Dailycoding-Challenge/Day52.Rhtml at master · rladiestunis/Dailycoding-Challenge · GitHub

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<html>

<head>
<title>Day 50 #dailycoding challenge ⬇️</title>
</head>

<body>

Day 52 of #dailycoding challenge ⬇️

Today we will talk about #Vectors and #matrixes in #R .

A #Vector is a basic data structure that contains element of similar type (logical, integer, double, character, complex or raw).

A #Matrix is basically a two-way generalization of a #Vector. Instead of a single index, we can use two indexes, one representing a row and the second representing a column.

Maths Functions are applicable on this data structures.

Code on #github 👉 https://github.com/rladiestunis/Dailycoding-Challenge

Happy Coding Learning !


<!--begin.rcode
# $$$$$$$$$-Vectors-$$$$$$$$$ :
##**** Creating vectors : (in 5 ways)
###---1---: join elements into a vector
c(2,4,6)
###---2---: an integer sequence
2:6
###---3---: a complexe sequence
seq(2,3 , by=0.5)
###---4---: repeat a vector
rep(1:2 , times=3)
###---5---: repeat elements of a vector
rep(1:2 , each=3)

##**** vector functions :
x = c(2,-5,8,4,10,7,-6,1,1)
### print length :
length(x)
### return x soted
sort(x)
### return x reversed :
rev(x)
### see counts of values :
table(x)
### see unique values
unique(x)

##**** selecting vector elements :
### by position :
#### the fourth element :
x[4]
#### all but the fourth :
x[-4]
#### elements two to foor : (slicing)
x[2:4]
#### all elements except two to four :
x[-(2:4)]
#### elements one and five :
x[c(1,5)]
### by position :
#### elements wich are equale to 10 :
x[x==10]
#### All elements less then 0 :
x[x<0]
#### elements in the set 1,2,5 :
x[x %in% c(1,2,5)]
### named vectors :
x['apple']
end.rcode-->

<p>You can also embed plots, for example:</p>

<!--begin.rcode fig.width=7, fig.height=6
# $$$$$$$$$-Matrixes-$$$$$$$$$ :
##**** Creating matrixes :
m = matrix(x , nrow=3 , ncol=3)

##**** matrix functions :
### print dimension (number of columns and rows):
dim(m)
### print number of rows :
nrow(m)
### print number of columns :
ncol(m)
### print n row (in this cse we will try n=2) :
head(m,2)
### bind columns :
cbind(m)
### bind rows :
rbind(m)
### transpose :
t(m)
### matrix multiplication :
m %*% n
### find x in: m*x=n :
solve(m,n)

##**** selecting matrix elements :
### select a row (second row in this case):
m[2, ]
### select a column (first column in this case) :
m[,1]
### select an element(elemnt in the intersection betwin the second row and the third column) :
m[2,3]
end.rcode-->

</body>
</html>