Matrices

 

These exercises are about the matrices sections of Introduction to R.

These exercises cover the matrices sections of Introduction to R.

Exercise 1

• Create a matrix containing information on gene names Gene_1, Gene_2, Gene_3,Gene_4 expression values 1000, 3000, 10000, 12000 and gene lengths 100, 3000, 200, 1000

##        expression geneLengths
## Gene_1       1000         100
## Gene_2       3000        3000
## Gene_3      10000         200
## Gene_4      12000        1000

• Update the matrix to contain the expression over the gene length for all genes (Length normalised expression) as final column.

HINT - We calculated LNE before in vectors exercises’ bonus question

##        expression geneLengths lne
## Gene_1       1000         100  10
## Gene_2       3000        3000   1
## Gene_3      10000         200  50
## Gene_4      12000        1000  12

• Create a smaller matrix containing genes longer than 200

##        expression geneLengths lne
## Gene_2       3000        3000   1
## Gene_4      12000        1000  12

• Create a smaller matrix with just expression and lne columns containing genes longer than 200 and expression greater than 300.

##        expression lne
## Gene_2       3000   1
## Gene_4      12000  12

Bonus Question

- Calculate the sum of expression and length columns for only genes with length > 100.

##  expression geneLengths 
##       25000        4200