Presentations

1
Presentations

• Golub paper on AML-ALL classification, Sept 11,
  by Yichun, Peggy, Cecile
• Calvano paper on gene-network, Sept 25, by Jing,
  Chenara, Cheng
• Ureta-Vidal paper on Comparative genomics, Oct 9,
  by Tze Howe, Zachary, Maria

2
R continued

• vector
• z lt- 09
• z2lt-5

3
factor

• state lt- c("tas", "sa", "qld", "nsw", "nsw",
  "nt", "wa", "wa", "qld", "vic", "nsw", "vic",
  "qld", "qld", "sa", "tas", "sa", "nt", "wa",
  "vic", "qld", "nsw", "nsw", "wa", "sa", "act",
  "nsw", "vic", "vic", "act")
• statef lt- factor(state)
• incomes lt- c(60, 49, 40, 61, 64, 60, 59, 54, 62,
  69, 70, 42, 56, 61, 61, 61, 58, 51, 48, 65, 49,
  49, 41, 48, 52, 46, 59, 46, 58, 43)
• incmeans lt- tapply(incomes, statef, mean)

4
array

• Creating an array
• Z lt- array(data_vector, dim_vector)
• xlt-1100
• matlt-array(x,c(10,10))
• matrix transposition t(mat)

5
array cont.

• x lt- array(120, dimc(4,5)) Generate a 4 by 5
  array.
• i lt- array(c(13,31), dimc(3,2))
• Array indexingxixi lt- 0

6
Matrix product

• Let A and B be two matrices
• A B element by element multiplication
• A B matrix multiplication

7
Distance

• i lt- array(c(13,31), dimc(3,2))
• dist(i, method "manhattan")
• dist(i, method "euclidean")

8
Homework

• Read Introduction to R to 5.7.2
• Gentleman book 12.3.3

9
Linear equations and inversion

• Solving linear equations is the inverse of matrix
  multiplication.
• b lt- A x only A and b are given, the vector
  x is the solution of that linear equation system.
  
• solve(A,b) solves the system, returning x
• Formally x A-1 b where A-1 denotes
  the inverse of A, which can be computed by
  solve(A)