Re: [R] Apply function to one specific column / Alternative to for loop
Hi, Try: indx - grep(Test,test_df[,1]) ##assuming that there is some pattern res - within(test_df[-indx,],titel - rep(test_df$titel[indx], diff(c(indx,nrow(test_df)+1))-1)) ## If you need to change the class res[] - lapply(res,function(x) if(any(grepl([[:alpha:]],x))) as.character(x) else as.numeric(as.character(x))) ##Using data.frame(cbind()), etc. creates A.K. This option worked great for me! I knew there was a nicer and much faster way to solve this. One thing I already learned about R: Never use for-loops, there is always a better way :-) -- View this message in context: http://r.789695.n4.nabble.com/Apply-function-to-one-specific-column-Alternative-to-for-loop-tp4680566p4680621.html Sent from the R help mailing list archive at Nabble.com. __ R-help@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.
Re: [R] Apply function to one specific column / Alternative to for loop
This might be of some use :
http://nsaunders.wordpress.com/2010/08/20/a-brief-introduction-to-apply-in-r/
Umair Durrani
email: umairdurr...@outlook.com
Date: Sat, 16 Nov 2013 07:30:29 -0800
From: ron...@gmx.net
To: r-help@r-project.org
Subject: [R] Apply function to one specific column / Alternative to for loop
Hi guys, I am a total newbie to R, so I hope this isn't a totally dumb
question. I have a dataframe with a title in one row and the corresponding
values in the next rows. Let's take this example:
test_df - data.frame(cbind(titel = , x = 4:5, y = 1:2))
test_df = rbind(cbind(titel=1.Test, x=, y=), test_df,
cbind(titel=2.Test, x=, y=), test_df, cbind(titel=3.Test, x=,
y=), test_df)
test_df
titel x y
1 1.Test
24 1
35 2
4 2.Test
54 1
65 2
7 3.Test
84 1
95 2
What I want to have is:
titel x y
2 1.Test 4 1
3 1.Test 5 2
5 2.Test 4 1
6 2.Test 5 2
8 3.Test 4 1
9 3.Test 5 2
In my example, the title is in every third line, but in my real data there
is no pattern. Each title has at least one line but can have x lines.
I was able to solve my problem in a for loop with the following code:
test_df$titel - as.character(test_df$titel)
for (i in 1:nrow(test_df))
{
if (nchar(test_df$titel[i])==0){
test_df$titel[i]=test_df$titel[i-1]
}
}
test_df - subset(test_df,test_df$x!=)
The problem is, I have a lot of data and the for loop is obviously very
slow. Is there a more elegant way to achieve the same? I think I have to use
the apply function, but I don't know how to use it with just one column.
--
View this message in context:
http://r.789695.n4.nabble.com/Apply-function-to-one-specific-column-Alternative-to-for-loop-tp4680566.html
Sent from the R help mailing list archive at Nabble.com.
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Re: [R] Apply function to one specific column / Alternative to for loop
Hi,
Try:
indx - grep(Test,test_df[,1]) ##assuming that there is some pattern
res - within(test_df[-indx,],titel - rep(test_df$titel[indx],
diff(c(indx,nrow(test_df)+1))-1))
## If you need to change the class
res[] - lapply(res,function(x) if(any(grepl([[:alpha:]],x))) as.character(x)
else as.numeric(as.character(x)))
##Using data.frame(cbind()), etc. creates
A.K.
On Saturday, November 16, 2013 11:14 AM, Stageexp ron...@gmx.net wrote:
Hi guys, I am a total newbie to R, so I hope this isn't a totally dumb
question. I have a dataframe with a title in one row and the corresponding
values in the next rows. Let's take this example:
test_df - data.frame(cbind(titel = , x = 4:5, y = 1:2))
test_df = rbind(cbind(titel=1.Test, x=, y=), test_df,
cbind(titel=2.Test, x=, y=), test_df, cbind(titel=3.Test, x=,
y=), test_df)
test_df
titel x y
1 1.Test
2 4 1
3 5 2
4 2.Test
5 4 1
6 5 2
7 3.Test
8 4 1
9 5 2
What I want to have is:
titel x y
2 1.Test 4 1
3 1.Test 5 2
5 2.Test 4 1
6 2.Test 5 2
8 3.Test 4 1
9 3.Test 5 2
In my example, the title is in every third line, but in my real data there
is no pattern. Each title has at least one line but can have x lines.
I was able to solve my problem in a for loop with the following code:
test_df$titel - as.character(test_df$titel)
for (i in 1:nrow(test_df))
{
if (nchar(test_df$titel[i])==0){
test_df$titel[i]=test_df$titel[i-1]
}
}
test_df - subset(test_df,test_df$x!=)
The problem is, I have a lot of data and the for loop is obviously very
slow. Is there a more elegant way to achieve the same? I think I have to use
the apply function, but I don't know how to use it with just one column.
--
View this message in context:
http://r.789695.n4.nabble.com/Apply-function-to-one-specific-column-Alternative-to-for-loop-tp4680566.html
Sent from the R help mailing list archive at Nabble.com.
__
R-help@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.
__
R-help@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.
