Základné operácie v R - Malé cvičenia

Author

s

Published

January 1, 2026

Globálne nastavenie Chunkov

Code
knitr::opts_chunk$set(
  echo = TRUE,
  message = FALSE,
  warning = FALSE
)

Skaláre (jednočíselné hodnoty)

Malé cvičenie

Code
(10^3 + 50) / 5
[1] 210
Code
round(15.789)
[1] 16

Text

Malé cvičenie

Code
meno <- "Jan"
priezvisko <- "Hrasko"
cele_meno <- paste(meno, priezvisko)
cele_meno
[1] "Jan Hrasko"
Code
nchar(cele_meno)
[1] 10

Logické hodnoty a premenné

Malé cvičenie

Code
x <- 25
(x > 10) & (x <= 30)
[1] TRUE
Code
"jablko" != "hruska"
[1] TRUE

Numerické vektory

Malé cvičenie

Code
v <- 1:15
v_vyber <- v[v > 10]
v_vyber
[1] 11 12 13 14 15
Code
sum(v_vyber)
[1] 65

Matice

Malé cvičenie

Code
mat <- matrix(1:16, nrow = 4, byrow = TRUE)
mat
     [,1] [,2] [,3] [,4]
[1,]    1    2    3    4
[2,]    5    6    7    8
[3,]    9   10   11   12
[4,]   13   14   15   16
Code
rowSums(mat)
[1] 10 26 42 58
Code
mat %*% t(mat)
     [,1] [,2] [,3] [,4]
[1,]   30   70  110  150
[2,]   70  174  278  382
[3,]  110  278  446  614
[4,]  150  382  614  846

Vlastné čísla a vlastné vektory matíc

Malé cvičenie

Code
cov_matrix <- matrix(c(
  4, 2, 1,
  2, 3, 1,
  1, 1, 2
), nrow = 3, byrow = TRUE)

eig_cov <- eigen(cov_matrix, symmetric = TRUE)

eig_cov$values
[1] 6.048917 1.643104 1.307979
Code
eig_cov$vectors
           [,1]       [,2]       [,3]
[1,] -0.7369762  0.5910090  0.3279853
[2,] -0.5910090 -0.3279853 -0.7369762
[3,] -0.3279853 -0.7369762  0.5910090