[R] create function for compare two dataframe.

PIKAL Petr petr.pikal at precheza.cz
Mon Feb 29 10:15:57 CET 2016


Hi

You does not need to create function, you can use functions already available.

> s1<- read.table("clipboard", header=T, sep=",")
> s2<- read.table("clipboard", sep=",")

You presented second table without names.
> names(s2) <- names(s1)

> s1
     ID VAL1 VAL2 VAL3
1   ID1    2    2    3
2   ID2    0    3    3
3   ID3    0    2    4
> s2
     ID VAL1 VAL2 VAL3
1   ID1    0    2    3
2   ID2    0    2    3
3   ID3    0    2    2

You need to add a column in which you specify data frame and merge them
> s1$dat<-"df1"
> s2$dat<-"df2"
> s<-merge(s1,s2, all=T)

Now you need to reshape your data

> library(reshape2)

> s.m<-melt(s)
Using ID, dat as id variables
> s.m
      ID dat variable value
1    ID1 df1     VAL1     2
2    ID2 df2     VAL1     0
3    ID2 df1     VAL1     0
4    ID3 df2     VAL1     0
5    ID3 df1     VAL1     0
6    ID1 df2     VAL1     0
7    ID1 df1     VAL2     2
8    ID2 df2     VAL2     2
9    ID2 df1     VAL2     3
10   ID3 df2     VAL2     2
11   ID3 df1     VAL2     2
12   ID1 df2     VAL2     2
13   ID1 df1     VAL3     3
14   ID2 df2     VAL3     3
15   ID2 df1     VAL3     3
16   ID3 df2     VAL3     2
17   ID3 df1     VAL3     4
18   ID1 df2     VAL3     3

And cast the new structure.
> dcast(s.m, ID+variable~dat)
      ID variable df1 df2
1    ID1     VAL1   2  NA
2    ID1     VAL2   2  NA
3    ID1     VAL3   3  NA
4    ID2     VAL1   0   0
5    ID2     VAL2   3   2
6    ID2     VAL3   3   3
7    ID3     VAL1   0   0
8    ID3     VAL2   2   2
9    ID3     VAL3   4   2
10   ID1     VAL1  NA   0
11   ID1     VAL2  NA   2
12   ID1     VAL3  NA   3

This was the point that I was rather surprised but I found a reason. Your ID variable does not have 3 but four values - although ID1 looks the same, in one there is an extra space, therefore you have different ID1 in s1 from ID1 in s2.

That is why it is recommended to use dput() for exchanging data with others.

> str(s)
'data.frame':   6 obs. of  5 variables:
 $ ID  : Factor w/ 4 levels "  ID1","  ID2",..: 1 2 2 3 3 4
 $ VAL1: int  2 0 0 0 0 0
 $ VAL2: int  2 2 3 2 2 2
 $ VAL3: int  3 3 3 2 4 3
 $ dat : chr  "df1" "df2" "df1" "df2" ...

> s1$ID
[1]   ID1   ID2   ID3
Levels:   ID1   ID2   ID3
> s2$ID
[1] ID1     ID2   ID3
Levels:   ID2   ID3 ID1

> str(s1)
'data.frame':   3 obs. of  5 variables:
 $ ID  : Factor w/ 3 levels "  ID1","  ID2",..: 1 2 3
 $ VAL1: int  2 0 0
 $ VAL2: int  2 3 2
 $ VAL3: int  3 3 4
 $ dat : chr  "df1" "df1" "df1"
> str(s2)
'data.frame':   3 obs. of  5 variables:
 $ ID  : Factor w/ 3 levels "  ID2","  ID3",..: 3 1 2
 $ VAL1: int  0 0 0
 $ VAL2: int  2 2 2
 $ VAL3: int  3 3 2
 $ dat : chr  "df2" "df2" "df2"
>

Cheers
Petr


> -----Original Message-----
> From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of
> Hiroyuki Sato
> Sent: Monday, February 29, 2016 9:44 AM
> To: r-help at r-project.org
> Subject: [R] create function for compare two dataframe.
>
> Hello
>
> I would like to create a funciton which is create new dataframe for
> compare reslut of two dataframes.
>
>   No.  COLUMN DF1  DF2
>   "1"  "VAL1" "2"  "0" # <- compare ID1,VAL1
>   "2"  "VAL2" "3"  "2" # <- comapre ID2,VAL2
>   "3"  "VAL3" "4"  "2" # <- compare ID3,VAL3
>
> s1 <- read.table("sample1.txt",header=T,sep=',')
> s2 <- read.table("sample2.txt",header=T,sep=',')
> comp_data(df1,df2)
>
> sample1.txt
>   ID,VAL1,VAL2,VAL3
>   ID1,2,2,3
>   ID2,0,3,3
>   ID3,0,2,4
>
> sample2.txt
>   ID1,0,2,3
>   ID2,0,2,3
>   ID3,0,2,2
>
> I created the functions, but I got the following error.
> Could you tell me how to add new frame data?
> Or alternative way?
>
>   1: In `[<-.factor`(`*tmp*`, ri, value = "3") :
>     invalid factor level, NA generated
>   2: In `[<-.factor`(`*tmp*`, ri, value = "VAL3") :
>     invalid factor level, NA generated
>   3: In `[<-.factor`(`*tmp*`, ri, value = "4") :
>     invalid factor level, NA generated
>
>
>
>   comp_data <- function(df1,df2) {
>     #
>     # create null data.frame
>     out <- data.frame(matrix(rep(NA,4),nrow=1))[numeric(0), ]
>     colnames(out) <- c("ID","Site","df1","df2")
>
>     # column names
>     col_names <- colnames(df1)
>
>     # col_size
>     col_size <- ncol(df1)
>     row_size <- nrow(df1)
>
>     for( col in 2:col_size ){
>       for( row in 1:row_size ){
>         if( df1[row,col] != df2[row,col] ){
>           out <-
> rbind(out,c(df1[row,1],col_names[col],df1[row,col],df2[row,col]))
>         }
>       }
>     }
>     out
>   }
>
> Best regards.
>
>       [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
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> PLEASE do read the posting guide http://www.R-project.org/posting-
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> and provide commented, minimal, self-contained, reproducible code.

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