Know more about data

## Fruit data totally have 80 fruit names and these are individual srings in a vector

## Number of sentences we totally have is  720 and these are individual srings in a vector

Finding Length of String

Length of string can be obtained using stringr::str_length(string name) function

sample_fruit=fruit[c(8,16,24,32)]
sample_fruit

## [1] "blackcurrant" "cherry"       "damson"       "goji berry"

str_length(sample_fruit)

## [1] 12  6  6 10

Casefolding string

In some situations we may wish to process our string data in a way to either convert them all to upper or lower case. This can be done with casefold(), we give input vector and upper=T/F argument is used to specify whether we wish to change it to upper case or lower case. By default it taked the argument as upper=F

#To uppercase
f_upper=casefold(head(fruit),upper=T)
print(f_upper)

## [1] "APPLE"       "APRICOT"     "AVOCADO"     "BANANA"      "BELL PEPPER"
## [6] "BILBERRY"

#To lowercase
f_lower=casefold(head(fruit),upper=F)
print(f_lower)

## [1] "apple"       "apricot"     "avocado"     "banana"      "bell pepper"
## [6] "bilberry"

In some scenario we wish to capitalize each word in a string and this can be done using stringr::str_to_title(), we specify input vector and locale is used for representing string in other language,default is English

# Sample data
sample=sentences[c(2,3)]
print(sample)

## [1] "Glue the sheet to the dark blue background."
## [2] "It's easy to tell the depth of a well."

#Each word capitalized
cap=str_to_title(sample, locale = "en")
print(cap)

## [1] "Glue The Sheet To The Dark Blue Background."
## [2] "It's Easy To Tell The Depth Of A Well."

# setting locale as Turkish
str_to_title("it is invariable",locale="tr")

## [1] "It Is Invariable"

Capitalizing a sentence can be done using stringr::str_to_sentence()

string_2=casefold(sentences[c(19,40)])
string_2

## [1] "the salt breeze came across from the sea."
## [2] "what joy there is in living."

sent=str_to_sentence(string_2)
print(sent)

## [1] "The salt breeze came across from the sea."
## [2] "What joy there is in living."

Trimming white spaces

White spaces in a string data can be removed using trimws(), which argument is used to specify whether we wish to trim right side or left side or both sides.

#text with blank line in the beginning
text="   
    
    
There are no secrets to success. It is the result of preparation, hard work, and learning from failure.                                 "
#Original text
print(text)

## [1] "   \n    \n    \nThere are no secrets to success. It is the result of preparation, hard work, and learning from failure.                                 "

#By default it trims both sides
trimws(text)

## [1] "There are no secrets to success. It is the result of preparation, hard work, and learning from failure."

#we can specify with lesser letters also for specifying which side to trim
trimws(text,which="l")#for left side

## [1] "There are no secrets to success. It is the result of preparation, hard work, and learning from failure.                                 "

trimws(text,"ri")#for right side

## [1] "   \n    \n    \nThere are no secrets to success. It is the result of preparation, hard work, and learning from failure."

trimws(text,"bot")#for both sides

## [1] "There are no secrets to success. It is the result of preparation, hard work, and learning from failure."

Truncating a String

A string can be truncated in to specified width (minimum width is 5). This can be done using stringr::str_trunc(), we need to give the string as input and width argument is used to specify width of resulting string and side argument is used to specify which side to truncate i.e right, left or center.An useful application of this can be found where we are asked to enter recovery email for security reasons while logging in to mail.

string1=c("person1useraccount@mail.com","user2account@mail.com")
#center truncate
str_trunc(string1,width=max(6,round(nchar(string1)/2)),side="center")

## [1] "person...l.com" "user2a...l.com"

string_2=sentences[c(1,55)];string_2

## [1] "The birch canoe slid on the smooth planks."
## [2] "A saw is a tool used for making boards."

#Right truncate
str_trunc(string_2,width=max(6,round(nchar(string_2)/2)),side="right")

## [1] "The birch canoe sl..." "A saw is a tool us..."

#Left truncate
str_trunc(string_2,width=max(6,round(nchar(string_2)/2)),side="left")

## [1] "...the smooth planks." "...for making boards."

To abbreviate strings

Sentences can be abbreviated with the help of abbreviate() function.
This function takes the string and gives back the abbreviation based on number of minimum characters we specify (by default it is 4 ) and considers mostly first letters of words which appears after space and subsequent letters from other words are taken hierarchically if needed. We use minlength argument to specify minimum length of the abbreviation. For any specified minlength it takes all the first letters of words and length of abbreviation is always greater than or equal to number of words. use.classes argument is used to mention whether hierarchically lower case letters should be removed first or not

some_statements=c("Rolling on floor laughing","one"," Be right back","In my opinion","To be announced","as soon as possible")
abbreviation=abbreviate(some_statements,minlength=1,use.classes = F)
as.data.frame(abbreviation)->y

kbl(y,caption="abbreviate example") %>%
  kable_styling(bootstrap_options = "striped", full_width = F, position = "left")

To Join multiple string objects to single string

With the paste()/paste0() function we can merge several strings in a vector in to one string. We can use collapse argument within the function for this purpose

words=fruit[c(1,11,43,17,47)];words

## [1] "apple"        "boysenberry"  "kumquat"      "chili pepper" "lychee"

paste0(words,collapse = " ")

## [1] "apple boysenberry kumquat chili pepper lychee"

joining multiple individual strings in to single string can be done using sep argument in the function

x2="This "
x3=" is "
x4=" an "
x5=" example"
paste(x2,x3,x4,x5,sep = "_")

## [1] "This _ is _ an _ example"

paste(x2,x3,x4,x5,sep = "|")

## [1] "This | is | an | example"

Getting substring

When we are interested in some part of a string we use substr(string,start,stop) function to slice it from original using position. We are giving start and end positions of the characters as arguments in the function.

#Preparing long string
long_string=paste0(sentences[c(1,44,25,66)],collapse = " ")
long_string

## [1] "The birch canoe slid on the smooth planks. The wide road shimmered in the hot sun. The beauty of the view stunned the young boy. Cars and busses stalled in snow drifts."

# Getting substring
substr(long_string,1,42)

## [1] "The birch canoe slid on the smooth planks."

Splitting string in to list

Sometimes a long string needs to be split into parts so that each word of it can be accessed for particular purpose. strsplit(x,split="character used to split") function is used to break a single string in to list of strings. split is used tospecify which character we use for splitting

# For splitting we can use either single character or more
long_string=paste0(sentences[c(1,44,25,66)],collapse = " ");long_string

## [1] "The birch canoe slid on the smooth planks. The wide road shimmered in the hot sun. The beauty of the view stunned the young boy. Cars and busses stalled in snow drifts."

sample_2 =strsplit(long_string,split="\\.")# using escape sequence for .
# using /
strsplit("20/abc 56/90t/1","/")

## [[1]]
## [1] "20"     "abc 56" "90t"    "1"

#using B
strsplit("GeniusBisBpatience.","B")

## [[1]]
## [1] "Genius"    "is"        "patience."

#using 1
strsplit("It, is` the weight,1 not numbers of experiments that is to be regarded","1"
)

## [[1]]
## [1] "It, is` the weight,"                               
## [2] " not numbers of experiments that is to be regarded"

List to Vector of strings

Once we obtain the list we can convert it to iterable form called as Character vector using unlist(list_name)

#list to vector
unlist(sample_2)

## [1] "The birch canoe slid on the smooth planks"    
## [2] " The wide road shimmered in the hot sun"      
## [3] " The beauty of the view stunned the young boy"
## [4] " Cars and busses stalled in snow drifts"

Set Operations

R has dedicated functions for performing set operations on two given “character” vectors. Let’s see some of them below

#Set union
set=fruit[c(1,5,9,24)];set

## [1] "apple"        "bell pepper"  "blood orange" "damson"

set1=fruit[c(1,2,10,25,9)];set1

## [1] "apple"        "apricot"      "blueberry"    "date"         "blood orange"

union(set,set1)

## [1] "apple"        "bell pepper"  "blood orange" "damson"       "apricot"     
## [6] "blueberry"    "date"

#set intersection
set

## [1] "apple"        "bell pepper"  "blood orange" "damson"

set1

## [1] "apple"        "apricot"      "blueberry"    "date"         "blood orange"

intersect(set,set1)

## [1] "apple"        "blood orange"

# two character vectors
set1 <- c("some", "random", "few", "words")
set2 <- c("some", "many", "none", "few")

# difference between set5 and set6
setdiff(set1, set2)

## [1] "random" "words"

# Equality without order
# three character vectors
set3 <- c("some", "random", "strings")
set4 <- c("thor", "bean", "teddy", "few")
set5 <- c("strings", "random", "some")

# Equality of set 3 and 4
setequal(set3, set4)

## [1] FALSE

#Equality of set 3 and 5 
setequal(set3, set5)

## [1] TRUE

set3 <- c("some", "random", "strings")

set5 <- c("strings", "random", "some")

# Equality with Order
# set3 identical to set3?
identical(set3, set3)

## [1] TRUE

# set3 identical to set5?
identical(set3, set5)

## [1] FALSE

# three vectors
set10 <- c("some", "stuff", "to", "play", "with")
element_1 <- "play"
element_2 <- "crazy"

# element 1 in set10?
is.element(element_1, set10)

## [1] TRUE

# element 2 in set10?
is.element(element_2, set10)

## [1] FALSE

# element 1 in set10?
element_1 %in% set10

## [1] TRUE

Sorting

The function sort() allows you to sort the elements of a vector, either in increasing order (by default) or in decreasing order using the argument decreasing.
NOTE : Numbers are always before alphabets

# Soting Character vector(default is increasing)
set11 = c("today", "produced", "example", "beautiful", "a", "nicely","10000")

# sort (increasing order)
sort(set11)

## [1] "10000"     "a"         "beautiful" "example"   "nicely"    "produced" 
## [7] "today"

# sort (decreasing order)
sort(set11, decreasing = TRUE)

## [1] "today"     "produced"  "nicely"    "example"   "beautiful" "a"        
## [7] "10000"

Finding Existence of pattern

Finding Existence of word in a string is useful since keywords play major role in search algorithms.
Let’s take3 sentences randomly from our data

s=sentences[c(3,24,221)]
# Let us see all the three random sentences we have taken.
print(s)

## [1] "It's easy to tell the depth of a well." 
## [2] "The swan dive was far short of perfect."
## [3] "A pencil with black lead writes best."

Now if we wish to know whether ‘the’ exists in the sentences we can use str_detect() this returns Boolean values indicating presence

str_detect(s, "the")

## [1]  TRUE FALSE FALSE

so the pattern “the” exists only in 1st sentence of our word as per the function.
The word ‘the’ exists in 1st and 2nd sentences but in 2nd sentence first letter T is capitalized. To detect the pattern ignoring the case whether upper or lower we can use ignore_case argument.

str_detect(s,regex( "the",ignore_case=T))

## [1]  TRUE  TRUE FALSE

Finding a pattern’s position of occurence in vector of strings

grep() This function searches for matches of certain character pattern in a vector of character strings and returns the indices that yield a match.The function searches for matches of certain character pattern in a vector of character strings and returns a logical vector indicating which elements of the vector contained a match.

#getting position of occurence
grep("s1",c("science group s1","science group","another group s1"))

## [1] 1 3

#getting boolean values indication presence
grepl("s1",c("science group s1","science group","another group s1"))

## [1]  TRUE FALSE  TRUE

Counting number of times pattern occurs

We can get the count which indicates number of times a pattern occurs in a string using stringr::str_count()

string=c("s1 science group s1","science group","another group s1");string

## [1] "s1 science group s1" "science group"       "another group s1"

str_count(string, "s1")

## [1] 2 0 1

Find and replace

gsub(pattern, replacement, x ), This command is used to find a pattern and replace it in a string. In this function also we can use ignore.case argument to consider upper and lower case strings as same

fr="Data is an interesting field to work with"
gsub("data","Data Science",fr,ignore.case=T)

## [1] "Data Science is an interesting field to work with"

gsub("data ","Data Science",fr)

## [1] "Data is an interesting field to work with"

Extracting word using its position

stringr::word() We can extract a part of sentence by position of words in it using above function

sentences1 <- sentences[c(12,15,66)];sentences1

## [1] "A rod is used to catch pink salmon."    
## [2] "Help the woman get back to her feet."   
## [3] "Cars and busses stalled in snow drifts."

#Extracting words from first word to last word
word(sentences1,start= 1,end=-1,sep=" ")

## [1] "A rod is used to catch pink salmon."    
## [2] "Help the woman get back to her feet."   
## [3] "Cars and busses stalled in snow drifts."

#Extracting till last word starting from first word for first element second word from second element and so on 
word(sentences1,start=1:3,end=-1,sep=" ")

## [1] "A rod is used to catch pink salmon." "the woman get back to her feet."    
## [3] "busses stalled in snow drifts."

We can use a wide range of separators based on scenario to extract words

statement="To, improve, is, to, change, so, to, be, perfect, is, to, change, often"
word(statement,4,sep=fixed(','))

## [1] " to"