Re: [R] Erase content of dataframe in a single stroke
Variations on the same theme: > testdf<-data.frame(A=c(1,2),B=c(2,3),C=c(3,4)) > testdf[0,] [1] A B C <0 rows> (or 0-length row.names) > testdf[FALSE,] [1] A B C <0 rows> (or 0-length row.names) > testdf[integer(0),] [1] A B C <0 rows> (or 0-length row.names) > testdf[NULL,] [1] A B C <0 rows> (or 0-length row.names) -pd > On 27 Sep 2018, at 10:32 , PIKAL Petr wrote: > > Hm > > I would use > >> testdf<-data.frame(A=c(1,2),B=c(2,3),C=c(3,4)) >> str(testdf) > 'data.frame': 2 obs. of 3 variables: > $ A: num 1 2 > $ B: num 2 3 > $ C: num 3 4 >> testdf<-testdf[-(1:nrow(testdf)),] >> str(testdf) > 'data.frame': 0 obs. of 3 variables: > $ A: num > $ B: num > $ C: num > > Cheers > Petr > >> -Original Message- >> From: R-help On Behalf Of Jim Lemon >> Sent: Thursday, September 27, 2018 10:12 AM >> To: Luigi Marongiu ; r-help mailing list > project.org> >> Subject: Re: [R] Erase content of dataframe in a single stroke >> >> Ah, yes, try 'as.data.frame" on it. >> >> Jim >> >> On Thu, Sep 27, 2018 at 6:00 PM Luigi Marongiu >> wrote: >>> >>> Thank you Jim, >>> this requires the definition of an ad hoc function; strange that R >>> does not have a function for this purpose... >>> Anyway, it works but it changes the structure of the data. By >>> redefining the dataframe as I did, I obtain: >>> >>>> df >>> [1] A B C >>> <0 rows> (or 0-length row.names) >>>> str(df) >>> 'data.frame': 0 obs. of 3 variables: >>> $ A: num >>> $ B: num >>> $ C: num >>> >>> When applying your function, I get: >>> >>>> df >>> $A >>> NULL >>> >>> $B >>> NULL >>> >>> $C >>> NULL >>> >>>> str(df) >>> List of 3 >>> $ A: NULL >>> $ B: NULL >>> $ C: NULL >>> >>> The dataframe has become a list. Would that affect downstream >> applications? >>> >>> Thank you, >>> Luigi >>> On Thu, Sep 27, 2018 at 9:45 AM Jim Lemon >> wrote: >>>> >>>> Hi Luigi, >>>> Maybe this: >>>> >>>> testdf<-data.frame(A=1,B=2,C=3) >>>>> testdf >>>> A B C >>>> 1 1 2 3 >>>> toNull<-function(x) return(NULL) >>>> testdf<-sapply(testdf,toNull) >>>> >>>> Jim >>>> On Thu, Sep 27, 2018 at 5:29 PM Luigi Marongiu >> wrote: >>>>> >>>>> Dear all, >>>>> I would like to erase the content of a dataframe -- but not the >>>>> dataframe itself -- in a simple and fast way. >>>>> At the moment I do that by re-defining the dataframe itself in this way: >>>>> >>>>>> df <- data.frame(A = numeric(), >>>>> + B = numeric(), >>>>> + C = character()) >>>>>> # assign >>>>>> A <- 5 >>>>>> B <- 0.6 >>>>>> C <- 103 >>>>>> # load >>>>>> R <- cbind(A, B, C) >>>>>> df <- rbind(df, R) >>>>>> df >>>>> A B C >>>>> 1 5 0.6 103 >>>>>> # erase >>>>>> df <- data.frame(A = numeric(), >>>>> + B = numeric(), >>>>> + C = character()) >>>>>> df >>>>> [1] A B C >>>>> <0 rows> (or 0-length row.names) >>>>>> >>>>> >>>>> Is there a way to erase the content of the dataframe in a simplier >>>>> (acting on all the dataframe at once instead of naming each column >>>>> individually) and nicer (with a specific erasure command instead >>>>> of re-defyining the object itself) way? >>>>> >>>>> Thank you. >>>>> -- >>>>> Best regards, >>>>> Luigi >>>>> >>>>> __ >>>>> 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,
Re: [R] Erase content of dataframe in a single stroke
Hi Luigi,
Actually I doubt that the original problem you try to solve requires the
initialization of an empty data.frame with a particular structure.
However, if you think you really need this step, I would write a
function for it and also consider edge cases.
getSkeleton <- function(x, drop_levels = FALSE) {
out <- x[numeric(0L), , drop = FALSE]
if (isTRUE(drop_levels)) out <- droplevels(out)
out
}
Note that it retains or drops factor levels depending on 'drop_levels'.
It only matters if you have factors in your data.frame.
'drop = FALSE' is required to guard against silent conversion to a
vector if 'x' has only one column.
Regards,
Denes
On 09/27/2018 11:11 AM, Jan van der Laan wrote:
Or
testdf <- testdf[FALSE, ]
or
testdf <- testdf[numeric(0), ]
which seems to be slightly faster.
Best,
Jan
Op 27-9-2018 om 10:32 schreef PIKAL Petr:
Hm
I would use
testdf<-data.frame(A=c(1,2),B=c(2,3),C=c(3,4))
str(testdf)
'data.frame': 2 obs. of 3 variables:
$ A: num 1 2
$ B: num 2 3
$ C: num 3 4
testdf<-testdf[-(1:nrow(testdf)),]
str(testdf)
'data.frame': 0 obs. of 3 variables:
$ A: num
$ B: num
$ C: num
Cheers
Petr
-Original Message-
From: R-help On Behalf Of Jim Lemon
Sent: Thursday, September 27, 2018 10:12 AM
To: Luigi Marongiu ; r-help mailing list
project.org>
Subject: Re: [R] Erase content of dataframe in a single stroke
Ah, yes, try 'as.data.frame" on it.
Jim
On Thu, Sep 27, 2018 at 6:00 PM Luigi Marongiu
wrote:
Thank you Jim,
this requires the definition of an ad hoc function; strange that R
does not have a function for this purpose...
Anyway, it works but it changes the structure of the data. By
redefining the dataframe as I did, I obtain:
df
[1] A B C
<0 rows> (or 0-length row.names)
str(df)
'data.frame': 0 obs. of 3 variables:
$ A: num
$ B: num
$ C: num
When applying your function, I get:
df
$A
NULL
$B
NULL
$C
NULL
str(df)
List of 3
$ A: NULL
$ B: NULL
$ C: NULL
The dataframe has become a list. Would that affect downstream
applications?
Thank you,
Luigi
On Thu, Sep 27, 2018 at 9:45 AM Jim Lemon
wrote:
Hi Luigi,
Maybe this:
testdf<-data.frame(A=1,B=2,C=3)
testdf
A B C
1 1 2 3
toNull<-function(x) return(NULL)
testdf<-sapply(testdf,toNull)
Jim
On Thu, Sep 27, 2018 at 5:29 PM Luigi Marongiu
wrote:
Dear all,
I would like to erase the content of a dataframe -- but not the
dataframe itself -- in a simple and fast way.
At the moment I do that by re-defining the dataframe itself in
this way:
df <- data.frame(A = numeric(),
+ B = numeric(),
+ C = character())
# assign
A <- 5
B <- 0.6
C <- 103
# load
R <- cbind(A, B, C)
df <- rbind(df, R)
df
A B C
1 5 0.6 103
# erase
df <- data.frame(A = numeric(),
+ B = numeric(),
+ C = character())
df
[1] A B C
<0 rows> (or 0-length row.names)
Is there a way to erase the content of the dataframe in a simplier
(acting on all the dataframe at once instead of naming each column
individually) and nicer (with a specific erasure command instead
of re-defyining the object itself) way?
Thank you.
--
Best regards,
Luigi
__
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.
--
Best regards,
Luigi
__
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.
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Re: [R] Erase content of dataframe in a single stroke
Or testdf <- testdf[FALSE, ] or testdf <- testdf[numeric(0), ] which seems to be slightly faster. Best, Jan Op 27-9-2018 om 10:32 schreef PIKAL Petr: Hm I would use testdf<-data.frame(A=c(1,2),B=c(2,3),C=c(3,4)) str(testdf) 'data.frame': 2 obs. of 3 variables: $ A: num 1 2 $ B: num 2 3 $ C: num 3 4 testdf<-testdf[-(1:nrow(testdf)),] str(testdf) 'data.frame': 0 obs. of 3 variables: $ A: num $ B: num $ C: num Cheers Petr -Original Message- From: R-help On Behalf Of Jim Lemon Sent: Thursday, September 27, 2018 10:12 AM To: Luigi Marongiu ; r-help mailing list Subject: Re: [R] Erase content of dataframe in a single stroke Ah, yes, try 'as.data.frame" on it. Jim On Thu, Sep 27, 2018 at 6:00 PM Luigi Marongiu wrote: Thank you Jim, this requires the definition of an ad hoc function; strange that R does not have a function for this purpose... Anyway, it works but it changes the structure of the data. By redefining the dataframe as I did, I obtain: df [1] A B C <0 rows> (or 0-length row.names) str(df) 'data.frame': 0 obs. of 3 variables: $ A: num $ B: num $ C: num When applying your function, I get: df $A NULL $B NULL $C NULL str(df) List of 3 $ A: NULL $ B: NULL $ C: NULL The dataframe has become a list. Would that affect downstream applications? Thank you, Luigi On Thu, Sep 27, 2018 at 9:45 AM Jim Lemon wrote: Hi Luigi, Maybe this: testdf<-data.frame(A=1,B=2,C=3) testdf A B C 1 1 2 3 toNull<-function(x) return(NULL) testdf<-sapply(testdf,toNull) Jim On Thu, Sep 27, 2018 at 5:29 PM Luigi Marongiu wrote: Dear all, I would like to erase the content of a dataframe -- but not the dataframe itself -- in a simple and fast way. At the moment I do that by re-defining the dataframe itself in this way: df <- data.frame(A = numeric(), + B = numeric(), + C = character()) # assign A <- 5 B <- 0.6 C <- 103 # load R <- cbind(A, B, C) df <- rbind(df, R) df A B C 1 5 0.6 103 # erase df <- data.frame(A = numeric(), + B = numeric(), + C = character()) df [1] A B C <0 rows> (or 0-length row.names) Is there a way to erase the content of the dataframe in a simplier (acting on all the dataframe at once instead of naming each column individually) and nicer (with a specific erasure command instead of re-defyining the object itself) way? Thank you. -- Best regards, Luigi __ 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. -- Best regards, Luigi __ 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. Osobní údaje: Informace o zpracování a ochraně osobních údajů obchodních partnerů PRECHEZA a.s. jsou zveřejněny na: https://www.precheza.cz/zasady-ochrany-osobnich-udaju/ | Information about processing and protection of business partner’s personal data are available on website: https://www.precheza.cz/en/personal-data-protection-principles/ Důvěrnost: Tento e-mail a jakékoliv k němu připojené dokumenty jsou důvěrné a podléhají tomuto právně závaznému prohláąení o vyloučení odpovědnosti: https://www.precheza.cz/01-dovetek/ | This email and any documents attached to it may be confidential and are subject to the legally binding disclaimer: https://www.precheza.cz/en/01-disclaimer/ __ 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] Erase content of dataframe in a single stroke
You're right. Apparently one can form a list with NULL elements but not a data frame. I just saw Petr's answer, which seems to do the trick. Jim On Thu, Sep 27, 2018 at 6:19 PM Luigi Marongiu wrote: > > I am not sure if I got it right; Now I get: > > > toNull<-function(x) return(NULL) > > df<-as.data.frame(sapply(df,toNull)) > > df > data frame with 0 columns and 0 rows > > str(df) > 'data.frame': 0 obs. of 0 variables > On Thu, Sep 27, 2018 at 10:12 AM Jim Lemon wrote: > > > > Ah, yes, try 'as.data.frame" on it. > > > > Jim > > > > On Thu, Sep 27, 2018 at 6:00 PM Luigi Marongiu > > wrote: > > > > > > Thank you Jim, > > > this requires the definition of an ad hoc function; strange that R > > > does not have a function for this purpose... > > > Anyway, it works but it changes the structure of the data. By > > > redefining the dataframe as I did, I obtain: > > > > > > > df > > > [1] A B C > > > <0 rows> (or 0-length row.names) > > > > str(df) > > > 'data.frame': 0 obs. of 3 variables: > > > $ A: num > > > $ B: num > > > $ C: num > > > > > > When applying your function, I get: > > > > > > > df > > > $A > > > NULL > > > > > > $B > > > NULL > > > > > > $C > > > NULL > > > > > > > str(df) > > > List of 3 > > > $ A: NULL > > > $ B: NULL > > > $ C: NULL > > > > > > The dataframe has become a list. Would that affect downstream > > > applications? > > > > > > Thank you, > > > Luigi > > > On Thu, Sep 27, 2018 at 9:45 AM Jim Lemon wrote: > > > > > > > > Hi Luigi, > > > > Maybe this: > > > > > > > > testdf<-data.frame(A=1,B=2,C=3) > > > > > testdf > > > > A B C > > > > 1 1 2 3 > > > > toNull<-function(x) return(NULL) > > > > testdf<-sapply(testdf,toNull) > > > > > > > > Jim > > > > On Thu, Sep 27, 2018 at 5:29 PM Luigi Marongiu > > > > wrote: > > > > > > > > > > Dear all, > > > > > I would like to erase the content of a dataframe -- but not the > > > > > dataframe itself -- in a simple and fast way. > > > > > At the moment I do that by re-defining the dataframe itself in this > > > > > way: > > > > > > > > > > > df <- data.frame(A = numeric(), > > > > > + B = numeric(), > > > > > + C = character()) > > > > > > # assign > > > > > > A <- 5 > > > > > > B <- 0.6 > > > > > > C <- 103 > > > > > > # load > > > > > > R <- cbind(A, B, C) > > > > > > df <- rbind(df, R) > > > > > > df > > > > > A B C > > > > > 1 5 0.6 103 > > > > > > # erase > > > > > > df <- data.frame(A = numeric(), > > > > > + B = numeric(), > > > > > + C = character()) > > > > > > df > > > > > [1] A B C > > > > > <0 rows> (or 0-length row.names) > > > > > > > > > > > > > > > > Is there a way to erase the content of the dataframe in a simplier > > > > > (acting on all the dataframe at once instead of naming each column > > > > > individually) and nicer (with a specific erasure command instead of > > > > > re-defyining the object itself) way? > > > > > > > > > > Thank you. > > > > > -- > > > > > Best regards, > > > > > Luigi > > > > > > > > > > __ > > > > > 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. > > > > > > > > > > > > -- > > > Best regards, > > > Luigi > > > > -- > Best regards, > Luigi __ 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] Erase content of dataframe in a single stroke
Hm I would use > testdf<-data.frame(A=c(1,2),B=c(2,3),C=c(3,4)) > str(testdf) 'data.frame': 2 obs. of 3 variables: $ A: num 1 2 $ B: num 2 3 $ C: num 3 4 > testdf<-testdf[-(1:nrow(testdf)),] > str(testdf) 'data.frame': 0 obs. of 3 variables: $ A: num $ B: num $ C: num Cheers Petr > -Original Message- > From: R-help On Behalf Of Jim Lemon > Sent: Thursday, September 27, 2018 10:12 AM > To: Luigi Marongiu ; r-help mailing list project.org> > Subject: Re: [R] Erase content of dataframe in a single stroke > > Ah, yes, try 'as.data.frame" on it. > > Jim > > On Thu, Sep 27, 2018 at 6:00 PM Luigi Marongiu > wrote: > > > > Thank you Jim, > > this requires the definition of an ad hoc function; strange that R > > does not have a function for this purpose... > > Anyway, it works but it changes the structure of the data. By > > redefining the dataframe as I did, I obtain: > > > > > df > > [1] A B C > > <0 rows> (or 0-length row.names) > > > str(df) > > 'data.frame': 0 obs. of 3 variables: > > $ A: num > > $ B: num > > $ C: num > > > > When applying your function, I get: > > > > > df > > $A > > NULL > > > > $B > > NULL > > > > $C > > NULL > > > > > str(df) > > List of 3 > > $ A: NULL > > $ B: NULL > > $ C: NULL > > > > The dataframe has become a list. Would that affect downstream > applications? > > > > Thank you, > > Luigi > > On Thu, Sep 27, 2018 at 9:45 AM Jim Lemon > wrote: > > > > > > Hi Luigi, > > > Maybe this: > > > > > > testdf<-data.frame(A=1,B=2,C=3) > > > > testdf > > > A B C > > > 1 1 2 3 > > > toNull<-function(x) return(NULL) > > > testdf<-sapply(testdf,toNull) > > > > > > Jim > > > On Thu, Sep 27, 2018 at 5:29 PM Luigi Marongiu > wrote: > > > > > > > > Dear all, > > > > I would like to erase the content of a dataframe -- but not the > > > > dataframe itself -- in a simple and fast way. > > > > At the moment I do that by re-defining the dataframe itself in this way: > > > > > > > > > df <- data.frame(A = numeric(), > > > > + B = numeric(), > > > > + C = character()) > > > > > # assign > > > > > A <- 5 > > > > > B <- 0.6 > > > > > C <- 103 > > > > > # load > > > > > R <- cbind(A, B, C) > > > > > df <- rbind(df, R) > > > > > df > > > > A B C > > > > 1 5 0.6 103 > > > > > # erase > > > > > df <- data.frame(A = numeric(), > > > > + B = numeric(), > > > > + C = character()) > > > > > df > > > > [1] A B C > > > > <0 rows> (or 0-length row.names) > > > > > > > > > > > > > Is there a way to erase the content of the dataframe in a simplier > > > > (acting on all the dataframe at once instead of naming each column > > > > individually) and nicer (with a specific erasure command instead > > > > of re-defyining the object itself) way? > > > > > > > > Thank you. > > > > -- > > > > Best regards, > > > > Luigi > > > > > > > > __ > > > > 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. > > > > > > > > -- > > Best regards, > > Luigi > > __ > 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. Osobní údaje: Informace o zpracování a ochraně osobních údajů obchodních partnerů PRECHEZA a.s. jsou zveřejněny na: https://www.precheza.cz/zasady-ochrany-osobnich-udaju/ | Information about processing and protection of business partner’s personal data are available on website: https://www.precheza.cz/en/personal-data-protection-principles/ Důvěrnost: Tento e-mail a jakékoliv k němu připojené dokumenty jsou důvěrné a podléhají tomuto právně závaznému prohláąení o vyloučení odpovědnosti: https://www.precheza.cz/01-dovetek/ | This email and any documents attached to it may be confidential and are subject to the legally binding disclaimer: https://www.precheza.cz/en/01-disclaimer/ __ 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] Erase content of dataframe in a single stroke
Ah, yes, try 'as.data.frame" on it. Jim On Thu, Sep 27, 2018 at 6:00 PM Luigi Marongiu wrote: > > Thank you Jim, > this requires the definition of an ad hoc function; strange that R > does not have a function for this purpose... > Anyway, it works but it changes the structure of the data. By > redefining the dataframe as I did, I obtain: > > > df > [1] A B C > <0 rows> (or 0-length row.names) > > str(df) > 'data.frame': 0 obs. of 3 variables: > $ A: num > $ B: num > $ C: num > > When applying your function, I get: > > > df > $A > NULL > > $B > NULL > > $C > NULL > > > str(df) > List of 3 > $ A: NULL > $ B: NULL > $ C: NULL > > The dataframe has become a list. Would that affect downstream applications? > > Thank you, > Luigi > On Thu, Sep 27, 2018 at 9:45 AM Jim Lemon wrote: > > > > Hi Luigi, > > Maybe this: > > > > testdf<-data.frame(A=1,B=2,C=3) > > > testdf > > A B C > > 1 1 2 3 > > toNull<-function(x) return(NULL) > > testdf<-sapply(testdf,toNull) > > > > Jim > > On Thu, Sep 27, 2018 at 5:29 PM Luigi Marongiu > > wrote: > > > > > > Dear all, > > > I would like to erase the content of a dataframe -- but not the > > > dataframe itself -- in a simple and fast way. > > > At the moment I do that by re-defining the dataframe itself in this way: > > > > > > > df <- data.frame(A = numeric(), > > > + B = numeric(), > > > + C = character()) > > > > # assign > > > > A <- 5 > > > > B <- 0.6 > > > > C <- 103 > > > > # load > > > > R <- cbind(A, B, C) > > > > df <- rbind(df, R) > > > > df > > > A B C > > > 1 5 0.6 103 > > > > # erase > > > > df <- data.frame(A = numeric(), > > > + B = numeric(), > > > + C = character()) > > > > df > > > [1] A B C > > > <0 rows> (or 0-length row.names) > > > > > > > > > > Is there a way to erase the content of the dataframe in a simplier > > > (acting on all the dataframe at once instead of naming each column > > > individually) and nicer (with a specific erasure command instead of > > > re-defyining the object itself) way? > > > > > > Thank you. > > > -- > > > Best regards, > > > Luigi > > > > > > __ > > > 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. > > > > -- > Best regards, > Luigi __ 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] Erase content of dataframe in a single stroke
Hi Luigi, Maybe this: testdf<-data.frame(A=1,B=2,C=3) > testdf A B C 1 1 2 3 toNull<-function(x) return(NULL) testdf<-sapply(testdf,toNull) Jim On Thu, Sep 27, 2018 at 5:29 PM Luigi Marongiu wrote: > > Dear all, > I would like to erase the content of a dataframe -- but not the > dataframe itself -- in a simple and fast way. > At the moment I do that by re-defining the dataframe itself in this way: > > > df <- data.frame(A = numeric(), > + B = numeric(), > + C = character()) > > # assign > > A <- 5 > > B <- 0.6 > > C <- 103 > > # load > > R <- cbind(A, B, C) > > df <- rbind(df, R) > > df > A B C > 1 5 0.6 103 > > # erase > > df <- data.frame(A = numeric(), > + B = numeric(), > + C = character()) > > df > [1] A B C > <0 rows> (or 0-length row.names) > > > > Is there a way to erase the content of the dataframe in a simplier > (acting on all the dataframe at once instead of naming each column > individually) and nicer (with a specific erasure command instead of > re-defyining the object itself) way? > > Thank you. > -- > Best regards, > Luigi > > __ > 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.
[R] Erase content of dataframe in a single stroke
Dear all, I would like to erase the content of a dataframe -- but not the dataframe itself -- in a simple and fast way. At the moment I do that by re-defining the dataframe itself in this way: > df <- data.frame(A = numeric(), + B = numeric(), + C = character()) > # assign > A <- 5 > B <- 0.6 > C <- 103 > # load > R <- cbind(A, B, C) > df <- rbind(df, R) > df A B C 1 5 0.6 103 > # erase > df <- data.frame(A = numeric(), + B = numeric(), + C = character()) > df [1] A B C <0 rows> (or 0-length row.names) > Is there a way to erase the content of the dataframe in a simplier (acting on all the dataframe at once instead of naming each column individually) and nicer (with a specific erasure command instead of re-defyining the object itself) way? Thank you. -- Best regards, Luigi __ 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.
