop: I know the size and column names, but want an empty structure to fill later. Sarah -- Sarah Goslee http://www.functionaldiversity.org __ R-help@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.
Re: [R] idiom for constructing data frame
On 31/03/2015 1:52 PM, Sarah Goslee wrote: I just snagged this from Duncan Murdoch's reply to the same question: # Create an empty dataframe to hold the results df - data.frame(strat=NA, id=NA, pid=NA)[rep(1, length(sel)),] This skips matrix(), but how to set the column names programmatically within a function? Sarah, still sure I'm missing something obvious The matrix() function has a dimnames argument, so you could do this: names - c(strat, id, pid) data.frame(matrix(NA, nrow=10, ncol=3, dimnames=list(NULL, names))) Duncan Murdoch On Tue, Mar 31, 2015 at 1:46 PM, Sarah Goslee sarah.gos...@gmail.com wrote: Hi folks, I KNOW there has to be a way to do this more elegantly, but I consistently fail to come up with it, as I was just reminded while writing an example for a query on this list. What's a nifty way to construct a data frame of a given size? The only way I know of it to use matrix(), eg data.frame(matrix(NA, nrow=10, ncol=3)) and then to set the colnames in a second step. This comes up a lot when pre-allocated a data frame before using a loop: I know the size and column names, but want an empty structure to fill later. Sarah __ R-help@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.
Re: [R] idiom for constructing data frame
On Tue, Mar 31, 2015 at 6:35 PM, Richard M. Heiberger r...@temple.edu wrote:
I got rid of the extra column.
data.frame(r=seq(8), foo=NA, bar=NA, row.names=r)
Brilliant!
After much fussing, including a disturbing detour into nested lapply
statements from which I barely emerged with my sanity (arguable, I
suppose), here is a one-liner that creates a data frame of arbitrary
number of rows given an existing data frame as template for column
number and name:
n - 8
df1 - data.frame(A=runif(9), B=runif(9))
do.call(data.frame, setNames(c(list(seq(n), r), as.list(rep(NA,
ncol(df1, c(r, row.names, colnames(df1
It's not elegant, but it is fairly R-ish. I should probably stop
hunting for an elegant solution now.
Thanks, everyone!
Sarah
Rich
On Tue, Mar 31, 2015 at 6:18 PM, Sven E. Templer sven.temp...@gmail.com
wrote:
If you don't mind an extra column, you could use something similar to:
data.frame(r=seq(8),foo=NA,bar=NA)
If you do, here is another approach (see function body):
empty.frame - function (r = 1, n = 1, fill = NA_real_) {
data.frame(setNames(lapply(rep(fill, length(n)), rep, times=r), n))
}
empty.frame()
empty.frame(, seq(3))
empty.frame(8, c(foo, bar))
I could not put it in one line either, without retyping at least one
argument (n in this case).
So I suggest a function is the way to go for a simplified syntax ...
Thanks to all for the ideas!
Sven
On 31 March 2015 at 20:55, William Dunlap wdun...@tibco.com wrote:
You can use structure() to attach the names to a list that is input to
data.frame.
E.g.,
dfNames - c(First, Second Name)
data.frame(lapply(structure(dfNames, names=dfNames),
function(name)rep(NA_real_, 5)))
Bill Dunlap
TIBCO Software
wdunlap tibco.com
On Tue, Mar 31, 2015 at 11:37 AM, Sarah Goslee sarah.gos...@gmail.com
wrote:
Hi,
Duncan Murdoch suggested:
The matrix() function has a dimnames argument, so you could do this:
names - c(strat, id, pid)
data.frame(matrix(NA, nrow=10, ncol=3, dimnames=list(NULL, names)))
That's a definite improvement, thanks. But no way to skip matrix()? It
just seems unRlike, although since it's only full of NA values there
are no coercion issues with column types or anything, so it doesn't
hurt. It's just inelegant. :)
Sarah
--
Sarah Goslee
http://www.functionaldiversity.org
__
R-help@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.
Re: [R] idiom for constructing data frame
If you don't mind an extra column, you could use something similar to:
data.frame(r=seq(8),foo=NA,bar=NA)
If you do, here is another approach (see function body):
empty.frame - function (r = 1, n = 1, fill = NA_real_) {
data.frame(setNames(lapply(rep(fill, length(n)), rep, times=r), n))
}
empty.frame()
empty.frame(, seq(3))
empty.frame(8, c(foo, bar))
I could not put it in one line either, without retyping at least one
argument (n in this case).
So I suggest a function is the way to go for a simplified syntax ...
Thanks to all for the ideas!
Sven
On 31 March 2015 at 20:55, William Dunlap wdun...@tibco.com wrote:
You can use structure() to attach the names to a list that is input to
data.frame.
E.g.,
dfNames - c(First, Second Name)
data.frame(lapply(structure(dfNames, names=dfNames),
function(name)rep(NA_real_, 5)))
Bill Dunlap
TIBCO Software
wdunlap tibco.com
On Tue, Mar 31, 2015 at 11:37 AM, Sarah Goslee sarah.gos...@gmail.com
wrote:
Hi,
Duncan Murdoch suggested:
The matrix() function has a dimnames argument, so you could do this:
names - c(strat, id, pid)
data.frame(matrix(NA, nrow=10, ncol=3, dimnames=list(NULL, names)))
That's a definite improvement, thanks. But no way to skip matrix()? It
just seems unRlike, although since it's only full of NA values there
are no coercion issues with column types or anything, so it doesn't
hurt. It's just inelegant. :)
Sarah
--
Sarah Goslee
http://www.functionaldiversity.org
__
R-help@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.
[[alternative HTML version deleted]]
__
R-help@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.
[[alternative HTML version deleted]]
__
R-help@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.
Re: [R] idiom for constructing data frame
I got rid of the extra column.
data.frame(r=seq(8), foo=NA, bar=NA, row.names=r)
Rich
On Tue, Mar 31, 2015 at 6:18 PM, Sven E. Templer sven.temp...@gmail.com wrote:
If you don't mind an extra column, you could use something similar to:
data.frame(r=seq(8),foo=NA,bar=NA)
If you do, here is another approach (see function body):
empty.frame - function (r = 1, n = 1, fill = NA_real_) {
data.frame(setNames(lapply(rep(fill, length(n)), rep, times=r), n))
}
empty.frame()
empty.frame(, seq(3))
empty.frame(8, c(foo, bar))
I could not put it in one line either, without retyping at least one
argument (n in this case).
So I suggest a function is the way to go for a simplified syntax ...
Thanks to all for the ideas!
Sven
On 31 March 2015 at 20:55, William Dunlap wdun...@tibco.com wrote:
You can use structure() to attach the names to a list that is input to
data.frame.
E.g.,
dfNames - c(First, Second Name)
data.frame(lapply(structure(dfNames, names=dfNames),
function(name)rep(NA_real_, 5)))
Bill Dunlap
TIBCO Software
wdunlap tibco.com
On Tue, Mar 31, 2015 at 11:37 AM, Sarah Goslee sarah.gos...@gmail.com
wrote:
Hi,
Duncan Murdoch suggested:
The matrix() function has a dimnames argument, so you could do this:
names - c(strat, id, pid)
data.frame(matrix(NA, nrow=10, ncol=3, dimnames=list(NULL, names)))
That's a definite improvement, thanks. But no way to skip matrix()? It
just seems unRlike, although since it's only full of NA values there
are no coercion issues with column types or anything, so it doesn't
hurt. It's just inelegant. :)
Sarah
--
Sarah Goslee
http://www.functionaldiversity.org
__
R-help@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.
[[alternative HTML version deleted]]
__
R-help@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.
[[alternative HTML version deleted]]
__
R-help@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@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.
Re: [R] idiom for constructing data frame
I've got dataFrame() in R.utils for this purpose, e.g.
df - dataFrame(colClasses=c(a=integer, b=double, c=character),
nrow=10L)
str(df)
'data.frame': 10 obs. of 3 variables:
$ a: int 0 0 0 0 0 0 0 0 0 0
$ b: num 0 0 0 0 0 0 0 0 0 0
$ c: chr ...
Related: You can use the colClasses() function to generate the
'colClasses' argument dynamically, e.g.
cols - colClasses(idc)
names(cols) - c(a, b, c)
str(cols)
Named chr [1:3] integer double character
- attr(*, names)= chr [1:3] a b c
cols - colClasses(sprintf(c2d%di, 4))
df - dataFrame(colClasses=cols, nrow=10L)
str(df)
'data.frame': 10 obs. of 7 variables:
$ : chr ...
$ : num 0 0 0 0 0 0 0 0 0 0
$ : num 0 0 0 0 0 0 0 0 0 0
$ : int 0 0 0 0 0 0 0 0 0 0
$ : int 0 0 0 0 0 0 0 0 0 0
$ : int 0 0 0 0 0 0 0 0 0 0
$ : int 0 0 0 0 0 0 0 0 0 0
dataFrame() is basically implemented as:
dataFrame - function(colClasses, nrow=1L, ...) {
df - vector(list, length=length(colClasses))
names(df) - names(colClasses)
for (kk in seq(along=df)) {
df[[kk]] - vector(colClasses[kk], length=nrow)
}
attr(df, row.names) - seq(length=nrow)
class(df) - data.frame
df
} # dataFrame()
/Henrik
On Tue, Mar 31, 2015 at 4:42 PM, Sarah Goslee sarah.gos...@gmail.com wrote:
On Tue, Mar 31, 2015 at 6:35 PM, Richard M. Heiberger r...@temple.edu wrote:
I got rid of the extra column.
data.frame(r=seq(8), foo=NA, bar=NA, row.names=r)
Brilliant!
After much fussing, including a disturbing detour into nested lapply
statements from which I barely emerged with my sanity (arguable, I
suppose), here is a one-liner that creates a data frame of arbitrary
number of rows given an existing data frame as template for column
number and name:
n - 8
df1 - data.frame(A=runif(9), B=runif(9))
do.call(data.frame, setNames(c(list(seq(n), r), as.list(rep(NA,
ncol(df1, c(r, row.names, colnames(df1
It's not elegant, but it is fairly R-ish. I should probably stop
hunting for an elegant solution now.
Thanks, everyone!
Sarah
Rich
On Tue, Mar 31, 2015 at 6:18 PM, Sven E. Templer sven.temp...@gmail.com
wrote:
If you don't mind an extra column, you could use something similar to:
data.frame(r=seq(8),foo=NA,bar=NA)
If you do, here is another approach (see function body):
empty.frame - function (r = 1, n = 1, fill = NA_real_) {
data.frame(setNames(lapply(rep(fill, length(n)), rep, times=r), n))
}
empty.frame()
empty.frame(, seq(3))
empty.frame(8, c(foo, bar))
I could not put it in one line either, without retyping at least one
argument (n in this case).
So I suggest a function is the way to go for a simplified syntax ...
Thanks to all for the ideas!
Sven
On 31 March 2015 at 20:55, William Dunlap wdun...@tibco.com wrote:
You can use structure() to attach the names to a list that is input to
data.frame.
E.g.,
dfNames - c(First, Second Name)
data.frame(lapply(structure(dfNames, names=dfNames),
function(name)rep(NA_real_, 5)))
Bill Dunlap
TIBCO Software
wdunlap tibco.com
On Tue, Mar 31, 2015 at 11:37 AM, Sarah Goslee sarah.gos...@gmail.com
wrote:
Hi,
Duncan Murdoch suggested:
The matrix() function has a dimnames argument, so you could do this:
names - c(strat, id, pid)
data.frame(matrix(NA, nrow=10, ncol=3, dimnames=list(NULL, names)))
That's a definite improvement, thanks. But no way to skip matrix()? It
just seems unRlike, although since it's only full of NA values there
are no coercion issues with column types or anything, so it doesn't
hurt. It's just inelegant. :)
Sarah
--
Sarah Goslee
http://www.functionaldiversity.org
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