How to Extract the First Row by Data Frame Group in R (Example Code)
This tutorial illustrates how to return the top line of each data table group in the R programming language.
Creating Example Data
data(iris) # Load & inspect first rows of data head(iris) # Sepal.Length Sepal.Width Petal.Length Petal.Width Species # 1 5.1 3.5 1.4 0.2 setosa # 2 4.9 3.0 1.4 0.2 setosa # 3 4.7 3.2 1.3 0.2 setosa # 4 4.6 3.1 1.5 0.2 setosa # 5 5.0 3.6 1.4 0.2 setosa # 6 5.4 3.9 1.7 0.4 setosa |
data(iris) # Load & inspect first rows of data head(iris) # Sepal.Length Sepal.Width Petal.Length Petal.Width Species # 1 5.1 3.5 1.4 0.2 setosa # 2 4.9 3.0 1.4 0.2 setosa # 3 4.7 3.2 1.3 0.2 setosa # 4 4.6 3.1 1.5 0.2 setosa # 5 5.0 3.6 1.4 0.2 setosa # 6 5.4 3.9 1.7 0.4 setosa
Example: Return First Row within Each Group of Iris Data Frame
iris[!duplicated(iris$Species), ] # Using duplicated function in R # Sepal.Length Sepal.Width Petal.Length Petal.Width Species # 1 5.1 3.5 1.4 0.2 setosa # 51 7.0 3.2 4.7 1.4 versicolor # 101 6.3 3.3 6.0 2.5 virginica |
iris[!duplicated(iris$Species), ] # Using duplicated function in R # Sepal.Length Sepal.Width Petal.Length Petal.Width Species # 1 5.1 3.5 1.4 0.2 setosa # 51 7.0 3.2 4.7 1.4 versicolor # 101 6.3 3.3 6.0 2.5 virginica