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R Version 2.11.1 32-bit on Windows 7
I got two data sets: data_A and data_B:
USER_A USER_B ACTION 1 11 0.3 1 13 0.25 1 16 0.63 1 17 0.26 2 11 0.14 2 14 0.28 USER_A USER_B ACTION 1 13 0.17 1 14 0.27 2 11 0.25 Now I want to add the ACTION of data_B to the data_A if their USER_A and USER_B are equal. As the example above, the result would be:
USER_A USER_B ACTION 1 11 0.3 1 13 0.25+0.17 1 16 0.63 1 17 0.26 2 11 0.14+0.25 2 14 0.28 So how could I achieve it?
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The merge() function in base R can be used to merge input dataframes by common columns or row names. The merge() function retains all the row names of the dataframes, behaving similarly to the inner join. The dataframes are combined in order of the appearance in the input function call.
To join two data frames (datasets) vertically, use the rbind function. The two data frames must have the same variables, but they do not have to be in the same order. If data frameA has variables that data frameB does not, then either: Delete the extra variables in data frameA or.
In R we use merge() function to merge two dataframes in R. This function is present inside join() function of dplyr package. The most important condition for joining two dataframes is that the column type should be the same on which the merging happens. merge() function works similarly like join in DBMS.
How do I concatenate two columns in R? To concatenate two columns you can use the <code>paste()</code> function. For example, if you want to combine the two columns A and B in the dataframe df you can use the following code: <code>df['AB'] <- paste(df$A, df$B)</code>.
You can use ddply in package plyr and combine it with merge:
library(plyr) ddply(merge(data_A, data_B, all.x=TRUE), .(USER_A, USER_B), summarise, ACTION=sum(ACTION)) Notice that merge is called with the parameter all.x=TRUE - this returns all of the values in the first data.frame passed to merge, i.e. data_A:
USER_A USER_B ACTION 1 1 11 0.30 2 1 13 0.25 3 1 16 0.63 4 1 17 0.26 5 2 11 0.14 6 2 14 0.28 If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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