import numpy as np
import matplotlib.pyplot as plt
x = np.arange(0, 5, 0.1);
y = np.sin(x)
plt.plot(x, y)
plt.show()
# no pec
# Calculate 3 + 4
3 + 4
# Calculate 6 + 12
# Calculate 3 + 4
3 + 4
# Calculate 6 + 12
6 + 12
test_output_contains("18", incorrect_msg = "Make sure to add `6 + 12`
on
a new line. Do not start the line with a `#`, otherwise your R code is not executed!")
success_msg("Awesome! See how the console shows the result of the R code you
submitted? Now that you're familiar with the interface, let's get down to R
business!")
Just add a line of R code that calculates the sum of 6 and 12, just like the example in the sample code!
# no pec
# An addition
5 + 5
# A subtraction
5 - 5
# A multiplication
3 * 5
# A division
(5 + 5) / 2
# Exponentiation
# Modulo
# An addition
5 + 5
# A subtraction
5 - 5
# A multiplication
3 * 5
# A division
(5 + 5) / 2
# Exponentiation
2 ^ 5
# Modulo
28 %% 6
msg = "Do not remove the other arithmetic examples!"
test_output_contains("2^5", incorrect_msg = "The exponentiation
example
is not correct. Write `2 ^ 5` on a new line.")
test_output_contains("28 %% 6", incorrect_msg = "There seems to be an
issue with the modulo example. Write `28 %% 6` on a new line.")
success_msg("Great! Head over to the next exercise.")
Another example of the modulo operator:
9 %% 2 equals
1.
# no pec
# Assign the value 42 to x
x <-
# Print out the value of the variable x
x
# Assign the value 42 to x
x <- 42
# Print out the value of the variable x
x
test_object("x", undefined_msg = "Make sure to define a variable `x`.",
incorrect_msg = "Make sure that you assign the correct value to `x`.")
success_msg("Good job! Have you noticed that R does not print the value of a
variable to the console when you did the assignment? `x <- 42` did not generate
any
output, because R assumes that you will be needing this variable in the future.
Otherwise you wouldn't have stored the value in a variable in the first place,
right? Proceed to the next exercise!")
Look at how the value 4 was assigned to
my_variable in the exercise's assignment. Do the exact same
thing
in the editor, but now assign 42 to the variable
x.
# no pec
# Assign the value 5 to the variable my_apples
# Print out the value of the variable my_apples
# Assign the value 5 to the variable my_apples
my_apples <- 5
# Print out the value of the variable my_apples
my_apples
test_object("my_apples",
undefined_msg = "Please make sure to define a variable `my_apples`.",
incorrect_msg = "Make sure that you assign the correct value to `my_apples`.")
test_output_contains("my_apples", incorrect_msg = "Have you
explicitly
told R to print out the `my_apples` variable to the console?")
success_msg("Great! Continue to the next exercise!")
Remember that if you want to assign a number or an object to a variable in R, you
can
make use of the assignment operator
<-. Alternatively, you can use
=, but
<- is widely preferred in the R community.
# no pec
# Assign a value to the variables my_apples and my_oranges
my_apples <- 5
# Add these two variables together
# Create the variable my_fruit
# Assign a value to the variables my_apples and my_oranges
my_apples <- 5
my_oranges <- 6
# Add these two variables together
my_apples + my_oranges
# Create the variable my_fruit
my_fruit <- my_apples + my_oranges
test_object("my_apples", incorrect_msg = "Keep the line that assigns
5 to
`my_apples`.")
test_object("my_oranges", incorrect_msg = "Keep the line that assigns
6
to `my_oranges`.")
test_output_contains("my_apples + my_oranges",
incorrect_msg = "Make sure to print out the result of adding `my_apples` and
`my_oranges`. The code example in the description already gives away the answer to
this
instruction!")
msg <- "Have you used `my_fruit <- my_apples + my_oranges` to create the
`my_fruit` variable?"
test_object("my_fruit", undefined_msg = msg, incorrect_msg = msg)
success_msg("Nice one! The great advantage of doing calculations with variables
is
reusability. If you just change `my_apples` to equal 12 instead of 5 and rerun the
script, `my_fruit` will automatically update as well. Continue to the next exercise.")
my_fruit is just the sum of
my_apples and
my_oranges. You can use the
+ operator to sum the two and
<- to assign that value to the variable
my_fruit.
# no pec
# Assign a value to the variable my_apples
my_apples <- 5
# Fix the assignment of my_oranges
my_oranges <- "six"
# Create the variable my_fruit and print it out
my_fruit <- my_apples + my_oranges
my_fruit
# Assign a value to the variable my_apples
my_apples <- 5
# Fix the assignment of my_oranges
my_oranges <- 6
# Create the variable my_fruit and print it out
my_fruit <- my_apples + my_oranges
my_fruit
test_error(incorrect_msg = "You can do this by setting the `my_oranges`
variable to
a numeric value, not a string!")
test_object("my_apples", incorrect_msg = "Make sure that `my_apples`
still contains `5`.")
test_object("my_oranges", incorrect_msg = "Make sure that
`my_oranges` is
equal to `6`.")
test_object("my_fruit", incorrect_msg = "The value of `my_fruit` is
not
correct. It should be 11, the sum of `my_apples` and `my_oranges`.")
test_output_contains("my_fruit", incorrect_msg = "Don't remove
the
line that prints out `my_fruit`.")
success_msg("Awesome, keep up the good work! Continue to the next exercise.")
You have to assign the numeric value
6 to the
my_oranges variable instead of the character value
"six". Note how the quotation marks are used to indicate
that
"six" is a character.
# no pec
# Change my_numeric to be 42
my_numeric <- 42.5
# Change my_character to be "universe"
my_character <- "some text"
# Change my_logical to be FALSE
my_logical <- TRUE
# Change my_numeric to be 42
my_numeric <- 42
# Change my_character to be "universe"
my_character <- "universe"
# Change my_logical to be FALSE
my_logical <- FALSE
test_object("my_numeric", incorrect_msg = "Have you correctly changed
the
declaration of `my_numeric` so it contains the value 42?")
test_object("my_character", incorrect_msg = "Have you correctly
changed
`my_character` to `\"universe\"`? Don't forget the quotes!")
test_object("my_logical", incorrect_msg = "Have you correctly changed
`my_logical` to `FALSE`? All letters of `FALSE` should be capitalized!")
success_msg("Great work! Continue to the next exercise.")
Replace the values in the editor with the values that are provided in the
exercise.
For example:
my_numeric <- 42 assigns the value 42 to the variable
my_numeric.
# no pec
# Declare variables of different types
my_numeric <- 42
my_character <- "universe"
my_logical <- FALSE
# Check class of my_numeric
class(my_numeric)
# Check class of my_character
# Check class of my_logical
# Declare variables of different types:
my_numeric <- 42
my_character <- "universe"
my_logical <- FALSE
# Check class of my_numeric
class(my_numeric)
# Check class of my_character
class(my_character)
# Check class of my_logical
class(my_logical)
msg <- "Do not change the declaration of the variables!"
lapply(c("my_numeric", "my_character", "my_logical"),
test_object, undefined_msg = msg, incorrect_msg = msg)
patt <- "Have you included `class(%1$s)` to print out the data type of
`%1$s`?"
test_output_contains("class(my_numeric)",
incorrect_msg = "Do not remove the code that prints out the type of
`my_numeric`.")
test_output_contains("class(my_character)",
incorrect_msg = sprintf(patt, "my_character"))
test_output_contains("class(my_logical)",
incorrect_msg = sprintf(patt, "my_logical"))
success_msg("Congratulations! This was the last exercise for this chapter. Head
over to the next chapter to get immersed in the world of vectors!")
The code that prints the data type of
my_numeric is already included; do a similar things for
my_character and
my_logical.