Few more things about merging in R


R Tutorial 5.1


In the last article "A to Z about Merging in R", I had tried to cover almost everything about merging in R. Few things, I believe I have missed, are being covered in this article.

So have fun !

Complication A:


In the previous article we had addressed only to the situations where there were only 1 matching keys; What if the matching keys are more than 1.  Let's see how to merge in this case.

#Let's prepare two dataset:

Data_1 = data.frame(year = c( rep(2010,3),rep(2011,3))  , month = seq(1:6), rainfall = c(111,123,134,145,170,184) )
Data_2 = data.frame(year = c( rep(2010,3),rep(2011,3))  , month = seq(1:6), Temp_celcius = c(23,20,21,18,14,19) )

Now the matching key here is year + month

Data_merged= merge(Data_1, Data_2, by = c("year","month" ))

Please run and see the results.

Complication B:


The name of matching key(s) is/are not same across datasets.

# As a matter of best practice, first we clear the workspace
rm(list = ls())

#Let's prepare two dataset, this time in second dataset, one of the matching keys has been given a different name

Data_1 = data.frame(year = c( rep(2010,3),rep(2011,3))  , month = seq(1:6), rainfall = c(111,123,134,145,170,184) )
Data_2 = data.frame(year = c( rep(2010,3),rep(2011,3))  , mon_id = seq(1:6), Temp_celcius = c(23,20,21,18,14,19) )


Data_merged= merge(x= Data_1, y= Data_2, by.x = c("year","month" ), by.y = c("year","mon_id" ))


Please run and see the results.


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