R Extract Rows of Data Frame by Factor Levels (2 Examples)

data(iris)                                # Loading iris 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) # Loading iris 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

iris_subset1 <- iris[iris$Species ==      # Extract one factor level
                       "versicolor", ]
head(iris_subset1)                        # Show new data
#    Sepal.Length Sepal.Width Petal.Length Petal.Width    Species
# 51          7.0         3.2          4.7         1.4 versicolor
# 52          6.4         3.2          4.5         1.5 versicolor
# 53          6.9         3.1          4.9         1.5 versicolor
# 54          5.5         2.3          4.0         1.3 versicolor
# 55          6.5         2.8          4.6         1.5 versicolor
# 56          5.7         2.8          4.5         1.3 versicolor

iris_subset1 <- iris[iris$Species == # Extract one factor level "versicolor", ] head(iris_subset1) # Show new data # Sepal.Length Sepal.Width Petal.Length Petal.Width Species # 51 7.0 3.2 4.7 1.4 versicolor # 52 6.4 3.2 4.5 1.5 versicolor # 53 6.9 3.1 4.9 1.5 versicolor # 54 5.5 2.3 4.0 1.3 versicolor # 55 6.5 2.8 4.6 1.5 versicolor # 56 5.7 2.8 4.5 1.3 versicolor

iris_subset2 <- iris[iris$Species %in%    # Extract multiple factor levels
                       c("setosa", "versicolor"), ]
head(iris_subset2)                        # Show new data
#   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

iris_subset2 <- iris[iris$Species %in% # Extract multiple factor levels c("setosa", "versicolor"), ] head(iris_subset2) # Show new data # 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