``````#####################################################################.
# In general, DO NOT use parentheses when they are clearly not necessary. ####
# It shows poor knowledge of the R language.
#####################################################################.

# Don't do this! - you never need parentheses around a single value
seq((1), (3))  ``````
`` 1 2 3``
``````# Don't do this! - unnecessary parentheses
(seq(1,3))   ``````
`` 1 2 3``
``````# Don't do this! - you never need parentheses around a single argument
x=2
seq(1,(3+x))  # do not put parentheses around a single argument``````
`` 1 2 3 4 5``
``````# This is the way to do it.
seq(1 , 3+x)  # better!``````
`` 1 2 3 4 5``
``````#####################################################################.
# It is acceptable to use extra parentheses when they are used to
# clarify the order of operations. Not everyone knows the order of
# operations by heart and this can make your code more readable.
#####################################################################.

# For example:

10-(2:10)``````
`` 8 7 6 5 4 3 2 1 0``
``````# is very different from

(10-2):10``````
``  8  9 10``
``````# The following (without the parentheses)
10-2:10``````
`` 8 7 6 5 4 3 2 1 0``
``````# is the same as 10-(2:10) as the order of operations lists the
# colon operator (:) before the subtraction operator (-)
# ( see ?Syntax )
#
# Therefore, I'd accept 10-(2:10) even thought strictly speaking the
# parentheses are not necessary as the parentheses help to clarify the
# order of operations.

############################################################################.
# QUESTION: The vector, x, contains at lest 3 values.
#           Write a command to show the last 3 values in the vector.
#           Your code must work no matter how many values are in the vector.
#
# Example 1:
#   > x = c("anne","bob","carla","dave","ed","fran","george","hugh","ike","jill")
#    "hugh" "ike" "jill"
#
# Example 2:
#   > x = seq(10,50,by=10)
#    30 40 50
############################################################################.

#------------.
#------------.

# Example 1:
x = c("anne","bob","carla","dave","ed","fran","george","hugh","ike","jill")
`` "hugh" "ike"  "jill"``
``````# Example 2:
x = seq(10,50,by=10)
`` 30 40 50``
``````#####################################################################.
# Don't use c(...) when it is not necessary  ####
#####################################################################.

# c() is only required to combine multiple vectors into a single vector.
# Do not use c for a single vector.

students = c("joe", "sue")   # c is required
c(students)     # c is not required - since there is only one vector - dont use c here``````
`` "joe" "sue"``
``students``
`` "joe" "sue"``
``c(seq(1,10,by=2))  # c is not required because seq is already a vector! - don't use c here``
`` 1 3 5 7 9``
``seq(1,10,by=2)``
`` 1 3 5 7 9``
``c ( rep(10,3), rep(20, 2))  # c IS required because you're combining two different vectors``
`` 10 10 10 20 20``