30-seconds-of-r-code

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30 seconds of r-code

Base-R expressions to get some basic things done in less than 30 seconds.

Related:

• Javasrcript
• Python
• css

Table of contents

• Creating a 10*10 matrix with random numbers
• Matrix to Dataframe
• Scatter Plot to understand Correlation
• Correlation Matrix
• Dimension of a dataframe
• Transposing a dataframe
• Group Count
• Grouped Airthmetic Operation
• New Function Creationg (String Concatenation)
• Current Time and Date
• Boolean to Integer Typecasting
• Counting Number of Characters in a string
• Counting Number of Words in a string
• Length of each word in a string
• Extracting Words starting with 's' in a string
• String to Lower Case and to Upper Case
• String Find and Replace

Creating a 10*10 matrix with random numbers

set.seed(123)
new_matrix <- matrix(rnorm(100), nrow = 10, ncol = 10)
new_matrix

Matrix to Dataframe

set.seed(123)
new_matrix <- matrix(rnorm(100), nrow = 10, ncol = 10)
new_df <- data.frame(new_matrix)
names(new_df) <- 1:10
new_df

Scatter Plot to understand Correlation

plot(iris[,1:4])

Correlation Matrix

cor(iris[,1:4])

Dimension of a dataframe

dim(iris)

1. 150
2. 5

Transposing a dataframe

t(iris)

Group Count

table(iris$Species)

    setosa versicolor  virginica 
        50         50         50 

Grouped Airthmetic Operation

aggregate(Sepal.Width ~ Species, iris,FUN=mean) 
aggregate(Sepal.Width ~ Species, iris,FUN=max)

New Function Creationg (String Concatenation)

my_name_is <- function(name) {paste('My name is ',name)} #declaration
my_name_is('Optimus Prime') #Function Call

'My name is Optimus Prime'

Current Time and Date

Sys.Date()
Sys.time()

2017-12-12

[1] "2017-12-12 20:17:28 IST"

Boolean to Integer Typecasting

bool_vector <- c(T,F,T,T)
+bool_vector

1. 1
2. 0
3. 1
4. 1

Counting Number of Characters in a string

sentence <- 'This is a sample sentence whose length I am trying to find'
nchar(sentence)

58

Counting Number of Words in a string

sentence <- 'This is a sample sentence whose length I am trying to find'
length(unlist(strsplit(sentence,' ')))

12

Length of each word in a string

sentence <- 'This is a sample sentence whose length I am trying to find'
data.frame(words = unlist(strsplit(sentence,' ')), length = nchar(unlist(strsplit(sentence,' '))))

Extracting Words starting with 's' in a string

sentence <- 'This is a sample sentence whose length I am trying to find'
unlist(lapply(unlist(strsplit(sentence, ' ')),function(x){if(startsWith(x,'s')){x}}))

1. 'sample'
2. 'sentence'

String to Lower Case and to Upper Case

sentence <- 'This is a sample sentence whose length I am trying to find'
casefold(sentence,F)
casefold(sentence,T)

'this is a sample sentence whose length i am trying to find'

'THIS IS A SAMPLE SENTENCE WHOSE LENGTH I AM TRYING TO FIND'

String Find and Replace

sentence <- 'I good and I know a good person'
gsub('good','smart',sentence)

'I smart and I know a smart person'