# Getting Familiar With R

Want to learn more? I recommend working through: R for Data Science, R Cookbook, and R Graphics Cookbook.

# Arithmetic operators 1 + 1 # 1 plus 1 4 - 3 # 4 minus 3 14 / 10 # 14 divided by 10 10*5 # 10 multiplied by 5 3^2 # 3 squared 5%%2 # 5 mod 2 4%/%2 # 4 divided by 2 (integer division)

[1] 2 [1] 1 [1] 1.4 [1] 50 [1] 9 [1] 1 [1] 2

# Logical operators 2 < 4 # 2 is less than 4 2 <= 4 # 2 is less than or equal to 4 2 > 4 # 2 is greater than 4 3 >= 5 # 3 is greater than or equal to 5 5 == 5 # 5 is equal to 5 5 != 4 # 5 is not equal to 4 !2 # Not 2 2 | 4 # 2 or 4 4 & 5 # 3 and 5 isTRUE(4 + 4 == 8) # is "4 plus 4 equals 5" true?

[1] TRUE [1] TRUE [1] FALSE [1] FALSE [1] TRUE [1] TRUE [1] FALSE [1] TRUE [1] TRUE [1] TRUE

## How R Handles Data

In R, a collection of one or more values is called a vector. Think of vectors as a collection of numbers.

# We can create a vector by creating an object my.age <- 29 # create an vector object called my.age that contains the value "29" my.age # view the contents of our.ages our.ages <- c(29, 29, 43, 4) # create a vector object called our.ages containing the values 29, 29, 43, and 4 our.ages # view the contents of our.ages

[1] 29 [1] 29 29 43 4

Notice two things about these objects. First I am giving them very descriptive names. Second, I am seperating words with periods since spaces are not allowed in object names.

# We can even create objects from objects number.of.us <- length(our.ages) # create a vector object called number.of.us whose value is the length of the our.ages vector number.of.us # view the contents of number.of.us

[1] 4

# We can even tell R to create values for us one.to.ten <- 1:10 # create an object called one.to.ten that contains the all integiers between one and ten

# We can also do a lot of different functions with vector objects max(our.ages) # find the maximum value in our.ages min(our.ages) # find the minimum value in our.ages sum(our.ages) # find the sum of all values in our.ages mean(our.ages) # find the mean of all values in our.ages median(our.ages) # find the median of all values in our.ages range(our.ages) # find the range of all values in our.ages sort(our.ages) # sort values in our.ages in ascending order rank(our.ages) # rank the values in our.ages order(our.ages) # display the ascending order of the values in our.ages quantile(our.ages) # display the minimum, lower quartile, median, upper quartile, and maxmimum of our.ages

[1] 43 [1] 4 [1] 105 [1] 26.25 [1] 29 [1] 4 43 [1] 4 29 29 43 [1] 2.5 2.5 4.0 1.0 [1] 4 1 2 3 0% 25% 50% 75% 100% 4.00 22.75 29.00 32.50 43.00