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How to find the total by year column in an R data frame?
To find the total by year column in an R data frame, we can use aggregate function with sum function.
For Example, if we have a data frame called df that contains a year colmn say Year and a numerical column say Demand then we can find the total Demand by Year with the help of command given below −
aggregate(df["Demand"],by=df["Year"],sum)
Example 1
Following snippet creates a sample data frame −
Year<-sample(2001:2005,20,replace=TRUE) Sales<-sample(500:1000,20) df1<-data.frame(Year,Sales) df1
The following dataframe is created
Year Sales 1 2001 537 2 2005 742 3 2003 551 4 2003 590 5 2001 792 6 2003 985 7 2003 765 8 2003 993 9 2003 764 10 2003 855 11 2001 959 12 2004 607 13 2002 555 14 2002 566 15 2005 596 16 2003 714 17 2005 846 18 2004 910 19 2005 849 20 2002 740
To find total Sales by Year on the above created data frame, add the following code to the above snippet −
Year<-sample(2001:2005,20,replace=TRUE) Sales<-sample(500:1000,20) df1<-data.frame(Year,Sales) aggregate(df1["Sales"],by=df1["Year"],sum)
Output
If you execute all the above given snippets as a single program, it generates the following Output −
Year Sales 1 2001 2288 2 2002 1861 3 2003 6217 4 2004 1517 5 2005 3033
Example 2
Following snippet creates a sample data frame −
Years<-sample(2011:2016,20,replace=TRUE) GDP_Variation<-sample(1:10,20,replace=TRUE) df2<-data.frame(Years,GDP_Variation) df2
The following dataframe is created
Years GDP_Variation 1 2011 10 2 2011 7 3 2014 3 4 2016 8 5 2012 10 6 2016 9 7 2011 9 8 2013 7 9 2016 3 10 2016 6 11 2016 6 12 2012 3 13 2013 6 14 2015 5 15 2013 1 16 2011 8 17 2013 4 18 2015 5 19 2016 7 20 2013 8
To find total GDP_Variation by Years on the above created data frame, add the following code to the above snippet −
Years<-sample(2011:2016,20,replace=TRUE) GDP_Variation<-sample(1:10,20,replace=TRUE) df2<-data.frame(Years,GDP_Variation) aggregate(df2["GDP_Variation"],by=df2["Years"],sum)
Output
If you execute all the above given snippets as a single program, it generates the following Output −
Years GDP_Variation 1 2011 34 2 2012 13 3 2013 26 4 2014 3 5 2015 10 6 2016 39
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