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Fridolin

2012-Aug-27 10:09 UTC

[R] Changing entries of column of type "factor"/Adding a new level to a factor

What is a smart way to change an entry inside a column of a dataframe or
matrix which is of type "factor"?

Here is my script incl. input data:> #set working directory:
> setwd("K:/R")
> 
> #read in data:
> input<-read.table("Exampleinput.txt", sep="\t",
header=TRUE)
> 
> #check data:
> input   Ind      M1      M2      M3
1    1   96/98 120/120     0/0
2    2 102/108 120/124 305/305
3    3  96/108 120/120     0/0
4    4     0/0 116/120 300/305
5    5  96/108 120/130 300/305
6    6   98/98 116/120 300/305
7    7  98/108 120/120 305/305
8    8  98/108 120/120 305/305
9    9  98/102 120/124 300/300
10  10 108/108 120/120 305/305> str(input)'data.frame':	10 obs. of  4 variables:
 $ Ind: int  1 2 3 4 5 6 7 8 9 10
 $ M1 : Factor w/ 8 levels "0/0","102/108",..: 5 2 4 1 4 8 7
7 6 3
 $ M2 : Factor w/ 4 levels "116/120","120/120",..: 2 3 2 1 4
1 2 2 3 2
 $ M3 : Factor w/ 4 levels "0/0","300/300",..: 1 4 1 3 3 3 4
4 2 4> 
> #replace 0/0 by 999/999:
> for (r in 1:10)+   for (c in 2:4)
+     if (input[r,c]=="0/0") input[r,c]<-"999/999"
Warnmeldungen:
1: In `[<-.factor`(`*tmp*`, iseq, value = "999/999") :
  invalid factor level, NAs generated
2: In `[<-.factor`(`*tmp*`, iseq, value = "999/999") :
  invalid factor level, NAs generated
3: In `[<-.factor`(`*tmp*`, iseq, value = "999/999") :
  invalid factor level, NAs generated> input   Ind      M1      M2      M3
1    1   96/98 120/120    <NA>
2    2 102/108 120/124 305/305
3    3  96/108 120/120    <NA>
4    4    <NA> 116/120 300/305
5    5  96/108 120/130 300/305
6    6   98/98 116/120 300/305
7    7  98/108 120/120 305/305
8    8  98/108 120/120 305/305
9    9  98/102 120/124 300/300
10  10 108/108 120/120 305/305


I want to replace all "0/0" by "999/999". My code should
work for columns of
type "character" and "integer". But to make it work for a
"factor"-column I
would need to add the new level of "999/999" at first, I guess. How do
I add
a new level?



--
View this message in context:
http://r.789695.n4.nabble.com/Changing-entries-of-column-of-type-factor-Adding-a-new-level-to-a-factor-tp4641402.html
Sent from the R help mailing list archive at Nabble.com.

PIKAL Petr

2012-Aug-27 14:22 UTC

head link

[R] Changing entries of column of type "factor"/Adding a new level to a factor

Hi

you could save yourself time to read help page for factor
> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of Fridolin
> Sent: Monday, August 27, 2012 12:09 PM
> To: r-help at r-project.org
> Subject: [R] Changing entries of column of type "factor"/Adding a
new
> level to a factor
> 
> What is a smart way to change an entry inside a column of a dataframe
> or matrix which is of type "factor"?
data.frame is not a matrix

each factor have levels attribute
levels(input$M1)
level 0/0 shall be the first so
levels(input$M1)[1] <-"999/999"

Easiest way is probably cycle through columns of your data

for( i in columns)
levels(input[,i])[levels(input[,i])=="0/0"]<-"999/999"

Regards
Petr

> 
> Here is my script incl. input data:
> > #set working directory:
> > setwd("K:/R")
> >
> > #read in data:
> > input<-read.table("Exampleinput.txt", sep="\t",
header=TRUE)
> >
> > #check data:
> > input
>    Ind      M1      M2      M3
> 1    1   96/98 120/120     0/0
> 2    2 102/108 120/124 305/305
> 3    3  96/108 120/120     0/0
> 4    4     0/0 116/120 300/305
> 5    5  96/108 120/130 300/305
> 6    6   98/98 116/120 300/305
> 7    7  98/108 120/120 305/305
> 8    8  98/108 120/120 305/305
> 9    9  98/102 120/124 300/300
> 10  10 108/108 120/120 305/305
> > str(input)
> 'data.frame':	10 obs. of  4 variables:
>  $ Ind: int  1 2 3 4 5 6 7 8 9 10
>  $ M1 : Factor w/ 8 levels "0/0","102/108",..: 5 2 4 1
4 8 7 7 6 3  $
> M2 : Factor w/ 4 levels "116/120","120/120",..: 2 3 2 1
4 1 2 2 3 2  $
> M3 : Factor w/ 4 levels "0/0","300/300",..: 1 4 1 3 3 3
4 4 2 4
> >
> > #replace 0/0 by 999/999:
> > for (r in 1:10)
> +   for (c in 2:4)
> +     if (input[r,c]=="0/0") input[r,c]<-"999/999"
> Warnmeldungen:
> 1: In `[<-.factor`(`*tmp*`, iseq, value = "999/999") :
>   invalid factor level, NAs generated
> 2: In `[<-.factor`(`*tmp*`, iseq, value = "999/999") :
>   invalid factor level, NAs generated
> 3: In `[<-.factor`(`*tmp*`, iseq, value = "999/999") :
>   invalid factor level, NAs generated
> > input
>    Ind      M1      M2      M3
> 1    1   96/98 120/120    <NA>
> 2    2 102/108 120/124 305/305
> 3    3  96/108 120/120    <NA>
> 4    4    <NA> 116/120 300/305
> 5    5  96/108 120/130 300/305
> 6    6   98/98 116/120 300/305
> 7    7  98/108 120/120 305/305
> 8    8  98/108 120/120 305/305
> 9    9  98/102 120/124 300/300
> 10  10 108/108 120/120 305/305
> 
> 
> I want to replace all "0/0" by "999/999". My code
should work for
> columns of type "character" and "integer". But to make
it work for a
> "factor"-column I would need to add the new level of
"999/999" at
> first, I guess. How do I add a new level?
> 
> 
> 
> --
> View this message in context: http://r.789695.n4.nabble.com/Changing-
> entries-of-column-of-type-factor-Adding-a-new-level-to-a-factor-
> tp4641402.html
> Sent from the R help mailing list archive at Nabble.com.
> 
> ______________________________________________
> 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.

William Dunlap

2012-Aug-27 14:28 UTC

head link

[R] Changing entries of column of type "factor"/Adding a new level to a factor

One way is to read in your text data as character columns with
read.table(stringsAsFactors=FALSE,...), then fiddle with the values,
and finally make factors out of the columns that  you want to be factors,
specifying the levels explicitly.  (Do you really want those number/number
things to be treated as factors?  The orders of their levels will be weird
unless
you list them all when making the factor.)

Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com

> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at
r-project.org] On Behalf
> Of Fridolin
> Sent: Monday, August 27, 2012 3:09 AM
> To: r-help at r-project.org
> Subject: [R] Changing entries of column of type "factor"/Adding a
new level to a factor
> 
> What is a smart way to change an entry inside a column of a dataframe or
> matrix which is of type "factor"?
> 
> Here is my script incl. input data:
> > #set working directory:
> > setwd("K:/R")
> >
> > #read in data:
> > input<-read.table("Exampleinput.txt", sep="\t",
header=TRUE)
> >
> > #check data:
> > input
>    Ind      M1      M2      M3
> 1    1   96/98 120/120     0/0
> 2    2 102/108 120/124 305/305
> 3    3  96/108 120/120     0/0
> 4    4     0/0 116/120 300/305
> 5    5  96/108 120/130 300/305
> 6    6   98/98 116/120 300/305
> 7    7  98/108 120/120 305/305
> 8    8  98/108 120/120 305/305
> 9    9  98/102 120/124 300/300
> 10  10 108/108 120/120 305/305
> > str(input)
> 'data.frame':	10 obs. of  4 variables:
>  $ Ind: int  1 2 3 4 5 6 7 8 9 10
>  $ M1 : Factor w/ 8 levels "0/0","102/108",..: 5 2 4 1
4 8 7 7 6 3
>  $ M2 : Factor w/ 4 levels "116/120","120/120",..: 2 3
2 1 4 1 2 2 3 2
>  $ M3 : Factor w/ 4 levels "0/0","300/300",..: 1 4 1 3
3 3 4 4 2 4
> >
> > #replace 0/0 by 999/999:
> > for (r in 1:10)
> +   for (c in 2:4)
> +     if (input[r,c]=="0/0") input[r,c]<-"999/999"
> Warnmeldungen:
> 1: In `[<-.factor`(`*tmp*`, iseq, value = "999/999") :
>   invalid factor level, NAs generated
> 2: In `[<-.factor`(`*tmp*`, iseq, value = "999/999") :
>   invalid factor level, NAs generated
> 3: In `[<-.factor`(`*tmp*`, iseq, value = "999/999") :
>   invalid factor level, NAs generated
> > input
>    Ind      M1      M2      M3
> 1    1   96/98 120/120    <NA>
> 2    2 102/108 120/124 305/305
> 3    3  96/108 120/120    <NA>
> 4    4    <NA> 116/120 300/305
> 5    5  96/108 120/130 300/305
> 6    6   98/98 116/120 300/305
> 7    7  98/108 120/120 305/305
> 8    8  98/108 120/120 305/305
> 9    9  98/102 120/124 300/300
> 10  10 108/108 120/120 305/305
> 
> 
> I want to replace all "0/0" by "999/999". My code
should work for columns of
> type "character" and "integer". But to make it work for
a "factor"-column I
> would need to add the new level of "999/999" at first, I guess.
How do I add
> a new level?
> 
> 
> 
> --
> View this message in context:
http://r.789695.n4.nabble.com/Changing-entries-of-
> column-of-type-factor-Adding-a-new-level-to-a-factor-tp4641402.html
> Sent from the R help mailing list archive at Nabble.com.
> 
> ______________________________________________
> 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.

David Winsemius

2012-Aug-27 16:19 UTC

head link

[R] Changing entries of column of type "factor"/Adding a new level to a factor

On Aug 27, 2012, at 3:09 AM, Fridolin wrote:
> What is a smart way to change an entry inside a column of a  
> dataframe or
> matrix which is of type "factor"?
>
> Here is my script incl. input data:
>> #set working directory:
>> setwd("K:/R")
>>
>> #read in data:
>> input<-read.table("Exampleinput.txt", sep="\t",
header=TRUE)
>>
>> #check data:
>> input
>   Ind      M1      M2      M3
> 1    1   96/98 120/120     0/0
> 2    2 102/108 120/124 305/305
> 3    3  96/108 120/120     0/0
> 4    4     0/0 116/120 300/305
> 5    5  96/108 120/130 300/305
> 6    6   98/98 116/120 300/305
> 7    7  98/108 120/120 305/305
> 8    8  98/108 120/120 305/305
> 9    9  98/102 120/124 300/300
> 10  10 108/108 120/120 305/305
>> str(input)
> 'data.frame':	10 obs. of  4 variables:
> $ Ind: int  1 2 3 4 5 6 7 8 9 10
> $ M1 : Factor w/ 8 levels "0/0","102/108",..: 5 2 4 1 4
8 7 7 6 3
> $ M2 : Factor w/ 4 levels "116/120","120/120",..: 2 3 2
1 4 1 2 2 3 2
> $ M3 : Factor w/ 4 levels "0/0","300/300",..: 1 4 1 3 3
3 4 4 2 4
>>
>> #replace 0/0 by 999/999:
>> for (r in 1:10)
> +   for (c in 2:4)
> +     if (input[r,c]=="0/0") input[r,c]<-"999/999"
> Warnmeldungen:
> 1: In `[<-.factor`(`*tmp*`, iseq, value = "999/999") :
>  invalid factor level, NAs generated
> 2: In `[<-.factor`(`*tmp*`, iseq, value = "999/999") :
>  invalid factor level, NAs generated
> 3: In `[<-.factor`(`*tmp*`, iseq, value = "999/999") :
>  invalid factor level, NAs generated
>> input
>   Ind      M1      M2      M3
> 1    1   96/98 120/120    <NA>
> 2    2 102/108 120/124 305/305
> 3    3  96/108 120/120    <NA>
> 4    4    <NA> 116/120 300/305
> 5    5  96/108 120/130 300/305
> 6    6   98/98 116/120 300/305
> 7    7  98/108 120/120 305/305
> 8    8  98/108 120/120 305/305
> 9    9  98/102 120/124 300/300
> 10  10 108/108 120/120 305/305
>
>
> I want to replace all "0/0" by "999/999". My code
should work for
> columns of
> type "character" and "integer". But to make it work for
a "factor"-
> column I
> would need to add the new level of "999/999" at first, I guess.
How
> do I add
> a new level?
?levels

levels(input$M1) <- c(levels(input$M1), "999/999")

-- 

David Winsemius, MD
Heritage Laboratories
West Hartford, CT

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