[R] Merging variables

[PIKAL Petr]

Hi Michael

it is simple

set.seed(111)
let=sample(letters[1:10],6, replace=T)
dat1<-data.frame(let=let, customer=sample(1:10,6, replace=T))
let=sample(letters[1:10],6, replace=T)
dat2<-data.frame(let=let, customer=sample(1:10,6, replace=T))
merge(dat1, dat2, by.x="let", by.y="let", all=T)

Of course you could add customer variable to by parameter but sometimes it is necessary to leave it out. When you have two sets of analytical results and you have 2 variables operator but you want to merge those sets e.g. by date/hour of analysis.

Regards
Petr

> -----Original Message-----
> From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of Michael
> Dewey
> Sent: Monday, June 6, 2016 3:46 PM
> To: G.Maubach at weinwolf.de; r-help at r-project.org
> Subject: Re: [R] Merging variables
>
> X-Originating-<%= hostname %>-IP: [217.155.205.190]
>
> Dear Georg
>
> I find it a bit surprising that you end up with customer.x and customer.y. Can
> you share with us a toy example of two data.frames which exhibit this
> behaviour?
>
> On 06/06/2016 13:29, G.Maubach at weinwolf.de wrote:
> > 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.
> >
>
> --
> Michael
> http://www.dewey.myzen.co.uk/home.html
>
> ______________________________________________
> 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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