R Notebook

This is an R Markdown Notebook. When you execute code within the notebook, the results appear beneath the code.

Try executing this chunk by clicking the Run button within the chunk or by placing your cursor inside it and pressing Ctrl+Shift+Enter.

plot(cars)

Add a new chunk by clicking the Insert Chunk button on the toolbar or by pressing Ctrl+Alt+I.

When you save the notebook, an HTML file containing the code and output will be saved alongside it (click the Preview button or press Ctrl+Shift+K to preview the HTML file).

The preview shows you a rendered HTML copy of the contents of the editor. Consequently, unlike Knit, Preview does not run any R code chunks. Instead, the output of the chunk when it was last run in the editor is displayed. INICIO - Feb 8th, 2019

#matrices

A = matrix(c(1:8), nrow=4, ncol=2, byrow= T)
A

dim(A)
#Filas, Columnas

Transpose

t(A)

Otra matriz, B. Determinante de una matriz, debe ser matriz de NxN (cuadrada)

B= matrix(c(1, -1,2,3,2,1,0,1,3,-1, 1, 2,2,-1,0, 1), nrow=4, ncol = 4, byrow = T)
B
paste('Determinante', det(B))

Diagonal

diag(B)

Identidad

mtrx.Ident = diag(rep(1,4))
mtrx.Ident

Multiplicacion de matrices… Usar %*%

B%*%mtrx.Ident

Suma de Filas

rowSums(A)
colMeans(A)
rowMeans(A)

Combinar MAtrices

cbind(A, B)
#rbind(A, B) gives error

DataFrames

Subsetting

names(df.ex)

[1] "x" "y" "z"

df.ey <- df.ex[df.ex$x >= 50, ]
df.ey

‘Apply’ function. 1 o 2 define si recorre x, y

apply(df.ex, 1, sum)

 [1] 128 175 249 170 194  76 203 212 175 282 133  58 161 131 143 157 106 135  47  93 161 244  98  97 134