### Spojovani retezcu

paste("The value of pi:", pi)

paste("I", "love", "R", sep = "-")

paste("X", 1:5, sep = ".")

paste(1:3, c("!", "?", "+"), sep = "")
paste(1:3, c("!", "?", "+"), sep = "", collapse = "")


cat(my_string)
cat(my_string, "with R")
cat(my_string, "with R", sep = " =) ")

cat(1:10, sep = "-")

cat(month.name[1:4], sep = " ")

cat("Loooooooooong strings", "can be displayed", "in a nice format","by using the 'fill' argument")

cat(my_string, "with R", file = "output.txt")


#####

my_string = "programming with data is fun"
print(my_string)
print(my_string, quote = FALSE)

noquote(my_string)

no_quotes = noquote(c("some", "quoted", "text", "!%^(&="))
no_quotes
no_quotes[2:3]


##### Format retezce #######

format(13.7)
format(13.12345678)
format(13.7, nsmall = 3)


format(c(6, 13.1), digits = 2)
format(c(6, 13.1), digits = 2, nsmall = 1)
format(1/1:5, digits = 2)
format(format(1/1:5, digits = 2), width = 6, justify = "c")

format(c("A", "BB", "CCC"), width = 5, justify = "centre")
format(c("A", "BB", "CCC"), width = 5, justify = "left")
format(c("A", "BB", "CCC"), width = 5, justify = "right")
format(c("A", "BB", "CCC"), width = 5, justify = "none")

format(123456789, big.mark = ",")


# '%f' indicates 'fixed point' decimal notation
sprintf("%f", pi)
# decimal notation with 3 decimal digits
sprintf("%.3f", pi)
# 1 integer and 0 decimal digits
sprintf("%1.0f", pi)
# decimal notation with 3 decimal digits
sprintf("%5.1f", pi)
sprintf("%05.1f", pi)
# print with sign (positive)
sprintf("%+f", pi)
# prefix a space
sprintf("% f", pi)
# left adjustment
sprintf("%-10f", pi)
# exponential decimal notation 'e'
sprintf("%e", pi)
# exponential decimal notation 'E'
sprintf("%E", pi)
# number of significant digits (6 by default)
sprintf("%g", pi)


#####################

toString(17.04)
toString(c(17.04, 1978))
toString(c("Bonjour", 123, TRUE, NA, log(exp(1))))

toString(c("one", "two", "3333333333"), width = 8)
toString(c("one", "two", "3333333333"), width = 12)


#####################

length("How many characters?")
length(c("How", "many", "characters?"))

nchar("How many characters?")
nchar(c("How", "many", "characters?"))


# to lower case
tolower(c("aLL ChaRacterS in LoweR caSe", "ABCDE"))
casefold("aLL ChaRacterS in LoweR caSe")

# to upper case
toupper(c("All ChaRacterS in Upper Case", "abcde"))
casefold("All ChaRacterS in Upper Case", upper = TRUE)


# replace 'a' by 'A'
chartr("a", "A", "This is a boring string")
chartr("ai", "X", "This is a bad example")

crazy = c("Here's to the crazy ones", "The misfits", "The rebels")
chartr("aei", "#!?", crazy)

# extract 'bcd'
substr("abcdef", start=2, stop=4)

# replace 2nd letter with hash symbol
x = c("may", "the", "force", "be", "with", "you")
substr(x, 2, 2) <- "#"
x

# replace 2nd and 3rd letters with happy face
y = c("may", "the", "force", "be", "with", "you")
substr(y, 2, 3) <- ":)"
y

# replacement with recycling
z = c("may", "the", "force", "be", "with", "you")
substr(z, 2, 3) <- c("#", "@")
z


substring("ABCDEF", 2, 4)

# extract each letter
substring("ABCDEF", 1:6, 1:6)

# multiple replacement with recycling
text = c("more", "emotions", "are", "better", "than", "less")
substring(text, 1:3) <- c(" ", "zzz")
text


set11 = c("today", "produced", "example", "beautiful", "a", "nicely")
# sort (decreasing order)
sort(set11)
# sort (increasing order)
sort(set11, decreasing = TRUE)


###################################################

str = "Splitting sentence into words"
strsplit(str, " ")
unlist(strsplit(str, " "))

a <- "Alabama-Alaska-Arizona-Arkansas-California"
strsplit(a, split = "-")

#######################################################

myStrings <- paste(1:3, month.name, sep = ". ")
myStrings

# Is a pattern present (returns a logical vector)?
grepl("ember", myStrings)

# In which elements is a pattern present (returns indices)?
grep("ember", myStrings)

# In which elements is a pattern present (returns the values)?
grep("ember", myStrings, value = TRUE)


#######################################################


startsWith(month.name, "J")

endsWith(month.name, "ember")


#######################################################

substr(month.name, 1, 3)

substring(month.name, 1, 3)

strtrim(month.name, 3)



trimws(" This has trailing spaces.  ")

#######################################################


library(stringr)

str_c("May", "The", "Force", "Be", "With", "You")

# removing zero length objects
paste("May", "The", "Force", NULL, "Be", "With", "You", character(0))
str_c("May", "The", "Force", NULL, "Be", "With", "You", character(0))

str_c("May", "The", "Force", "Be", "With", "You", sep = "_")
str_join("May", "The", "Force", "Be", "With", "You", sep = "-") # analogicka fce k predchozi


some_text = c("one", "two", "three", NA, "five")
nchar(some_text)
str_length(some_text)


# some factor
some_factor = factor(c(1, 1, 1, 2, 2, 2), labels = c("good", "bad"))
some_factor

nchar(some_factor)
str_length(some_factor)


lorem = "Lorem Ipsum"
substring(lorem, first = 1, last = 5)
str_sub(lorem, start = 1, end = 5)

str_sub("adios", 1:3)

resto = c("brasserie", "bistrot", "creperie", "bouchon")
substring(resto, first = -4, last = -1)
str_sub(resto, start = -4, end = -1)

str_sub(lorem, seq_len(nchar(lorem)))
substring(lorem, seq_len(nchar(lorem)))

str_sub(lorem, -seq_len(nchar(lorem)))
substring(lorem, -seq_len(nchar(lorem)))

lorem = "Lorem Ipsum"
str_sub(lorem, 1, 5) <- "Nullam"
lorem

lorem = "Lorem Ipsum"
str_sub(lorem, -1) <- "Nullam"
lorem

lorem = "Lorem Ipsum"
str_sub(lorem, c(1, 7), c(5, 8)) <- c("Nullam", "Enim")
lorem


##################

str_dup("hola", 3)

str_dup("adios", 1:3)


words = c("lorem", "ipsum", "dolor", "sit", "amet")

str_dup(words, 2)

str_dup(words, 1:5)


##################

str_pad("hola", width = 7)

str_pad("adios", width = 7, side = "both")

str_pad("hashtag", width = 8, pad = "#")

str_pad("hashtag", width = 9, side = "both", pad = "-")


###################

bad_text = c("This", " example ", "has several   ", "   whitespaces ")

str_trim(bad_text, side = "left")

str_trim(bad_text, side = "right")

str_trim(bad_text, side = "both")


###################

change = c("Be the change", "you want to be")

# extract first word
word(change, 1)

# extract second word
word(change, 2)

# extract last word
word(change, -1)

# extract all but the first words
word(change, 2, -1)


#####################


library(stringi)

stri_reverse("dna")


library(Biostrings)

str_rev("dna")