CODEWITHSUNDEEP
rcsvmerge
jewish.cowboy
jewish.cowboy

Reputation: 121

How to join data from 2 different csv-files in R?

I have the following problem: in a csv-file I have a column for species, one for transect, one for the year and one for the AUC. In another csv-file I have a column for transect, one for the year, one for precipitation and one for temperature. Now I would like to join the files in R in a way, that I can have the columns for species and AUC from the second csv and the columns for the rest from the first csv. In the end I'd like to get a file with transect_id, year, day, month, species, regional_gam(=AUC), precipitation and LST(=temperature). So basically the precipitation-/ LST-values from TR001 for every day in 2008 need to be assigned to every species which has an AUC-value for 2008 and TR001. Thanks!

Upvotes: 4

Views: 31454

Answers (3)

Khalil Youssefi
Khalil Youssefi

Reputation: 414

In general, to merge .csv files, you can simply use this code snip:

path <- rstudioapi::getActiveDocumentContext()$path
Encoding(path) <- "UTF-8"
setwd(dirname(path))

datap1 = read.csv("file1.csv", header=TRUE)
datap2 = read.csv("file2.csv", header=TRUE)
data <- rbind(datap1, datap2)
write.csv(data,"merged.csv")

Note: First 3 lines of code set the working directory to where the R file is located and are not related to the question.

Upvotes: 0

Syed Samiul Haque
Syed Samiul Haque

Reputation: 1

Please use

library(dplyr)

df1<- read.csv("F:\\Test_Anything\\Merge\\1.csv" , head(T))
df2<-read.csv("F:\\Test_Anything\\Merge\\2.csv" , head(T))
r <- merge(df1,df2,by=c('NAME','NAME'),all.x=T)
write.csv(r,"F:\\Test_Anything\\Merge\\DF.csv" , all(T) )

Upvotes: 0

theforestecologist
theforestecologist

Reputation: 4957

Use read.csv and then merge.

Load the two csv files into R. (Don't forget to make sure their common variables share the same name!).

df1<-read.csv(dat1,head=T)
df2<-read.csv(dat2,head=T)

Merge the dataframes together by their shared variables and add argument all.x=T (the default) to ensure all rows are kept from your database containing species. 

merge(df1,df2,by=c('transect_id','year'),all.x=T)

To see this in action using test data:

test<-data.frame(sp=c(rep(letters[1:10],2)),t=c(rep(1:3,2,20)),y=c(rep(2000:2008,len=20)),AUC=1:20)
test2<-data.frame(t=c(rep(1:3,2,9)),y=c(rep(2000:2008,len=9)),ppt=c(1:9),temp=c(11:19))

merge(test,test2,by=c('t','y'),all.x=T)

Upvotes: 4

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