# [R] if else statement in loop

PIKAL Petr petr.pikal at precheza.cz
Mon Sep 29 14:18:59 CEST 2014

```Hi

Still cloudy, still errors.

> for(i in length(1:(nrow(X)))){
+     Y\$IID1new <- ifelse((as.character(Y[,2]) == as.character(X[,i]) &
+ Y\$IID1new != ''), as.character(as.matrix(X[,(nrow(X)+i)])),'')
+ }
Error in `\$<-.data.frame`(`*tmp*`, "IID1new", value = logical(0)) :
replacement has 0 rows, data has 3

You need first to add column IID1new to your Y data frame to use this piece of code. After that no errors from the code

However I wonder why the result shall be like this? What is the logic behind this.

>
> FID IID IID1new
> FAM01 samas4 samas4_father
> FAM01 samas5 samas5_mother
> FAM01 samas6 samas6_sibling

The only pattern I can see is that in first row (Y) you want item from column V4 (X), in second from V5 and in third you wan item from column V6. Is it always true? Or the pattern can change in following rows.

Based on your explanation you want to fill a column in Y from some column of X based on rownumber of Z?

For your special case it is like this.

Y\$IID1new<-diag(as.matrix(X[,4:6]))

Anyway, it seems to me that you want some kind of

?merge

Regards
Petr

Here are data I use for your code.

> dput(X)
structure(list(V1 = structure(c(1L, 1L, 1L), .Label = "samas4", class = "factor"),
V2 = structure(c(1L, 1L, 1L), .Label = "samas5", class = "factor"),
V3 = structure(c(1L, 1L, 1L), .Label = "samas6", class = "factor"),
V4 = structure(c(1L, 1L, 1L), .Label = "samas4_father", class = "factor"),
V5 = structure(c(1L, 1L, 1L), .Label = "samas5_mother", class = "factor"),
V6 = structure(c(1L, 1L, 1L), .Label = "samas6_sibling", class = "factor")), .Names = c("V1",
"V2", "V3", "V4", "V5", "V6"), class = "data.frame", row.names = c(NA,
-3L))
> dput(Y)
structure(list(FID = structure(c(1L, 1L, 1L), .Label = "FAM01", class = "factor"),
IID = structure(1:3, .Label = c("samas4", "samas5", "samas6"
), class = "factor")), .Names = c("FID", "IID"), class = "data.frame", row.names = c(NA,
-3L))

> -----Original Message-----
> From: Kate Ignatius [mailto:kate.ignatius at gmail.com]
> Sent: Monday, September 29, 2014 12:54 PM
> To: PIKAL Petr
> Cc: r-help
> Subject: Re: [R] if else statement in loop
>
> Ooops,
>
> I edited the code wrong to make it more easier for interpretation and
> got X and Y's mixed up.  Try this:
>
> for(i in length(1:(nrow(X)))){
>     Y\$IID1new <- ifelse((as.character(Y[,2]) == as.character(X[,i]) &
> Y\$IID1new != ''), as.character(as.matrix(X[,(nrow(X)+i)])),'')
> }
>
> The second should be like this:
>
> Y\$IID1new <- ifelse((as.character(Y[,2]) == as.character(X[,1])),
> as.character(as.matrix(X[,(nrow(X)+1)])),'')
>
> for(i in length(2:(nrow(X)))){
> ifelse((as.character(Y[,i]) == as.character(X[,i])),
> Y\$IID1new[is.na(Y\$IID1new)] <-
> as.character(as.matrix(X[,(nrow(X)+i)])),'')
> }
>
> The reason why I'm selecting for number of rows seems a little odd
> here I know but in real life this actually relies on a third data
> frame, say Z, which for simplicity I didn't include here. But I only
> want to start looking at the Nth column after twice as many rows in Z.
> For instance, if Z has 4 rows, I want to  take values for IID1new
> starting from column 9 in X to make IID1new in Y. Does that make
> sense? Will this cause a problem?
>
> So maybe it will probably be more like this if there were a Z
>
> for(i in length(1:(2*nrow(Z)))){
>     Y\$IID1new <- ifelse((as.character(Y[,2]) == as.character(X[,i]) &
> Y\$IID1new != ''), as.character(as.matrix(X[,(2*nrow(Z)+i)])),'')
> }
>
> But essentially what I would like is this:
>
> FID IID IID1new
> FAM01 samas4 samas4_father
> FAM01 samas5 samas5_mother
> FAM01 samas6 samas6_sibling
>
> I hope this is a little clearer...
>
> Let me know if there are more errors.
>
> K.
>
> On Mon, Sep 29, 2014 at 2:39 AM, PIKAL Petr <petr.pikal at precheza.cz>
> wrote:
> > Hi
> >
> > Please, be more clear in what do you want. I get many errors trying
> >
> >> for(i in length(1:(2*nrow(X)))){
> > +     Y\$IID1new <- ifelse((as.character(Y[,2]) == as.characterXl[,i])
> & X\$IID1new != '') , as.character(as.matrix(X[,(2*nrow(X)+i)])),'')
> > Error: unexpected ',' in:
> > "for(i in length(1:(2*nrow(X)))){
> >     Y\$IID1new <- ifelse((as.character(Y[,2]) == as.characterXl[,i]) &
> X\$IID1new != '') ,"
> >> }
> > Error: unexpected '}' in "}"
> >> for(i in length(1:(2*nrow(X)))){
> > +     Y\$IID1new <- ifelse((as.character(Y[,2]) == as.characterXl[,i])
> &
> > + X\$IID1new != '') , as.character(as.matrix(X[,(2*nrow(X)+i)])),'')
> > Error: unexpected ',' in:
> > "    Y\$IID1new <- ifelse((as.character(Y[,2]) == as.characterXl[,i])
> &
> > X\$IID1new != '') ,"
> >> }
> >
> >
> > Beside, this column X\$IID1new != '' does not exist in X
> >
> > Here you clearly ask for nonexistent column, and why the heck you
> want to select column by number of rows?
> >
> >> as.character(as.matrix(X[,(2*nrow(X)+1)]))
> > Error in `[.data.frame`(X, , (2 * nrow(X) + 1)) :
> >   undefined columns selected
> >
> > So based on your toy data frames, what shall be the result after your
> computation.
> >
> > Regards
> > Petr
> >
> >
> >> -----Original Message-----
> >> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> >> project.org] On Behalf Of Kate Ignatius
> >> Sent: Sunday, September 28, 2014 9:14 PM
> >> To: r-help
> >> Subject: [R] if else statement in loop
> >>
> >> I have two data frames
> >>
> >> For simplicity:
> >>
> >> X=
> >>
> >> V1 V2 V3  V4 V5 V6
> >> samas4 samas5 samas6 samas4_father samas5_mother samas6_sibling
> >> samas4 samas5 samas6 samas4_father samas5_mother samas6_sibling
> >> samas4 samas5 samas6 samas4_father samas5_mother samas6_sibling
> >>
> >> Y=
> >>
> >> FID IID
> >> FAM01 samas4
> >> FAM01 samas5
> >> FAM01 samas6
> >>
> >> I want to set to create a new IID in Y using V4 V5 V6 in X using an
> >> ifelse statement in a loop.  I've used something like the following
> >> (after figuring out my factor problem):
> >>
> >> for(i in length(1:(2*nrow(X)))){
> >>     Y\$IID1new <- ifelse((as.character(Y[,2]) == as.characterXl[,i])
> &
> >> X\$IID1new != '') , as.character(as.matrix(X[,(2*nrow(X)+i)])),'')
> >> }
> >>
> >> But of course this tends to overwrite.
> >>
> >> Is there an easy way to set up a loop to replace missing values?
> This
> >> didn't work either but not sure if its as easy as this:
> >>
> >> Y\$IID1new <- ifelse((as.character(Y[,2]) == as.characterXl[,i]) &
> >> X\$IID1new != '') , as.character(as.matrix(X[,(2*nrow(X)+i)])),'')
> >>
> >> for(i in length(2:(2*nrow(X)))){
> >> ifelse((as.character(Y[,i]) == as.character(Xl[,i])),
> >> X[is.na(X\$IID1new)] <- as.character(as.matrix(X[(2*nrow(X)+i)])),'')
> >> }
> >>
> >> Thanks!
> >>
> >> K.
> >>
> >> ______________________________________________
> >> R-help at r-project.org mailing list
> >> https://stat.ethz.ch/mailman/listinfo/r-help
> >> guide.html
> >> and provide commented, minimal, self-contained, reproducible code.
> >
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________________________________
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Nejste-li zamýšleným adresátem tohoto emailu, nejste oprávněni tento email jakkoliv užívat, rozšiřovat, kopírovat či zveřejňovat.
Odesílatel e-mailu neodpovídá za eventuální škodu způsobenou modifikacemi či zpožděním přenosu e-mailu.

V případě, že je tento e-mail součástí obchodního jednání:
- vyhrazuje si odesílatel právo ukončit kdykoliv jednání o uzavření smlouvy, a to z jakéhokoliv důvodu i bez uvedení důvodu.
- a obsahuje-li nabídku, je adresát oprávněn nabídku bezodkladně přijmout; Odesílatel tohoto e-mailu (nabídky) vylučuje přijetí nabídky ze strany příjemce s dodatkem či odchylkou.
- trvá odesílatel na tom, že příslušná smlouva je uzavřena teprve výslovným dosažením shody na všech jejích náležitostech.
- odesílatel tohoto emailu informuje, že není oprávněn uzavírat za společnost žádné smlouvy s výjimkou případů, kdy k tomu byl písemně zmocněn nebo písemně pověřen a takové pověření nebo plná moc byly adresátovi tohoto emailu případně osobě, kterou adresát zastupuje, předloženy nebo jejich existence je adresátovi či osobě jím zastoupené známá.

This e-mail and any documents attached to it may be confidential and are intended only for its intended recipients.
If you received this e-mail by mistake, please immediately inform its sender. Delete the contents of this e-mail with all attachments and its copies from your system.
If you are not the intended recipient of this e-mail, you are not authorized to use, disseminate, copy or disclose this e-mail in any manner.
The sender of this e-mail shall not be liable for any possible damage caused by modifications of the e-mail or by delay with transfer of the email.

In case that this e-mail forms part of business dealings:
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- if the e-mail contains an offer, the recipient is entitled to immediately accept such offer; The sender of this e-mail (offer) excludes any acceptance of the offer on the part of the recipient containing any amendment or variation.
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