We've updated our privacy policy. Click here to review the details. Tap here to review the details.

Successfully reported this slideshow.

Your SlideShare is downloading.
×

Activate your 30 day free trial to unlock unlimited reading.

Activate your 30 day free trial to continue reading.

Top clipped slide

1 of 13
Ad

Download to read offline

R, Python

Asst Professor @ Avanthi PG college

R, Python

- 1. Vector Maths Arithmetic operations of vectors are performed member-by-member, i.e., member wise. For example, suppose we have two vectors a and b. > a = c(1, 3, 5, 7) > b = c(1, 2, 4, 8) Then, if we multiply a by 5, we would get a vector with each of its members multiplied by 5. > 5 * a [1] 5 15 25 35 And if we add a and b together, the sum would be a vector whose members are the sum of the corresponding members from a and b. > a + b [1] 2 5 9 15 Similarly for subtraction, multiplication and division, we get new vectors via memberwise operations. > a - b [1] 0 1 1 -1 > a * b [1] 1 6 20 56 > a / b [1] 1.000 1.500 1.250 0.875
- 2. Recycling Rule • If two vectors are of unequal length, the shorter one will be recycled in order to match the longer vector. For example, the following vectors u and v have different lengths, and their sum is computed by recycling values of the shorter vector u. • > u = c(10, 20, 30) > v = c(1, 2, 3, 4, 5, 6, 7, 8, 9) > u + v [1] 11 22 33 14 25 36 17 28 39
- 3. Vector Index • Vector Index • We retrieve values in a vector by declaring an index inside a single square bracket "[]" operator. • For example, the following shows how to retrieve a vector member. Since the vector index is 1-based, we use the index position 3 for retrieving the third member. • > s = c("aa", "bb", "cc", "dd", "ee") > s[3] [1] "cc"
- 4. Negative Index • If the index is negative, it would strip the member whose position has the same absolute value as the negative index. • For example, the following creates a vector slice with the third member removed. • > s[-3] [1] "aa" "bb" "dd" "ee" • Out-of-Range Index • If an index is out-of-range, a missing value will be reported via the symbol NA. • > s[10] [1] NA
- 5. Matrix • A matrix is a collection of data elements arranged in a two-dimensional rectangular layout. The following is an example of a matrix with 2 rows and 3 columns. • We reproduce a memory representation of the matrix in R with the matrix function. The data elements must be of the same basic type.
- 6. • > A = matrix( + c(2, 4, 3, 1, 5, 7), # the data elements + nrow=2, # number of rows + ncol=3, # number of columns + byrow = T • A # print the matrix [,1] [,2] [,3] [1,] 2 4 3 [2,] 1 5 7RUE) # fill matrix by rows
- 7. • An element at the mth row, nth column of A can be accessed by the expression A[m, n]. • > A[2, 3] # element at 2nd row, 3rd column [1] 7 • The entire mth row A can be extracted as A[m, ]. • > A[2, ] # the 2nd row [1] 1 5 7 • Similarly, the entire nth column A can be extracted as A[ ,n]. • > A[ ,3] # the 3rd column [1] 3 7 • We can also extract more than one rows or columns at a time. • > A[ ,c(1,3)] # the 1st and 3rd columns [,1] [,2] [1,] 2 3 [2,] 1 7
- 8. Matrix Addition & Subtraction • # Create two 2x3 matrices. • matrix1 <- matrix(c(3, 9, -1, 4, 2, 6), nrow = 2) print(matrix1) • matrix2 <- matrix(c(5, 2, 0, 9, 3, 4), nrow = 2) print(matrix2) • # Add the matrices. • result <- matrix1 + matrix2 • cat("Result of addition","n") • print(result) • # Subtract the matrices • result <- matrix1 - matrix2 • cat("Result of subtraction","n") print(result)
- 9. Matrix Multiplication & Division • # Create two 2x3 matrices. • matrix1 <- matrix(c(3, 9, -1, 4, 2, 6), nrow = 2) print(matrix1) • matrix2 <- matrix(c(5, 2, 0, 9, 3, 4), nrow = 2) print(matrix2 • # Multiply the matrices. • result <- matrix1 * matrix2 • cat("Result of multiplication","n") print(result))
- 10. • # Divide the matrices • result <- matrix1 / matrix2 • cat("Result of division","n") • print(result)
- 11. Matrix Access • Create a Matrix • x<-1:12 • Print(x) • Mat<-matrix(x,3,4) • Access third row of an existing matrix • Mat[3,] • Second column • Mat[,2] • Access second and third column • Mat[,2,3]
- 12. Contour plot • Contour plots are used to show 3- dimensional data on a 2-dimensional surface. The most common example of a contour plot is a topographical map, which shows latitude and longitude on the y and x axis, and elevation overlaid with contours. Colours can also be used on the map surface to further highlight the contours
- 13. • Create a matrix, mat which is 9 rows and 9 columns with all values are 1 • Mat<-matrix(1,9,9) • Print(mat) • Replace a value of 3rd row 3rd column • Mat[3,3]<-0 • Contour(mat) • Create a 3D perspective plot with persp(). It provides 3D wireframe plot • Persp(mat) • R includes some pre defined data sets • Volcano, which is 3D map dormant of New Zealand • Contour(volcano) • Heat map • Image(volcano)

No public clipboards found for this slide

You just clipped your first slide!

Clipping is a handy way to collect important slides you want to go back to later. Now customize the name of a clipboard to store your clips.Hate ads?

Enjoy access to millions of presentations, documents, ebooks, audiobooks, magazines, and more **ad-free.**

The SlideShare family just got bigger. Enjoy access to millions of ebooks, audiobooks, magazines, and more from Scribd.

Cancel anytime.
Be the first to like this

Total views

173

On SlideShare

0

From Embeds

0

Number of Embeds

4

Unlimited Reading

Learn faster and smarter from top experts

Unlimited Downloading

Download to take your learnings offline and on the go

You also get free access to Scribd!

Instant access to millions of ebooks, audiobooks, magazines, podcasts and more.

Read and listen offline with any device.

Free access to premium services like Tuneln, Mubi and more.

We’ve updated our privacy policy so that we are compliant with changing global privacy regulations and to provide you with insight into the limited ways in which we use your data.

You can read the details below. By accepting, you agree to the updated privacy policy.

Thank you!

We've encountered a problem, please try again.