Workspace and Files

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| did then. If you are new, call yourself something unique.

What shall I call you? Krishnakanth Allika

| Please choose a course, or type 0 to exit swirl.

1: R Programming
2: Take me to the swirl course repository!

Selection: 1

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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: 2

| | 0%

| In this lesson, you'll learn how to examine your local workspace
| in R and begin to explore the relationship between your
| workspace and the file system of your machine.

...

|= | 3%
| Because different operating systems have different conventions
| with regards to things like file paths, the outputs of these
| commands may vary across machines.

...

|=== | 5%
| However it's important to note that R provides a common API (a
| common set of commands) for interacting with files, that way
| your code will work across different kinds of computers.

...

|==== | 8%
| Let's jump right in so you can get a feel for how these special
| functions work!

...

|====== | 10%
| Determine which directory your R session is using as its current
| working directory using getwd().

getwd()
[1] "C:/Users/kk/PortableApps/Git/home/k-allika/repos/DataScienceWithR"

| Perseverance, that's the answer.

|======= | 13%
| List all the objects in your local workspace using ls().

setwd("C:/Users/kk/PortableApps/Git/home/k-allika/repos/DataScienceWithR/swirl")

| That's not the answer I was looking for, but try again. Or, type
| info() for more options.

| Type ls() to view all the objects in your local workspace.

getwd()
[1] "C:/Users/kk/PortableApps/Git/home/k-allika/repos/DataScienceWithR/swirl"

| Nice try, but that's not exactly what I was hoping for. Try
| again. Or, type info() for more options.

| Type ls() to view all the objects in your local workspace.

ls()
[1] "my_div" "my_sqrt" "x" "y" "z"

| That's the answer I was looking for.

|========= | 15%
| Some R commands are the same as their equivalents commands on
| Linux or on a Mac. Both Linux and Mac operating systems are
| based on an operating system called Unix. It's always a good
| idea to learn more about Unix!

...

|========== | 18%
| Assign 9 to x using x <- 9.

x<-9

| Excellent work!

|============ | 21%
| Now take a look at objects that are in your workspace using
| ls().

ls()
[1] "my_div" "my_sqrt" "x" "y" "z"

| That's a job well done!

|============= | 23%
| List all the files in your working directory using list.files()
| or dir().

list.files()
character(0)

| Keep up the great work!

|=============== | 26%
| As we go through this lesson, you should be examining the help
| page for each new function. Check out the help page for
| list.files with the command ?list.files.

?list.files

| Your dedication is inspiring!

|================ | 28%
| One of the most helpful parts of any R help file is the See Also
| section. Read that section for list.files. Some of these
| functions may be used in later portions of this lesson.

...

|================== | 31%
| Using the args() function on a function name is also a handy way to see what arguments
| a function can take.

...

|=================== | 33%
| Use the args() function to determine the arguments to list.files().

?args()
args(list.files)
function (path = ".", pattern = NULL, all.files = FALSE,
full.names = FALSE, recursive = FALSE, ignore.case = FALSE,
include.dirs = FALSE, no.. = FALSE)
NULL

| You are amazing!

|==================== | 36%
| Assign the value of the current working directory to a variable called "old.dir".

old.dir=getwd()

| Not exactly. Give it another go. Or, type info() for more options.

| Type old.dir <- getwd() to assign the value of the current working directory to a
| variable called "old.dir".

old.dir<-getwd()

| You are quite good my friend!

|====================== | 38%
| We will use old.dir at the end of this lesson to move back to the place that we
| started. A lot of query functions like getwd() have the useful property that they
| return the answer to the question as a result of the function.

...

|======================= | 41%
| Use dir.create() to create a directory in the current working directory called
| "testdir".

?dir.create()
dir.create("testdir")

| Excellent work!

|========================= | 44%
| We will do all our work in this new directory and then delete it after we are done.
| This is the R analog to "Take only pictures, leave only footprints."

...

|========================== | 46%
| Set your working directory to "testdir" with the setwd() command.

setwd()<-"testdir"
Error in setwd() <- "testdir" : invalid (NULL) left side of assignment
setwd("testdir")

| Your dedication is inspiring!

|============================ | 49%
| In general, you will want your working directory to be someplace sensible, perhaps
| created for the specific project that you are working on. In fact, organizing your work
| in R packages using RStudio is an excellent option. Check out RStudio at
| http://www.rstudio.com/

...

|============================= | 51%
| Create a file in your working directory called "mytest.R" using the file.create()
| function.

?file.create()
file.create("mytest.R")
[1] TRUE

| You're the best!

|=============================== | 54%
| This should be the only file in this newly created directory. Let's check this by
| listing all the files in the current directory.

ls()
[1] "my_div" "my_sqrt" "old.dir" "x" "y" "z"

| That's not exactly what I'm looking for. Try again. Or, type info() for more options.

| list.files() shows that the directory only contains mytest.R.

dir()
[1] "mytest.R"

| Nice work!

|================================ | 56%
| Check to see if "mytest.R" exists in the working directory using the file.exists()
| function.

file.exists("mytest.R")
[1] TRUE

| Great job!

|================================== | 59%
| These sorts of functions are excessive for interactive use. But, if you are running a
| program that loops through a series of files and does some processing on each one, you
| will want to check to see that each exists before you try to process it.

...

|=================================== | 62%
| Access information about the file "mytest.R" by using file.info().

file.info("mytest.R")
size isdir mode mtime ctime atime exe
mytest.R 0 FALSE 666 2020-04-13 20:41:47 2020-04-13 20:41:47 2020-04-13 20:41:47 no

| Excellent job!

|===================================== | 64%
| You can use the $ operator --- e.g., file.info("mytest.R")$mode --- to grab specific
| items.

...

|====================================== | 67%
| Change the name of the file "mytest.R" to "mytest2.R" by using file.rename().

?file.rename()
file.rename("mytest.R","mytest2.R")
[1] TRUE

| Your dedication is inspiring!

|======================================= | 69%
| Your operating system will provide simpler tools for these sorts of tasks, but having
| the ability to manipulate files programatically is useful. You might now try to delete
| mytest.R using file.remove('mytest.R'), but that won't work since mytest.R no longer
| exists. You have already renamed it.

...

|========================================= | 72%
| Make a copy of "mytest2.R" called "mytest3.R" using file.copy().

file.copy("mytest2.R","mytest3.R")
[1] TRUE

| Keep working like that and you'll get there!

|========================================== | 74%
| You now have two files in the current directory. That may not seem very interesting.
| But what if you were working with dozens, or millions, of individual files? In that
| case, being able to programatically act on many files would be absolutely necessary.
| Don't forget that you can, temporarily, leave the lesson by typing play() and then
| return by typing nxt().

...

|============================================ | 77%
| Provide the relative path to the file "mytest3.R" by using file.path().

file.path("mytest3.R")
[1] "mytest3.R"

| Nice work!

|============================================= | 79%
| You can use file.path to construct file and directory paths that are independent of the
| operating system your R code is running on. Pass 'folder1' and 'folder2' as arguments
| to file.path to make a platform-independent pathname.

file.path('folder1','folder2')
[1] "folder1/folder2"

| You nailed it! Good job!

|=============================================== | 82%
| Take a look at the documentation for dir.create by entering ?dir.create . Notice the
| 'recursive' argument. In order to create nested directories, 'recursive' must be set to
| TRUE.

?dir.create

| Excellent job!

|================================================ | 85%
| Create a directory in the current working directory called "testdir2" and a
| subdirectory for it called "testdir3", all in one command by using dir.create() and
| file.path().

dir.create(file.path("testdir2","testdir3"),recursive = TRUE)

| That's a job well done!

|================================================== | 87%
| Go back to your original working directory using setwd(). (Recall that we created the
| variable old.dir with the full path for the orginal working directory at the start of
| these questions.)

setwd(old.dir)

| Nice work!

|=================================================== | 90%
| It is often helpful to save the settings that you had before you began an analysis and
| then go back to them at the end. This trick is often used within functions; you save,
| say, the par() settings that you started with, mess around a bunch, and then set them
| back to the original values at the end. This isn't the same as what we have done here,
| but it seems similar enough to mention.

...

|===================================================== | 92%
| After you finish this lesson delete the 'testdir' directory that you just left (and
| everything in it)

...

|====================================================== | 95%
| Take nothing but results. Leave nothing but assumptions. That sounds like 'Take nothing
| but pictures. Leave nothing but footprints.' But it makes no sense! Surely our readers
| can come up with a better motto . . .

...

|======================================================== | 97%
| In this lesson, you learned how to examine your R workspace and work with the file
| system of your machine from within R. Thanks for playing!

...

|=========================================================| 100%
| Would you like to receive credit for completing this course on Coursera.org?

1: No
2: Yes

Selection: 2
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Last updated 2020-04-13 23:26:28.635424 IST

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