Difference between revisions of "R/C2/Introduction-to-basics-of-R/English"
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'''Keywords: ''' Video tutorial, spoken tutorial, introduction to R, introduction to RStudio, mathematical operations, creation of vectors, sine of a vector, plotting with R | '''Keywords: ''' Video tutorial, spoken tutorial, introduction to R, introduction to RStudio, mathematical operations, creation of vectors, sine of a vector, plotting with R | ||
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|Welcome to the spoken tutorial on basics of '''R'''. | |Welcome to the spoken tutorial on basics of '''R'''. | ||
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Practice session on R, using RStudio | Practice session on R, using RStudio | ||
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I have shrunk its size quite a bit, to fit into a small screen. | I have shrunk its size quite a bit, to fit into a small screen. | ||
Latest revision as of 23:46, 4 October 2019
FOSS: R through RStudio
R version 3.0.0 (2013-04-03) and RStudio version 0.97.336
Tutorial Title: Introduction to basics of R
Author: Kannan Moudgalya
Reviewer: Neeraj Hatekar, S. Subramanian, T. Santhanam, Sanjeev Bakshi, Revathi Kasturi and others
Date: 25 August 2013
Keywords: Video tutorial, spoken tutorial, introduction to R, introduction to RStudio, mathematical operations, creation of vectors, sine of a vector, plotting with R
| Visual Cue | Narration |
|---|---|
| Slide 1
Opening slide |
Welcome to the spoken tutorial on basics of R.
I am Kannan Moudgalya. |
| Slide 2
Learning Objectives |
In this tutorial, we hope to provide a feel for R and RStudio
|
| Slide 3
Prerequisites |
|
| Slide 4
Systems Requirements |
* I am using version 3 of R
|
| Slide 5
System Requirements, ctnd. |
Let us continue with system requirements.
|
| Slide 6
A Quick Introduction to R |
Let us give a quick introduction to R:
|
| Slide 7
A Quick Introduction to RStudio |
Let us now give a quick introduction to RStudio
|
| Show http://www.rstudio.com/ide | A two minute video by the RStudio team is available here. |
| Slide 7 contd. | Let me return to the slides.
|
| Slide 8
R, RStudio web server from Aakash |
Here is a screenshot of R and RStudio on a web server, accessed from Aakash |
| Slide 9
Practice session on R, using RStudio |
Let us do a practice session on R, using RStudio |
| Show RStudio | You now see RStudio on the screen.
I have shrunk its size quite a bit, to fit into a small screen. Please use a size you are comfortable with. I have also enlarged the font size, so that the recording is clear. You do this on Windows and Linux, by pressing control and + keys together. For this tutorial, I want to maximise the size of the console of RStudio. I do this by pressing the maximise button in the console window. I also maximise the right lower window of RStudio in a similar manner. |
| 2.1 * 5 | Let me begin multiplying two numbers two point one and five.
R gives the answer in black as ten point five. |
| 2.1 * 5 /3 | I want to divide this by three.
I will recall the previous command by clicking the up arrow. What I typed earlier, namely two point one into five appears. I will divide this by three to get the answer three point five. |
| 2 + 3 | I can add two numbers. |
| a <- 2 + 3 | I can store the result in a variable using the assignment operator:
Less than symbol followed by hyphen. |
| a = 2 + 3 | One can also use an equal sign. |
| a | If I want to see what is in a variable, I just type the variable name.
In this case, I type a and see that it has five. |
| a - 0.16 | I will subtract zero point one six from a. |
| (a - 0.16) ^ 0.5 | I will raise it to the power of zero point 5.
Remember, I have to put a minus zero point one six within brackets, to get the correct answer. We get two point two, as expected. |
| Using the left and right arrows, I moved the cursor back and forth within a command. | |
| sqrt ( a - 0.16 ) | I can also carry out the same calculation using the function call, square root. |
| exp(1) | I will find the value of e by using the function call, exp.
You may have noticed, the moment I open a bracket, R automatically closes it. This eliminates errors due to unmatched brackets. So, we see the value of e above. |
| log ( exp(1)) | I can find the natural logarithm of e with the help of the log function.
The value is one, as expected. |
| log10 ( 10^5 ) | How do we find the log to the base ten?
Use the command log10. Ten to the power five. This gives the answer as five, as expected. |
| log ( 10^5 ) | What happens if I forget the ten in log10?
We get a different answer. It is easy to verify that this answer is correct for natural logarithm. Can you please suggest a method to verify this? |
| log (10^5,10)
|
There is another way to find the logarithm to the base of 10.
Give the base as the second parameter, as I do here. We get five, as expected. |
| It is easy to create vectors in R. | |
| z = seq (-1, 2, 0.5)
|
z = s e q -1 comma 2 comma 0.5
This creates a vector starting at minus one, going up to two, in increments of point five s e q denotes sequence. |
| z | Let us see the value of z. |
| We will see other ways to create vectors in another tutorial. | |
| length (z) | We can calculate the length of the vector z using the command length.
We get the result seven, as expected. |
| We will now discuss pi. | |
| pi
|
The value of pi, is stored in the variable pi, p i, which we can see now. |
| x = seq (-2*pi, 2*pi, 1) | Let us create a vector x to start from minus two pi, go up to plus two pi, in increments of one.
Please remember to put the multiply sign. |
| x | Let us see what x contains |
| y = sin(x) | Let us find the sine of this vector using sin and store it in y.
We can work directly with vectors in R, as we did above. |
| y | Let us see what y contains. |
| plot (x, y, type=”l”)
|
Let us plot sin(x) versus x, with type=L argument added.
Note that x comes first and then y. This plot starts from zero as expected, because sin of minus two pi is zero. The plot is not smooth, as there are not many points. |
| x = seq(-2*pi, 2*pi, 0.1) | Let us now get more points by lowering the increment number to point one. |
| plot(x,y,type=”l”)
|
What happens if I try to plot without recalculating y?
R will complain that the lengths are unequal. You should pause the video and confirm that the lengths are unequal. |
| y = sin(x) | Let me recalculate y. |
| plot(x, y, type=”l”) | Let me re-plot this curve.
You can see that the plot is smoother now. Please pause the video now and look at the values stored in x and y. Please confirm that these values are as per expectation. |
| length(x)
length(y) |
We see the lengths of x and y to be 126.
You should verify that these lengths are correct. You should also display the values of x and y and verify. |
| plot(x, y) | If we drop the type parameter in the previous command, we get a plot with points. |
| Press help | Let us press the help button in the right hand side window.
Let us type plot next to the lens symbol and hit return. Let us scroll. One can see different choices for the type parameter. |
| We have come to the end of this tutorial. | |
| Slide 10
Low cost books on R |
Let us see a few low cost books on R. |
| Slide 11
Summary
|
In this tutorial we learnt about
|
| Slide 12
Assignment |
We now suggest an assignment
|
| Slide 13
About the Spoken Tutorial Project
|
This video summarises the Spoken Tutorial project.
If you do not have good bandwidth, you may download and watch it. |
| Slide 14
Spoken Tutorial Workshops |
We conduct workshops using Spoken Tutorials.
Give Certificates. Please contact us. |
| Slide 15
Acknowledgements |
The Spoken Tutorial project is funded by NMEICT, MHRD, Govt. of India |
| Slide 16 Thanks | Thanks for joining, goodbye |
