[R: package swirl]Selection: 3 Sequences of Numbers
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Selection: 3 Sequences of Numbers
| | 0%
| In this lesson, you’ll learn how to create
| sequences of numbers in R.
…
|== | 4%
| The simplest way to create a sequence of numbers in R is by using the :
| operator. Type 1:20 to see how it works.
1:20
[1] 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
[16] 16 17 18 19 20
| You are really on a roll!
|=== | 9%
| That gave us every integer between (and
| including) 1 and 20. We could also use it to
| create a sequence of real numbers. For example,
| try pi:10.
pi:10
[1] 3.141593 4.141593 5.141593 6.141593 7.141593
[6] 8.141593 9.141593
| You are really on a roll!
|===== | 13%
| The result is a vector of real numbers starting
| with pi (3.142…) and increasing in increments
| of 1. The upper limit of 10 is never reached,
| since the next number in our sequence would be
| greater than 10.
…
|======= | 17%
| What happens if we do 15:1? Give it a try to
| find out.
15:1
[1] 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1
| That’s a job well done!
|========= | 22%
| It counted backwards in increments of 1! It’s
| unlikely we’d want this behavior, but
| nonetheless it’s good to know how it could
| happen.
…
|========== | 26%
| Remember that if you have questions about a
| particular R function, you can access its
| documentation with a question mark followed by
| the function name: ?function_name_here.
| However, in the case of an operator like the
| colon used above, you must enclose the symbol
| in backticks like this: ?:. (NOTE: The
| backtick (`) key is generally located in the
| top left corner of a keyboard, above the Tab
| key. If you don’t have a backtick key, you can
| use regular quotes.)
…?:
|============ | 30%
| Pull up the documentation for : now.
?
:
| Your dedication is inspiring!
|============== | 35%
| Often, we’ll desire more control over a
| sequence we’re creating than what the :
| operator gives us. The seq() function serves
| this purpose.
…
|================ | 39%
| The most basic use of seq() does exactly the
| same thing as the : operator. Try seq(1, 20)
| to see this.
seq(1,20)
[1] 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
[16] 16 17 18 19 20
| Keep up the great work!
|================= | 43%
| This gives us the same output as 1:20. However,
| let’s say that instead we want a vector of
| numbers ranging from 0 to 10, incremented by
| 0.5. seq(0, 10, by=0.5) does just that. Try it
| out.
seq(0,10,by=0.5)
[1] 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
[10] 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5
[19] 9.0 9.5 10.0
| That’s a job well done!
|=================== | 48%
| Or maybe we don’t care what the increment is
| and we just want a sequence of 30 numbers
| between 5 and 10. seq(5, 10, length=30) does
| the trick. Give it a shot now and store the
| result in a new variable called my_seq.
my_seq=seq(5,10,length=30)
| Nice try, but that’s not exactly what I was
| hoping for. Try again. Or, type info() for more
| options.
| You’re using the same function here, but
| changing its arguments for different results.
| Be sure to store the result in a new variable
| called my_seq, like this: my_seq <- seq(5, 10,
| length=30).
my_seq <- seq(5,10,length=30)
| You are doing so well!
|===================== | 52%
| To confirm that my_seq has length 30, we can
| use the length() function. Try it now.
length(my_seq)
[1] 30
| You got it right!
|======================= | 57%
| Let’s pretend we don’t know the length of
| my_seq, but we want to generate a sequence of
| integers from 1 to N, where N represents the
| length of the my_seq vector. In other words, we
| want a new vector (1, 2, 3, …) that is the
| same length as my_seq.
…
|======================== | 61%
| There are several ways we could do this. One
| possibility is to combine the : operator and
| the length() function like this:
| 1:length(my_seq). Give that a try.
1:length(my_seq)
[1] 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
[16] 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
| You nailed it! Good job!
|========================== | 65%
| Another option is to use seq(along.with =
| my_seq). Give that a try.
seq(along.with=my_seq)
[1] 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
[16] 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
| All that hard work is paying off!
|============================ | 70%
| However, as is the case with many common tasks,
| R has a separate built-in function for this
| purpose called seq_along(). Type
| seq_along(my_seq) to see it in action.
seq_along(my_seq)
[1] 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
[16] 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
| You are really on a roll!
|============================== | 74%
| There are often several approaches to solving
| the same problem, particularly in R. Simple
| approaches that involve less typing are
| generally best. It’s also important for your
| code to be readable, so that you and others can
| figure out what’s going on without too much
| hassle.
…
|=============================== | 78%
| If R has a built-in function for a particular
| task, it’s likely that function is highly
| optimized for that purpose and is your best
| option. As you become a more advanced R
| programmer, you’ll design your own functions to
| perform tasks when there are no better options.
| We’ll explore writing your own functions in
| future lessons.
…
|================================= | 83%
| One more function related to creating sequences
| of numbers is rep(), which stands for
| ‘replicate’. Let’s look at a few uses.
…
|=================================== | 87%
| If we’re interested in creating a vector that
| contains 40 zeros, we can use rep(0, times =
| 40). Try it out.
rep(0,times=40)
[1] 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
[24] 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
| All that practice is paying off!
|===================================== | 91%
| If instead we want our vector to contain 10
| repetitions of the vector (0, 1, 2), we can do
| rep(c(0, 1, 2), times = 10). Go ahead.
rep(c(0,1,2),times=10)
[1] 0 1 2 0 1 2 0 1 2 0 1 2 0 1 2 0 1 2 0 1 2 0 1
[24] 2 0 1 2 0 1 2
| Great job!
|====================================== | 96%
| Finally, let’s say that rather than repeating
| the vector (0, 1, 2) over and over again, we
| want our vector to contain 10 zeros, then 10
| ones, then 10 twos. We can do this with the
| each argument. Try rep(c(0, 1, 2), each =
| 10).
rep(c(0,1,2),each=10)
[1] 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 2 2 2
[24] 2 2 2 2 2 2 2
| Great job!
|========================================| 100%
| Would you like to receive credit for completing
| this course on Coursera.org?
1: No
2: Yes
Selection: 1
| Excellent work!
| You’ve reached the end of this lesson!
| Returning to the main menu…
| Please choose a course, or type 0 to exit
| swirl.
1: R Programming
2: Take me to the swirl course repository!
Selection: 1
| Please choose a lesson, or type 0 to return to
| course menu.
1: Basic Building Blocks
2: Workspace and Files
3: Sequences of Numbers
4: Vectors
5: Missing Values
6: Subsetting Vectors
7: Matrices and Data Frames
8: Logic
9: Functions
10: lapply and sapply
11: vapply and tapply
12: Looking at Data
13: Simulation
14: Dates and Times
15: Base Graphics
Selection:
Enter an item from the menu, or 0 to exit
Selection: bye()
Enter an item from the menu, or 0 to exit
Selection: exit
Enter an item from the menu, or 0 to exit
Selection: 0
| Please choose a course, or type 0 to exit
| swirl.
1: R Programming
2: Take me to the swirl course repository!
Selection: bye()
Enter an item from the menu, or 0 to exit
Selection: 0
| Leaving swirl now. Type swirl() to resume.
Selection: 3
| | 0%
| In this lesson, you’ll learn how to create
| sequences of numbers in R.
…
|== | 4%
| The simplest way to create a sequence of numbers in R is by using the :
| operator. Type 1:20 to see how it works.
1:20
[1] 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
[16] 16 17 18 19 20
| You are really on a roll!
|=== | 9%
| That gave us every integer between (and
| including) 1 and 20. We could also use it to
| create a sequence of real numbers. For example,
| try pi:10.
pi:10
[1] 3.141593 4.141593 5.141593 6.141593 7.141593
[6] 8.141593 9.141593
| You are really on a roll!
|===== | 13%
| The result is a vector of real numbers starting
| with pi (3.142…) and increasing in increments
| of 1. The upper limit of 10 is never reached,
| since the next number in our sequence would be
| greater than 10.
…
|======= | 17%
| What happens if we do 15:1? Give it a try to
| find out.
15:1
[1] 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1
| That’s a job well done!
|========= | 22%
| It counted backwards in increments of 1! It’s
| unlikely we’d want this behavior, but
| nonetheless it’s good to know how it could
| happen.
…
|========== | 26%
| Remember that if you have questions about a
| particular R function, you can access its
| documentation with a question mark followed by
| the function name: ?function_name_here.
| However, in the case of an operator like the
| colon used above, you must enclose the symbol
| in backticks like this: ?:. (NOTE: The
| backtick (`) key is generally located in the
| top left corner of a keyboard, above the Tab
| key. If you don’t have a backtick key, you can
| use regular quotes.)
…?:
|============ | 30%
| Pull up the documentation for : now.
?
:
| Your dedication is inspiring!
|============== | 35%
| Often, we’ll desire more control over a
| sequence we’re creating than what the :
| operator gives us. The seq() function serves
| this purpose.
…
|================ | 39%
| The most basic use of seq() does exactly the
| same thing as the : operator. Try seq(1, 20)
| to see this.
seq(1,20)
[1] 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
[16] 16 17 18 19 20
| Keep up the great work!
|================= | 43%
| This gives us the same output as 1:20. However,
| let’s say that instead we want a vector of
| numbers ranging from 0 to 10, incremented by
| 0.5. seq(0, 10, by=0.5) does just that. Try it
| out.
seq(0,10,by=0.5)
[1] 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
[10] 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5
[19] 9.0 9.5 10.0
| That’s a job well done!
|=================== | 48%
| Or maybe we don’t care what the increment is
| and we just want a sequence of 30 numbers
| between 5 and 10. seq(5, 10, length=30) does
| the trick. Give it a shot now and store the
| result in a new variable called my_seq.
my_seq=seq(5,10,length=30)
| Nice try, but that’s not exactly what I was
| hoping for. Try again. Or, type info() for more
| options.
| You’re using the same function here, but
| changing its arguments for different results.
| Be sure to store the result in a new variable
| called my_seq, like this: my_seq <- seq(5, 10,
| length=30).
my_seq <- seq(5,10,length=30)
| You are doing so well!
|===================== | 52%
| To confirm that my_seq has length 30, we can
| use the length() function. Try it now.
length(my_seq)
[1] 30
| You got it right!
|======================= | 57%
| Let’s pretend we don’t know the length of
| my_seq, but we want to generate a sequence of
| integers from 1 to N, where N represents the
| length of the my_seq vector. In other words, we
| want a new vector (1, 2, 3, …) that is the
| same length as my_seq.
…
|======================== | 61%
| There are several ways we could do this. One
| possibility is to combine the : operator and
| the length() function like this:
| 1:length(my_seq). Give that a try.
1:length(my_seq)
[1] 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
[16] 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
| You nailed it! Good job!
|========================== | 65%
| Another option is to use seq(along.with =
| my_seq). Give that a try.
seq(along.with=my_seq)
[1] 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
[16] 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
| All that hard work is paying off!
|============================ | 70%
| However, as is the case with many common tasks,
| R has a separate built-in function for this
| purpose called seq_along(). Type
| seq_along(my_seq) to see it in action.
seq_along(my_seq)
[1] 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
[16] 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
| You are really on a roll!
|============================== | 74%
| There are often several approaches to solving
| the same problem, particularly in R. Simple
| approaches that involve less typing are
| generally best. It’s also important for your
| code to be readable, so that you and others can
| figure out what’s going on without too much
| hassle.
…
|=============================== | 78%
| If R has a built-in function for a particular
| task, it’s likely that function is highly
| optimized for that purpose and is your best
| option. As you become a more advanced R
| programmer, you’ll design your own functions to
| perform tasks when there are no better options.
| We’ll explore writing your own functions in
| future lessons.
…
|================================= | 83%
| One more function related to creating sequences
| of numbers is rep(), which stands for
| ‘replicate’. Let’s look at a few uses.
…
|=================================== | 87%
| If we’re interested in creating a vector that
| contains 40 zeros, we can use rep(0, times =
| 40). Try it out.
rep(0,times=40)
[1] 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
[24] 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
| All that practice is paying off!
|===================================== | 91%
| If instead we want our vector to contain 10
| repetitions of the vector (0, 1, 2), we can do
| rep(c(0, 1, 2), times = 10). Go ahead.
rep(c(0,1,2),times=10)
[1] 0 1 2 0 1 2 0 1 2 0 1 2 0 1 2 0 1 2 0 1 2 0 1
[24] 2 0 1 2 0 1 2
| Great job!
|====================================== | 96%
| Finally, let’s say that rather than repeating
| the vector (0, 1, 2) over and over again, we
| want our vector to contain 10 zeros, then 10
| ones, then 10 twos. We can do this with the
| each argument. Try rep(c(0, 1, 2), each =
| 10).
rep(c(0,1,2),each=10)
[1] 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 2 2 2
[24] 2 2 2 2 2 2 2
| Great job!
|========================================| 100%
| Would you like to receive credit for completing
| this course on Coursera.org?
1: No
2: Yes
Selection: 1
| Excellent work!
| You’ve reached the end of this lesson!
| Returning to the main menu…
| Please choose a course, or type 0 to exit
| swirl.
1: R Programming
2: Take me to the swirl course repository!
Selection: 1
| Please choose a lesson, or type 0 to return to
| course menu.
1: Basic Building Blocks
2: Workspace and Files
3: Sequences of Numbers
4: Vectors
5: Missing Values
6: Subsetting Vectors
7: Matrices and Data Frames
8: Logic
9: Functions
10: lapply and sapply
11: vapply and tapply
12: Looking at Data
13: Simulation
14: Dates and Times
15: Base Graphics
Selection:
Enter an item from the menu, or 0 to exit
Selection: bye()
Enter an item from the menu, or 0 to exit
Selection: exit
Enter an item from the menu, or 0 to exit
Selection: 0
| Please choose a course, or type 0 to exit
| swirl.
1: R Programming
2: Take me to the swirl course repository!
Selection: bye()
Enter an item from the menu, or 0 to exit
Selection: 0
| Leaving swirl now. Type swirl() to resume.