[R] Loop

[Erik Iverson]

Hello,

The best way to get help from people on the list is
for you to give us *reproducible* examples of exactly
what is you want.

Usually, you can come up with some sample data and code
that corresponds to your situation, and that we can run
directly by cutting and pasting from the email.

You can find more details about this in the posting
guide, linked to at the bottom of every email.

Best,
--Erik

Matevž Pavlič wrote:
> Hi all,
> 
> I understand that you most of you this is a peice of cake but i am a
> complete newbie in this....so any example would be greatly
> aprpeciated and also any hint as how to get around in R. Frankly i
> sometimes see the help files kinda confusing.
> 
> M
> 
> -----Original Message----- From: Petr PIKAL
> [mailto:petr.pikal at precheza.cz] Sent: Thursday, November 04, 2010
> 3:40 PM To: Matevž Pavlič Cc: r-help at r-project.org Subject: Re: [R]
> Loop
> 
> Hi
> 
> r-help-bounces at r-project.org napsal dne 04.11.2010 14:21:38:
> 
>> Hi David,
>> 
>> I am still having troubles with that loop ...
>> 
>> This code gives me (kinda) the name of the column/field in a data
>> frame.
> Filed
>> names are form W1-W10. But there is a space between W and a number
>> -->
> "W 10",
>> and column (field) names do not contain numbers.
>> 
>>> for(i in 1:10) { vari <- paste("W",i) } vari
>> [1] "W 10"
>> 
>> Now as i understand than i would call different columns to R with
>> 
>>> w<-lit[[vari]]
>> Or am i wrong again?
>> 
>> Then I would probably need another loop to create the names of the
> variables
>> on R, i.e. w1 to w10. Is that a general idea for the procedure?
> 
> Beware of such loops. Instead of littering your workspace with
> files/objects constructed by some paste(whatever, i) solution you can
> save results in list or data.frame or matrix and simply use basic
> subsetting procedures or lapply/sapply functions.
> 
> I must say I never used such paste(...) construction yet and I work
> with R for quite a long time.
> 
> Regards Petr
> 
> 
>> 
>> Thank for the help, m
>> 
>> -----Original Message----- From: David Winsemius
>> [mailto:dwinsemius at comcast.net] Sent: Wednesday, November 03, 2010
>> 10:41 PM To: Matevž Pavlič Cc: r-help at r-project.org Subject: Re:
>> [R] Loop
>> 
>> 
>> On Nov 3, 2010, at 5:03 PM, Matevž Pavlič wrote:
>> 
>>> Hi,
>>> 
>>> Thanks for the help and the manuals. Will come very handy i am
>>> sure.
>>> 
>>> But regarding the code i don't hink this is what i
>>> want....basically i
> 
>>> would like to repeat bellow code :
>>> 
>>> w1<-table(lit$W1) w1<-as.data.frame(w1)
>> It appears you are not reading for meaning. Burns has advised you
>> how to
> 
>> construct column names and use them in your initial steps. The `$`
> function is
>> quite limited in comparison to `[[` , so he was showing you a
>> method
> that
>> would be more effective.  BTW the as.data.frame step is
>> unnecessary,
> since the
>> first thing write.table does is coerce an object to a data.frame.
>> The "write.table" name is misleading. It should be
>> "write.data.frame". You
> cannot
>> really write tables with write.table.
>> 
>> You would also use:
>> 
>> file=paste(vari, "csv", sep=".") as the file argument to
>> write.table
>> 
>>> write.table(w1,file="w1.csv",sep=";",row.names=T, dec=".")
>> What are these next actions supposed to do after the file is
>> written? Are you trying to store a group of related "w" objects
>> that will later
> be
>> indexed in sequence? If so, then a list would make more sense.
>> 
>> -- David.
>> 
>>> w1<- w1[order(w1$Freq, decreasing=TRUE),] w1<-head(w1, 20)
>>> 
>>> 20 times, where W1-20 (capital letters) are the fields in a 
>>> data.frame
> 
>>> called "lit" and w1-20 are the data.frames being created.
>>> 
>>> Hope that explains it better, m
>>> 
>>> -----Original Message----- From: Patrick Burns
>>> [mailto:pburns at pburns.seanet.com] Subject: Re: [R] Loop
>>> 
>>> If I understand properly, you'll want something like:
>>> 
>>> lit[["w2"]]
>>> 
>>> instead of
>>> 
>>> lit$w2
>>> 
>>> more accurately:
>>> 
>>> for(i in 1:20) { vari <- paste("w", i) lit[[vari]]
>>> 
>>> ... }
>>> 
>>> The two documents mentioned in my signature may help you.
>>> 
>>> On 03/11/2010 20:23, Matevž Pavlič wrote:
>>>> Hi all,
>>>> 
>>>> I managed to do what i want (with the great help of thi mailing
>>>>  list)  manually . Now i would like to automate it. I would
>>>> probably need a for loop for to help me with this...but of
>>>> course  I have no idea how to do that in R.  Bellow is the code
>>>> that i would like to be
> 
>>>> replicated for a number of times (let say 20). I would like to
>>>>  achieve  that w1 would change to w2, w3, w4 ... up to w20 and
>>>> by that
> 
>>>> create 20 data.frames that I would than bind together with
>>>> cbind.
>>>> 
>>>> (i did it like shown bellow -manually)
>>>> 
>>>> w1<-table(lit$W1) w1<-as.data.frame(w1) 
>>>> write.table(w1,file="w1.csv",sep=";",row.names=T, dec=".") w1<-
>>>> w1[order(w1$Freq, decreasing=TRUE),] w1<-head(w1, 20)
>>>> 
>>>> w2<-table(lit$W2)
>>>> 
>>>> w2<-as.data.frame(w2)
>>>> 
>>>> write.table(w2,file="w2.csv",sep=";",row.names=T, dec=".")
>>>> 
>>>> w2<- w2[order(w2$Freq, decreasing=TRUE),]
>>>> 
>>>> w2<-head(w2, 20) . . .
>>>> 
>>>> Thanks for the help,m
>> David Winsemius, MD West Hartford, CT
>> 
>> ______________________________________________ R-help at 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 at 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.