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How to find the trimmed mean for a column of an R data frame?
Trimmed mean is the mean that find the mean of values by excluding a small percentage of smallest and largest values. If we have a 5% trimmed mean that means 2.5% of smallest values and 2.5% of largest values are trimmed from the data and then the mean of the remaining data is calculated.
In R, we can simply use trim argument inside mean function to find the trimmed mean. Check out the below Examples to understand how it can be done.
Example 1
Following snippet creates a sample data frame −
x<-rpois(20,10) df1<-data.frame(x) df1
The following dataframe is created
x 1 9 2 9 3 13 4 10 5 10 6 7 7 14 8 9 9 4 10 13 11 17 12 9 13 12 14 13 15 7 16 7 17 7 18 7 19 11 20 8
To find 5% trimmed mean of column x in df1 on the above created data frame, add the following code to the above snippet −
x<-rpois(20,10) df1<-data.frame(x) mean(df1$x,trim=0.05)
Output
If you execute all the above given snippets as a single program, it generates the following Output −
[1] 9.722222
Example 2
Following snippet creates a sample data frame −
y<-rnorm(20) df2<-data.frame(y) df2
The following dataframe is created
y 1 -0.2275112 2 -0.3068841 3 1.4224841 4 -0.2046823 5 -0.6992631 6 1.3496018 7 -1.3079773 8 1.7224761 9 0.4276027 10 0.7502251 11 -0.5527819 12 0.5962074 13 -1.4589839 14 1.8237570 15 -0.4459367 16 0.6482315 17 1.3998148 18 -0.7622238 19 1.1308999 20 -0.2575229
To find 5% trimmed mean of column y in df2 on the above created data frame, add the following code to the above snippet −
y<-rnorm(20) df2<-data.frame(y) mean(df2$y,trim=0.05)
Output
If you execute all the above given snippets as a single program, it generates the following Output −
[1] 0.2601533
Example 3
Following snippet creates a sample data frame −
z<-rexp(20) df3<-data.frame(z) df3
The following dataframe is created
z 1 3.41614687 2 0.29851851 3 0.72436257 4 0.65434257 5 1.11213684 6 0.08191155 7 2.03424614 8 0.53371331 9 0.08343326 10 0.37775986 11 0.30124390 12 0.42210175 13 0.86609511 14 1.62482612 15 1.30000247 16 4.68351724 17 0.40375151 18 0.36646246 19 0.92898766 20 0.47307554
To find 5% trimmed mean of column z in df3 on the above created data frame, add the following code to the above snippet −
z<-rexp(20) df3<-data.frame(z) mean(df3$z,trim=0.05)
Output
If you execute all the above given snippets as a single program, it generates the following Output −
[1] 0.8845115
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