rep() für wiederholte Werte

Einführung in <code>rep()</code>

# Repeat a single value
zeros <- rep(0, times = 5)
cat('Five zeros:', zeros, '
')

# Repeat a string
status <- rep('active', times = 4)
cat('Status:', status, '
')

<code>rep(x, times)</code> — gesamten Vektor wiederholen

# Repeat a vector 3 times
weekend <- c('Saturday', 'Sunday')
four_weekends <- rep(weekend, times = 4)
cat('4 weekends:', four_weekends, '
')

# Repeat numeric vector
pattern <- c(1, 2, 3)
cat('Pattern x3:', rep(pattern, times = 3), '
')

<code>rep(x, each)</code> — jedes Element wiederholen

groups <- c('A', 'B', 'C')

# times: repeats whole vector
cat('times=3:', rep(groups, times = 3), '
')
# A B C A B C A B C

# each: repeats each element before next
cat('each=3 :', rep(groups, each = 3), '
')
# A A A B B B C C C

<code>rep(x, times = c(...))</code> — variable Wiederholungen

# Different number of repeats per element
fruits <- c('apple', 'banana', 'cherry')
counts <- c(3, 1, 2)

fruit_basket <- rep(fruits, times = counts)
cat('Fruit basket:', fruit_basket, '
')
# apple apple apple banana cherry cherry

# Useful for creating category labels
cat('Length:', length(fruit_basket), '
')

<code>rep_len()</code> — auf eine feste Länge wiederholen

# Cycle through seasons to fill 12 months
seasons <- c('Spring', 'Summer', 'Autumn', 'Winter')
year_seasons <- rep_len(seasons, length.out = 12)
cat('12 months by season:', year_seasons, '
')

# Cycle through 1, 2, 3 for 10 items
rotation <- rep_len(1:3, length.out = 10)
cat('Rotation:', rotation, '
')

<code>times</code> und <code>each</code> kombinieren

# each=2 then times=3
vals <- c(1, 2)
result <- rep(vals, each = 2, times = 3)
cat('each=2, times=3:', result, '
')
# 1 1 2 2  repeated 3 times: 1 1 2 2 1 1 2 2 1 1 2 2

cat('Length:', length(result), '
')

Ausgewogene Gruppenbezeichnungen erstellen

# 5 subjects per treatment group
treatments <- c('Control', 'LowDose', 'HighDose')
n_per_group <- 5

group_labels <- rep(treatments, each = n_per_group)
cat('Group labels:', group_labels, '
')
cat('Total subjects:', length(group_labels), '
')

# Count per group
for (g in treatments) {
  cat(g, ':', sum(group_labels == g), '
')
}

Logische Werte wiederholen

# Alternating TRUE/FALSE pattern
alternate <- rep(c(TRUE, FALSE), times = 5)
cat('Alternating mask:', alternate, '
')

# Apply mask to select every other element
data_vals <- 10:19
cat('Every other value:', data_vals[alternate], '
')

# Create a block pattern: 3 TRUE then 3 FALSE
block <- rep(c(TRUE, FALSE), each = 3)
cat('Block pattern:', block, '
')

<code>rep()</code> zum Füllen von Matrizen

# Fill a 3x4 matrix with a repeating pattern
pattern <- rep(c(1, 0), times = 6)
checker <- matrix(pattern, nrow = 3, ncol = 4)
cat('Checkerboard-like matrix:
')
print(checker)

# Fill diagonal-like with rep
fill <- rep(1:4, each = 3)
cat('Repeated fill:', fill, '
')

Eine Übersichtstabelle erweitern

# Summary: grade frequencies
grades <- c('A', 'B', 'C', 'D')
frequencies <- c(5, 12, 8, 3)

# Reconstruct raw grade vector
raw_grades <- rep(grades, times = frequencies)
cat('Raw grades (', length(raw_grades), 'students):', raw_grades, '
')

# Verify frequency table
cat('Freq table:
')
print(table(raw_grades))

Zusammenfassung von <code>rep()</code>

x <- c(10, 20, 30)
cat('times=2  :', rep(x, times = 2), '
')
cat('each=2   :', rep(x, each = 2), '
')
cat('var times:', rep(x, times = c(1, 2, 3)), '
')
cat('rep_len  :', rep_len(x, 7), '
')

Kurzer Test

Rückblick: <code>rep()</code> zum Wiederholen von Werten

# Create a balanced experiment design
treatments <- c('Placebo', 'Drug_A', 'Drug_B')
subjects_per <- 4

design <- rep(treatments, each = subjects_per)
cat('Experiment design:
')
cat(design, '
')
cat('Total N:', length(design), '
')