# Let's first create a numeric and a character vector.
# There is no need to do this again if you already did it in the previous exercise!
> odd_n <- c(1, 3, 5, 7, 9)

# Extract the second element of the numeric vector.
> odd_n[2]
[1]  3

# Extract the second and fourth elements of the numeric vector.
> odd_n[c(2, 4)]
[1]  3 7

# Extract all but the two first elements of the numeric vector.
> odd_n[c(-1, -2)]
[1] 5 7 9

# If you select a position that is not in the numeric vector
> odd_n[c(1,6)]
[1] 1 NA
# There is no sixth value in this vector so R returns a null value (i.e. NA)
# NA stands for 'Not available'.

# You can use logical statement to select values.
> odd_n[odd_n > 4]
[1] 5 7 9

# Extract all elements of the character vector corresponding exactly to "blue".
> char_vecteur[char_vecteur == "blue"]
[1]  "bleu"
# Note the use of the double equal sign ==.