Emmanuel Levy
2015-Jul-21 13:21 UTC
[R] combining columns into a "combination index" of the same length
Hi, The answer to this is probably straightforward, I have a dataframe and I'd like to build an index of column combinations, e.g. col1 col2 --> col3 (the index I need) A 1 1 A 1 1 A 2 2 B 1 3 B 2 4 B 2 4 At the moment I use: col3 <- apply(mat[,sel.col], 1, paste0) But I wonder if another approach could be faster? Thanks, Emmanuel [[alternative HTML version deleted]]
Thierry Onkelinx
2015-Jul-21 13:32 UTC
[R] combining columns into a "combination index" of the same length
Yes. paste0() can work on vectors. So paste0(mat[, col1], mat[, col2]) ir. Thierry Onkelinx Instituut voor natuur- en bosonderzoek / Research Institute for Nature and Forest team Biometrie & Kwaliteitszorg / team Biometrics & Quality Assurance Kliniekstraat 25 1070 Anderlecht Belgium To call in the statistician after the experiment is done may be no more than asking him to perform a post-mortem examination: he may be able to say what the experiment died of. ~ Sir Ronald Aylmer Fisher The plural of anecdote is not data. ~ Roger Brinner The combination of some data and an aching desire for an answer does not ensure that a reasonable answer can be extracted from a given body of data. ~ John Tukey 2015-07-21 15:21 GMT+02:00 Emmanuel Levy <emmanuel.levy at gmail.com>:> Hi, > > The answer to this is probably straightforward, I have a dataframe and I'd > like to build an index of column combinations, e.g. > > col1 col2 --> col3 (the index I need) > A 1 1 > A 1 1 > A 2 2 > B 1 3 > B 2 4 > B 2 4 > > > At the moment I use: > col3 <- apply(mat[,sel.col], 1, paste0) > > But I wonder if another approach could be faster? > > Thanks, > > Emmanuel > > [[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. >[[alternative HTML version deleted]]
Thierry Onkelinx
2015-Jul-21 14:00 UTC
[R] combining columns into a "combination index" of the same length
Please always keep the mailing list in cc.
If mat is a data.frame, then you can use do.call. Then the number of
columns doesn't matter.
do.call(paste, mtcars[, c("mpg", "cyl")])
do.call(paste, mtcars[, c("mpg", "cyl", "disp")])
do.call(paste, mtcars)
ir. Thierry Onkelinx
Instituut voor natuur- en bosonderzoek / Research Institute for Nature and
Forest
team Biometrie & Kwaliteitszorg / team Biometrics & Quality Assurance
Kliniekstraat 25
1070 Anderlecht
Belgium
To call in the statistician after the experiment is done may be no more
than asking him to perform a post-mortem examination: he may be able to say
what the experiment died of. ~ Sir Ronald Aylmer Fisher
The plural of anecdote is not data. ~ Roger Brinner
The combination of some data and an aching desire for an answer does not
ensure that a reasonable answer can be extracted from a given body of data.
~ John Tukey
2015-07-21 15:43 GMT+02:00 Emmanuel Levy <emmanuel.levy at gmail.com>:
> Thanks! -- this is indeed much faster (plus I made a mistake, one has to
> use paste with the option collapse="".
>
> The thing is I'm looking for a solution *without paste*. The reason is
> that* there may be two or more columns*.
>
>
>
> On 21 July 2015 at 16:32, Thierry Onkelinx <thierry.onkelinx at
inbo.be>
> wrote:
>
>> Yes. paste0() can work on vectors. So paste0(mat[, col1], mat[, col2])
>>
>> ir. Thierry Onkelinx
>> Instituut voor natuur- en bosonderzoek / Research Institute for Nature
>> and Forest
>> team Biometrie & Kwaliteitszorg / team Biometrics & Quality
Assurance
>> Kliniekstraat 25
>> 1070 Anderlecht
>> Belgium
>>
>> To call in the statistician after the experiment is done may be no more
>> than asking him to perform a post-mortem examination: he may be able to
say
>> what the experiment died of. ~ Sir Ronald Aylmer Fisher
>> The plural of anecdote is not data. ~ Roger Brinner
>> The combination of some data and an aching desire for an answer does
not
>> ensure that a reasonable answer can be extracted from a given body of
data.
>> ~ John Tukey
>>
>> 2015-07-21 15:21 GMT+02:00 Emmanuel Levy <emmanuel.levy at
gmail.com>:
>>
>>> Hi,
>>>
>>> The answer to this is probably straightforward, I have a dataframe
and
>>> I'd
>>> like to build an index of column combinations, e.g.
>>>
>>> col1 col2 --> col3 (the index I need)
>>> A 1 1
>>> A 1 1
>>> A 2 2
>>> B 1 3
>>> B 2 4
>>> B 2 4
>>>
>>>
>>> At the moment I use:
>>> col3 <- apply(mat[,sel.col], 1, paste0)
>>>
>>> But I wonder if another approach could be faster?
>>>
>>> Thanks,
>>>
>>> Emmanuel
>>>
>>> [[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.
>>>
>>
>>
>
[[alternative HTML version deleted]]
Emmanuel Levy
2015-Jul-21 15:01 UTC
[R] combining columns into a "combination index" of the same length
Thanks Thierry, you made my day :) On 21 July 2015 at 17:00, Thierry Onkelinx <thierry.onkelinx at inbo.be> wrote:> Please always keep the mailing list in cc. > > If mat is a data.frame, then you can use do.call. Then the number of > columns doesn't matter. > > do.call(paste, mtcars[, c("mpg", "cyl")]) > do.call(paste, mtcars[, c("mpg", "cyl", "disp")]) > do.call(paste, mtcars) > > > ir. Thierry Onkelinx > Instituut voor natuur- en bosonderzoek / Research Institute for Nature and > Forest > team Biometrie & Kwaliteitszorg / team Biometrics & Quality Assurance > Kliniekstraat 25 > 1070 Anderlecht > Belgium > > To call in the statistician after the experiment is done may be no more > than asking him to perform a post-mortem examination: he may be able to say > what the experiment died of. ~ Sir Ronald Aylmer Fisher > The plural of anecdote is not data. ~ Roger Brinner > The combination of some data and an aching desire for an answer does not > ensure that a reasonable answer can be extracted from a given body of data. > ~ John Tukey > > 2015-07-21 15:43 GMT+02:00 Emmanuel Levy <emmanuel.levy at gmail.com>: > >> Thanks! -- this is indeed much faster (plus I made a mistake, one has to >> use paste with the option collapse="". >> >> The thing is I'm looking for a solution *without paste*. The reason is >> that* there may be two or more columns*. >> >> >> >> On 21 July 2015 at 16:32, Thierry Onkelinx <thierry.onkelinx at inbo.be> >> wrote: >> >>> Yes. paste0() can work on vectors. So paste0(mat[, col1], mat[, col2]) >>> >>> ir. Thierry Onkelinx >>> Instituut voor natuur- en bosonderzoek / Research Institute for Nature >>> and Forest >>> team Biometrie & Kwaliteitszorg / team Biometrics & Quality Assurance >>> Kliniekstraat 25 >>> 1070 Anderlecht >>> Belgium >>> >>> To call in the statistician after the experiment is done may be no more >>> than asking him to perform a post-mortem examination: he may be able to say >>> what the experiment died of. ~ Sir Ronald Aylmer Fisher >>> The plural of anecdote is not data. ~ Roger Brinner >>> The combination of some data and an aching desire for an answer does not >>> ensure that a reasonable answer can be extracted from a given body of data. >>> ~ John Tukey >>> >>> 2015-07-21 15:21 GMT+02:00 Emmanuel Levy <emmanuel.levy at gmail.com>: >>> >>>> Hi, >>>> >>>> The answer to this is probably straightforward, I have a dataframe and >>>> I'd >>>> like to build an index of column combinations, e.g. >>>> >>>> col1 col2 --> col3 (the index I need) >>>> A 1 1 >>>> A 1 1 >>>> A 2 2 >>>> B 1 3 >>>> B 2 4 >>>> B 2 4 >>>> >>>> >>>> At the moment I use: >>>> col3 <- apply(mat[,sel.col], 1, paste0) >>>> >>>> But I wonder if another approach could be faster? >>>> >>>> Thanks, >>>> >>>> Emmanuel >>>> >>>> [[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. >>>> >>> >>> >> >[[alternative HTML version deleted]]