[R] Merging variables

[PIKAL Petr]

Hi

Not sure if this is the most effective or general solution but

Here you get 2 if the value is same in both columns, 1 if it is only in one column and the other is NA and 0 if there is mismatch of values.
temp <- (ds_test[,2] %in% ds_test[,1])+(ds_test[,1] %in% ds_test[,2])

here you get 0 if the value is same or if there is mismatch, 1 if NA is in first column, 2 if it is in second and 3 if in both.
temp2 <- (is.na(ds_test[,2])+2*is.na(ds_test[,1]))

and with combination you get 1 if you want value from first column, 2 if from second, 4 if they are both NA, and -1 if there is mismatch.
temp2 + temp - 1

You could then construct ifelse command to select proper value.

Regards
Petr


> ds_test
  customer.x customer.y
1     Miller     Miller
2      Smith       <NA>
3       <NA>        Doe
4       Bird       Fish
5       <NA>       <NA>
> ds_test+temp
Error in FUN(left, right) : non-numeric argument to binary operator
> (is.na(ds_test[,1])+2*is.na(ds_test[,2]))+temp
[1] 2 3 2 0 5
> (is.na(ds_test[,1])+2*is.na(ds_test[,2]))+temp-2
[1]  0  1  0 -2  3
> (is.na(ds_test[,1])+2*is.na(ds_test[,2]))+temp-1
[1]  1  2  1 -1  4
> is.na(ds_test[,2])+2*is.na(ds_test[,1])
[1] 0 1 2 0 3
> (is.na(ds_test[,2])+2*is.na(ds_test[,1]))+temp-1
[1]  1  1  2 -1  4
> (is.na(ds_test[,2])+2*is.na(ds_test[,1]))+temp-1

> -----Original Message-----
> From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of
> G.Maubach at weinwolf.de
> Sent: Monday, June 6, 2016 2:30 PM
> To: r-help at r-project.org
> Subject: [R] Merging variables
>
> Hi All,
>
> I merged two datasets:
>
> ds_merge1 <- merge(x = ds_bw_customer_4_match, y =
> ds_zww_customer_4_match,
>   by.x = "customer", by.y = "customer",
>   all.x = TRUE, all.y = FALSE)
>
> R created a new dataset with the variables customer.x and customer.y. I
> would like to merge these two variable back together. I wrote a little function
> (code can be run) for it:
>
> -- cut --
>
> customer.x <- c("Miller", "Smith", NA,    "Bird", NA)
> customer.y <- c("Miller",  NA,     "Doe", "Fish", NA)
> ds_test <- data.frame(customer.x, customer.y, stringsAsFactors = FALSE)
>
> t_merge_variables <-
>   function(dataset,
>            var1,
>            var2,
>            merged_var) {
>
>     # Initialize
>     dataset[[merged_var]] = rep(NA, nrow(dataset))
>     dataset[["mismatch"]] = rep(NA, nrow(dataset))
>
>     for (i in 1:nrow(dataset)) {
>
>       # Check 1: var1 missing, var2 missing
>       if (is.na(dataset[[i, var1]]) &
>           is.na(dataset[[i, var2]])) {
>         dataset[["mismatch"]] <- 1  # var1 & var2 are missing
>
>       # Check 2: var1 filled, var2 missing
>       } else if (!is.na(dataset[[i, var1]]) &
>                  is.na(dataset[[i, var2]])) {
>         dataset[[i, merged_var]] <- dataset[[i, var1]]
>         dataset[["mismatch"]] <- 0
>
>       # Check 3: var1 missing, var2 filled
>       } else if (is.na(dataset[[i, var1]]) &
>                  !is.na(dataset[i, var2])) {
>         dataset[[i, merged_var]] <- dataset[[i, var2]]
>         dataset[["mismatch"]] <-  0
>
>       # Check 4: var1 == var2
>       } else if (dataset[[i, var1]] == dataset[[i, var2]]) {
>       dataset[[i, merged_var]] <- dataset[[i, var1]]
>       dataset[["mismatch"]] <- 0
>
>       # Leftover: var1 != var2
>       } else {
>         dataset[[i, merged_var]] <- NA
>         dataset[["mismatch"]] <- 2  # var1 != var2
>       }  # end if
>     }  # end for
>     return(dataset)
> }
>
> ds_var_merge1 <- t_merge_variables(dataset = ds_test,
>   var1 = "customer.x",
>   var2 = "customer.y",
>   merged_var = "customer")
>
> ds_var_merge1
>
> -- cut --
>
> It is executed without error but delivers the wrong values in the variable
> "mismatch". This variable is always 1 although it should be NA, 1 or 2
> respectively.
>
> Can you tell me why the variable is not correctly set?
>
> Kind regards
>
> Georg
>
> ______________________________________________
> 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.

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