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Li, Yan (IED)

2007-Oct-18 14:38 UTC

[R] How to avoid conversion to factors (data frame to zoo)

Hi all,

I was trying to convert a data frame to a zoo object so I can use some
time series functions like lag(). But it seems then everything became a
factor, so I have to convert it back to numeric to run the correct
regressions. Is there a way to avoid it? Here is an example:

#############################
a <- data.frame(nn =as.character(c("a", "b",
"c", "d")), dd as.Date("2007-08-01")+ c(1,2,3,4),
x = rnorm(4), y = rnorm(4))
a
str(a)


b <- zoo(a, order.by = a$dd)
b
str(b)

c <- data.frame(b)
str(c)

#############################################333
Results of this example:> a  nn         dd      x      y
1  a 2007-08-02  0.388 -0.394
2  b 2007-08-03 -0.054 -0.059
3  c 2007-08-04 -1.377  1.100
4  d 2007-08-05 -0.415  0.763> str(a)'data.frame':   4 obs. of  4 variables:
 $ nn: Factor w/ 4 levels
"a","b","c","d": 1 2 3 4
 $ dd:Class 'Date'  num [1:4] 13727 13728 13729 13730
 $ x : num   0.3877 -0.0538 -1.3771 -0.4150
 $ y : num  -0.3943 -0.0593  1.1000  0.7632> b <- zoo(a, order.by = a$dd)
> b           nn dd         x      y     
2007-08-02 a  2007-08-02  0.388 -0.394
2007-08-03 b  2007-08-03 -0.054 -0.059
2007-08-04 c  2007-08-04 -1.377  1.100
2007-08-05 d  2007-08-05 -0.415  0.763> str(b) chr [1:4, 1:4] "a" "b" "c" "d"
"2007-08-02" "2007-08-03" ...
 - attr(*, "dimnames")=List of 2
  ..$ : chr [1:4] "1" "2" "3" "4"
  ..$ : chr [1:4] "nn" "dd" "x" "y"
 - attr(*, "index")=Class 'Date'  num [1:4] 13727 13728 13729
13730> 
> c <- data.frame(b)
> str(c)'data.frame':   4 obs. of  4 variables:
 $ nn: Factor w/ 4 levels
"a","b","c","d": 1 2 3 4
  ..- attr(*, "names")= chr  "1" "2" "3"
"4"
 $ dd: Factor w/ 4 levels "2007-08-02","2007-08-03",..: 1 2
3 4
  ..- attr(*, "names")= chr  "1" "2" "3"
"4"
 $ x : Factor w/ 4 levels " 0.388","-0.054",..: 1 2 4 3
  ..- attr(*, "names")= chr  "1" "2" "3"
"4"
 $ y : Factor w/ 4 levels " 0.763"," 1.100",..: 4 3 2 1
  ..- attr(*, "names")= chr  "1" "2" "3"
"4"
##################################3
So after converting to zoo, all the variables became factors. How can I
keep this from happening? Thank you very much for any advice.

Yan
--------------------------------------------------------

This is not an offer (or solicitation of an offer) to bu...{{dropped:22}}

Gabor Grothendieck

2007-Oct-18 15:16 UTC

head link

[R] How to avoid conversion to factors (data frame to zoo)

A zoo variable is a vector or matrix with an index so you can't
mix types (factors and numeric) in a single zoo variable; however,
you can represented the factor numerically:

library(zoo)
set.seed(1)
a <- data.frame(
	nn = letters[1:4],
	dd = as.Date("2007-08-01") + 1:4,
	x = rnorm(4),
	y = rnorm(4)
)

z <- zoo(data.matrix(a[-2]), a$dd)
z


# or you can put the factor in a second zoo variable:

z2 <- zoo(as.matrix(a[3:4]), a$dd)
zf <- zoo(a$nn, a$dd)
z2
zf



On 10/18/07, Li, Yan (IED) <Yan.Y.Li at morganstanley.com>
wrote:> Hi all,
>
> I was trying to convert a data frame to a zoo object so I can use some
> time series functions like lag(). But it seems then everything became a
> factor, so I have to convert it back to numeric to run the correct
> regressions. Is there a way to avoid it? Here is an example:
>
> #############################
> a <- data.frame(nn =as.character(c("a", "b",
"c", "d")), dd > as.Date("2007-08-01")+
c(1,2,3,4), x = rnorm(4), y = rnorm(4))
> a
> str(a)
>
>
> b <- zoo(a, order.by = a$dd)
> b
> str(b)
>
> c <- data.frame(b)
> str(c)
>
> #############################################333
> Results of this example:
> > a
>  nn         dd      x      y
> 1  a 2007-08-02  0.388 -0.394
> 2  b 2007-08-03 -0.054 -0.059
> 3  c 2007-08-04 -1.377  1.100
> 4  d 2007-08-05 -0.415  0.763
> > str(a)
> 'data.frame':   4 obs. of  4 variables:
>  $ nn: Factor w/ 4 levels
"a","b","c","d": 1 2 3 4
>  $ dd:Class 'Date'  num [1:4] 13727 13728 13729 13730
>  $ x : num   0.3877 -0.0538 -1.3771 -0.4150
>  $ y : num  -0.3943 -0.0593  1.1000  0.7632
> > b <- zoo(a, order.by = a$dd)
> > b
>           nn dd         x      y
> 2007-08-02 a  2007-08-02  0.388 -0.394
> 2007-08-03 b  2007-08-03 -0.054 -0.059
> 2007-08-04 c  2007-08-04 -1.377  1.100
> 2007-08-05 d  2007-08-05 -0.415  0.763
> > str(b)
>  chr [1:4, 1:4] "a" "b" "c" "d"
"2007-08-02" "2007-08-03" ...
>  - attr(*, "dimnames")=List of 2
>  ..$ : chr [1:4] "1" "2" "3" "4"
>  ..$ : chr [1:4] "nn" "dd" "x" "y"
>  - attr(*, "index")=Class 'Date'  num [1:4] 13727 13728
13729 13730
> >
> > c <- data.frame(b)
> > str(c)
> 'data.frame':   4 obs. of  4 variables:
>  $ nn: Factor w/ 4 levels
"a","b","c","d": 1 2 3 4
>  ..- attr(*, "names")= chr  "1" "2"
"3" "4"
>  $ dd: Factor w/ 4 levels "2007-08-02","2007-08-03",..:
1 2 3 4
>  ..- attr(*, "names")= chr  "1" "2"
"3" "4"
>  $ x : Factor w/ 4 levels " 0.388","-0.054",..: 1 2 4 3
>  ..- attr(*, "names")= chr  "1" "2"
"3" "4"
>  $ y : Factor w/ 4 levels " 0.763"," 1.100",..: 4 3 2 1
>  ..- attr(*, "names")= chr  "1" "2"
"3" "4"
> ##################################3
> So after converting to zoo, all the variables became factors. How can I
> keep this from happening? Thank you very much for any advice.
>
> Yan
> --------------------------------------------------------
>
> This is not an offer (or solicitation of an offer) to bu...{{dropped:22}}
>
> ______________________________________________
> R-help at r-project.org mailing list
> 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.
>

John Kane

2007-Oct-18 15:21 UTC

head link

[R] How to avoid conversion to factors (data frame to zoo)

http://finzi.psych.upenn.edu/R/Rhelp02a/archive/98227.html

Your Rprofile has the setting
options(stringsAsFactors = TRUE)

If you override it globally  by using 

options(stringsAsFactors = FALSE) 

 it will give you what you want but observe Gabor's
caveat. I don't know of the other solution re settings
stringsAsFactors in the data.frame will work but it
looks like it should


--- "Li, Yan (IED)" <Yan.Y.Li at MorganStanley.com>
wrote:
> Hi all,
> 
> I was trying to convert a data frame to a zoo object
> so I can use some
> time series functions like lag(). But it seems then
> everything became a
> factor, so I have to convert it back to numeric to
> run the correct
> regressions. Is there a way to avoid it? Here is an
> example:
> 
> #############################
> a <- data.frame(nn =as.character(c("a", "b",
"c",
> "d")), dd > as.Date("2007-08-01")+ c(1,2,3,4), x =
rnorm(4), y > rnorm(4))
> a
> str(a)
> 
> 
> b <- zoo(a, order.by = a$dd)
> b
> str(b)
> 
> c <- data.frame(b)
> str(c)
> 
> #############################################333
> Results of this example:
> > a
>   nn         dd      x      y
> 1  a 2007-08-02  0.388 -0.394
> 2  b 2007-08-03 -0.054 -0.059
> 3  c 2007-08-04 -1.377  1.100
> 4  d 2007-08-05 -0.415  0.763
> > str(a)
> 'data.frame':   4 obs. of  4 variables:
>  $ nn: Factor w/ 4 levels
"a","b","c","d": 1 2 3 4
>  $ dd:Class 'Date'  num [1:4] 13727 13728 13729
> 13730
>  $ x : num   0.3877 -0.0538 -1.3771 -0.4150
>  $ y : num  -0.3943 -0.0593  1.1000  0.7632
> > b <- zoo(a, order.by = a$dd)
> > b
>            nn dd         x      y     
> 2007-08-02 a  2007-08-02  0.388 -0.394
> 2007-08-03 b  2007-08-03 -0.054 -0.059
> 2007-08-04 c  2007-08-04 -1.377  1.100
> 2007-08-05 d  2007-08-05 -0.415  0.763
> > str(b)
>  chr [1:4, 1:4] "a" "b" "c" "d"
"2007-08-02"
> "2007-08-03" ...
>  - attr(*, "dimnames")=List of 2
>   ..$ : chr [1:4] "1" "2" "3" "4"
>   ..$ : chr [1:4] "nn" "dd" "x" "y"
>  - attr(*, "index")=Class 'Date'  num [1:4] 13727
> 13728 13729 13730
> > 
> > c <- data.frame(b)
> > str(c)
> 'data.frame':   4 obs. of  4 variables:
>  $ nn: Factor w/ 4 levels
"a","b","c","d": 1 2 3 4
>   ..- attr(*, "names")= chr  "1" "2"
"3" "4"
>  $ dd: Factor w/ 4 levels
> "2007-08-02","2007-08-03",..: 1 2 3 4
>   ..- attr(*, "names")= chr  "1" "2"
"3" "4"
>  $ x : Factor w/ 4 levels " 0.388","-0.054",..: 1 2
> 4 3
>   ..- attr(*, "names")= chr  "1" "2"
"3" "4"
>  $ y : Factor w/ 4 levels " 0.763"," 1.100",..: 4 3
> 2 1
>   ..- attr(*, "names")= chr  "1" "2"
"3" "4"
> ##################################3
> So after converting to zoo, all the variables became
> factors. How can I
> keep this from happening? Thank you very much for
> any advice.
> 
> Yan
>
--------------------------------------------------------> 
> This is not an offer (or solicitation of an offer)
> to bu...{{dropped:22}}
> 
> ______________________________________________
> R-help at r-project.org mailing list
> 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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