Hi, I am pretty new to R and I would apreciatte very much your help to
solve my problem. I have 40 csv files that have the same structure, and I
want to merge them into a single data frame.
I already have load and combined all the cvs files into a large list, and I
created two
filenames <- list.files('data',full.names=TRUE)
All_data <- lapply(filenames,function(i){
###read cvs files and add the row and column names to each data frame###
read.csv(i, header=FALSE, sep = "", col.names = col_names, row.names
row_names)
})
However I would like to sum the rows of cvs files to get a single data
frame (each cvs file has 47 rows and colunms, so the final data frame
should have the same). I could only do it one by one data data frame, but I
was wondering if anyone could give an idea of how to write a function for
this.
Thanks,
Alejandra
[[alternative HTML version deleted]]
Alejandra Lopez-Galan <alejandra7galan at gmail.com> writes: Hello, I'm not sure to fully answer you question but I'll give it a try. I'll use the library "data.table" as I forgot how to do it in base R. If you don't have it you will have to install it by doing> install.packages(data.table,repos ="http://cran.us.r-project.org")let's say you have this list of data.frame> lapply(1:2,function(x) data.frame(B=letters[1:10],A=rnorm(10)))## [[1]] ## B A ## 1 a 1.8276026 ## 2 b 0.2870562 ## 3 c -0.6304431 ## 4 d 0.3066375 ## 5 e 0.3274438 ## 6 f 0.3370640 ## 7 g -1.6660051 ## 8 h -0.3736336 ## 9 i 0.1494459 ## 10 j -1.0036616 ## [[2]] ## B A ## 1 a -1.1488812 ## 2 b -0.4423796 ## 3 c -0.2690834 ## 4 d -1.1390742 ## 5 e 0.7142574 ## 6 f 0.3316523 ## 7 g 0.3187546 ## 8 h 0.1099996 ## 9 i 0.3972000 ## 10 j 0.4749161 and want to sum the A column for each data.frame then you can use the following: # Assign the list to the variable aa aa <- lapply(1:2,function(x) data.table(B=letters[1:10],A=rnorm(10))) then:> >lapply(aa,function(x) data.table(x)[,sum(A)])## [[1]] ## [1] 6.533179 ## [[2]] ## [1] 2.075677 Notice that I converted the each data.frame to a data.table and then sum the column A. If you want to bind the resutls together you can do do.call(rbind,lapply(aa,function(x) data.table(x)[,sum(A)])) [,1] [1,] -9.377476 [2,] -3.853971 HTH, Best Regards, Jeremie> Hi, I am pretty new to R and I would apreciatte very much your help to > solve my problem. I have 40 csv files that have the same structure, and I > want to merge them into a single data frame. > > I already have load and combined all the cvs files into a large list, and I > created two > > filenames <- list.files('data',full.names=TRUE) > > All_data <- lapply(filenames,function(i){ > ###read cvs files and add the row and column names to each data frame### > read.csv(i, header=FALSE, sep = "", col.names = col_names, row.names > row_names) > }) > > However I would like to sum the rows of cvs files to get a single data > frame (each cvs file has 47 rows and colunms, so the final data frame > should have the same). I could only do it one by one data data frame, but I > was wondering if anyone could give an idea of how to write a function for > this. > > Thanks, > Alejandra > > [[alternative HTML version deleted]] > > ______________________________________________ > 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.
Hi see in line> -----Original Message----- > From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of Alejandra > Lopez-Galan > Sent: Monday, January 15, 2018 10:29 AM > To: r-help at r-project.org > Subject: [R] sum multiple csv files > > Hi, I am pretty new to R and I would apreciatte very much your help to solve > my problem. I have 40 csv files that have the same structure, and I want to > merge them into a single data frame. > > I already have load and combined all the cvs files into a large list, and I created > two > > filenames <- list.files('data',full.names=TRUE) > > All_data <- lapply(filenames,function(i){ > ###read cvs files and add the row and column names to each data frame### > read.csv(i, header=FALSE, sep = "", col.names = col_names, row.names > row_names) > }) > > However I would like to sum the rows of cvs files to get a single data frame > (each cvs file has 47 rows and colunms, so the final data frame should have the > same). I could only do it one by one data data frame, but I was wondering ifAnd here I am rather lost. The only possible solution (to me) is to sum all values in first row of file 1, 2, 3, ... In that case probably the easiest way is to change list to array aaa<-array(unlist(All_data), dim=c(47,47, 40)) result <- apply(aaa,1:2,sum) Example: lll <- structure(list(A = structure(list(V1 = 1:3, V2 = 4:6, V3 = 7:9, V4 = 10:12), .Names = c("V1", "V2", "V3", "V4"), row.names = c(NA, -3L), class = "data.frame"), B = structure(list(V1 = 1:3, V2 = 4:6, V3 = 7:9, V4 = 10:12), .Names = c("V1", "V2", "V3", "V4"), row.names = c(NA, -3L), class = "data.frame")), .Names = c("A", "B"))> aaa<-array(unlist(lll), dim=c(3,4,2)) > aaa, , 1 [,1] [,2] [,3] [,4] [1,] 1 4 7 10 [2,] 2 5 8 11 [3,] 3 6 9 12 , , 2 [,1] [,2] [,3] [,4] [1,] 1 4 7 10 [2,] 2 5 8 11 [3,] 3 6 9 12> apply(aaa,1:2,sum)[,1] [,2] [,3] [,4] [1,] 2 8 14 20 [2,] 4 10 16 22 [3,] 6 12 18 24 Cheers Petr> anyone could give an idea of how to write a function for this. > > Thanks, > Alejandra > > [[alternative HTML version deleted]] > > ______________________________________________ > 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.________________________________ Tento e-mail a jak?koliv k n?mu p?ipojen? dokumenty jsou d?v?rn? a jsou ur?eny pouze jeho adres?t?m. Jestli?e jste obdr?el(a) tento e-mail omylem, informujte laskav? neprodlen? jeho odes?latele. Obsah tohoto emailu i s p??lohami a jeho kopie vyma?te ze sv?ho syst?mu. Nejste-li zam??len?m adres?tem tohoto emailu, nejste opr?vn?ni tento email jakkoliv u??vat, roz?i?ovat, kop?rovat ?i zve?ej?ovat. Odes?latel e-mailu neodpov?d? za eventu?ln? ?kodu zp?sobenou modifikacemi ?i zpo?d?n?m p?enosu e-mailu. 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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. 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Your message seems unclear, and as evidence the respondents are giving various
answers. You should provide a small sample of input and output data as it would
look in R to avoid this kind of thrashing about. See [1][2][3] for guidance.
Note that you also really need to figure out how to make sure your email program
sends plain text, because HTML formatting WILL be stripped by the mailing list
(read the Posting Guide) and that process often garbles it.
My own possibly-confused reading of your question ("each cvs file has 47
rows and colunms, so the final data frame should have the same") is that
you do not yet understand the difference between matrices and data frames ([4]),
and you want to perform matrix (element-wise) addition. This would require that
you convert the data frames read in by read.csv into matrices before adding
them:
All_data <- lapply(filenames
,function(i){
###read cvs files and add the row and column names to each data frame
###
as.matrix( read.csv(i, header=FALSE, sep = "", col.names = col_names,
row.names = row_names)
})
result <- Reduce( `+`, All_data )
This will fail if any of the values in your csv files are non-numeric, but
dealing with that would require us to know specifics about your files or intent
that you have omitted. (The dput function is indispensable for clarifying such
issues [1][2].)
---
[1]
http://stackoverflow.com/questions/5963269/how-to-make-a-great-r-reproducible-example
[2] http://adv-r.had.co.nz/Reproducibility.html
[3] https://cran.r-project.org/web/packages/reprex/index.html (read the
vignette)
[4] see "Introduction to R" (part of the R documentation)
--
Sent from my phone. Please excuse my brevity.
On January 15, 2018 1:29:05 AM PST, Alejandra Lopez-Galan <alejandra7galan at
gmail.com> wrote:>Hi, I am pretty new to R and I would apreciatte very much your help to
>solve my problem. I have 40 csv files that have the same structure, and
>I
>want to merge them into a single data frame.
>
>I already have load and combined all the cvs files into a large list,
>and I
>created two
>
>filenames <- list.files('data',full.names=TRUE)
>
>All_data <- lapply(filenames,function(i){
>###read cvs files and add the row and column names to each data
>frame###
> read.csv(i, header=FALSE, sep = "", col.names = col_names,
row.names >row_names)
> })
>
>However I would like to sum the rows of cvs files to get a single data
>frame (each cvs file has 47 rows and colunms, so the final data frame
>should have the same). I could only do it one by one data data frame,
>but I
>was wondering if anyone could give an idea of how to write a function
>for
>this.
>
>Thanks,
>Alejandra
>
> [[alternative HTML version deleted]]
>
>______________________________________________
>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.
Hi all, Thanks for your help and sorry for the confusion. Also Thanks Jeff, your solution worked well, I was trying to perform matrix (element-wise) addition as you mentioned, but I didn't know how to formulate my question. Thanks for the references, they also help me to understand more. Cheers, Alejandra On Tue, Jan 16, 2018 at 2:35 AM, Jeff Newmiller <jdnewmil at dcn.davis.ca.us> wrote:> Your message seems unclear, and as evidence the respondents are giving various answers. You should provide a small sample of input and output data as it would look in R to avoid this kind of thrashing about. See [1][2][3] for guidance. Note that you also really need to figure out how to make sure your email program sends plain text, because HTML formatting WILL be stripped by the mailing list (read the Posting Guide) and that process often garbles it. > > My own possibly-confused reading of your question ("each cvs file has 47 rows and colunms, so the final data frame should have the same") is that you do not yet understand the difference between matrices and data frames ([4]), and you want to perform matrix (element-wise) addition. This would require that you convert the data frames read in by read.csv into matrices before adding them: > > All_data <- lapply(filenames > ,function(i){ > ###read cvs files and add the row and column names to each data frame > ### > as.matrix( read.csv(i, header=FALSE, sep = "", col.names = col_names, row.names = row_names) > }) > > result <- Reduce( `+`, All_data ) > > This will fail if any of the values in your csv files are non-numeric, but dealing with that would require us to know specifics about your files or intent that you have omitted. (The dput function is indispensable for clarifying such issues [1][2].) > --- > > [1] http://stackoverflow.com/questions/5963269/how-to-make-a-great-r-reproducible-example > > [2] http://adv-r.had.co.nz/Reproducibility.html > > [3] https://cran.r-project.org/web/packages/reprex/index.html (read the vignette) > > [4] see "Introduction to R" (part of the R documentation) > > -- > Sent from my phone. Please excuse my brevity. > > On January 15, 2018 1:29:05 AM PST, Alejandra Lopez-Galan <alejandra7galan at gmail.com> wrote: >>Hi, I am pretty new to R and I would apreciatte very much your help to >>solve my problem. I have 40 csv files that have the same structure, and >>I >>want to merge them into a single data frame. >> >>I already have load and combined all the cvs files into a large list, >>and I >>created two >> >>filenames <- list.files('data',full.names=TRUE) >> >>All_data <- lapply(filenames,function(i){ >>###read cvs files and add the row and column names to each data >>frame### >> read.csv(i, header=FALSE, sep = "", col.names = col_names, row.names >>row_names) >> }) >> >>However I would like to sum the rows of cvs files to get a single data >>frame (each cvs file has 47 rows and colunms, so the final data frame >>should have the same). I could only do it one by one data data frame, >>but I >>was wondering if anyone could give an idea of how to write a function >>for >>this. >> >>Thanks, >>Alejandra >> >> [[alternative HTML version deleted]] >> >>______________________________________________ >>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.