Manav Goyal

R - Others

Topic

  • Basic
    • # => Comment
    • max(varV) => Returns maximum value
    • min(varV) => Returns minimum value
    • log(10) => Computes common logarithms
    • log(n, base=n)
    • var = n + im => Complex value
    • Re(var)
    • Im(var)
    • Conj(var) => Complex conjugate
    • Mod(var) => Complex Modulus
    • Arg(var) => Complex Argument
    • solve(n,m) => Solves nx=m and returns value of x
    • mode(varV) => Type of storage
    • mean(varV) => Calculates Mean
    • median(varV) => Calculates Median
    • var(varV) => Calculates Variance
    • summary(varV) => Gives various information about the vector
    • cumsum(varV) => Calculates cumulative sum
  • Data Types
    • var <- value => Value is assigned to Variable
    • value -> var
    • var <- NA => Missing Observations
    • is.na(var) => Returns true if missing data, If value is set to NA
    • var = value
  • Vector
    • varV = c(1,2,3,4,5) => Combines the numbers 1,2,3,4 and 5 to a vector
    • varV[n] => Returns nth element, Index starts from 1
    • varV[c(n1,n2,n3)] => Returns n1, n2, n3 element
    • varV[-n] => Returns all but the nth element
    • varV[n1:n2] => Returns elements from n1 to n2 index
    • sort(varV) => Sorts the values of vector in ascending order by default
    • sort(varV, decreasing=TRUE) => Sorts the values of vector in descending order
    • length(varV) => Gets or sets the length of a vector (list) or other objects
    • varV[varV > n] => Returns elements greater than n
    • varV[(varV%%2)==0] => Returns only even elements
    • varV[varv %in% n1:n2] => Returns elements with values from n1 to n2
  • Set Operations
    • union(varV1, varV2) => Returns union of both vectors
    • c(varV1, varV2) => Returns concatenation of both vectors
    • intersect(varV1, varV2) => Returns intersection of both vectors
    • setdiff(varV1, varV2) => Returns difference of both vectors
  • Matrix
    • varM <- matrix(nrow=n, ncol=m, data=c(n1, n2, n3, n4)) => Create a matrix, Data entered column-wise
    • var[n,m] => Access the element in this position
    • var <- matrix(nrow=n, ncol=m, data=c(n1, n2, n3, n4), byrow=TRUE) => Create a matrix, Data entered row-wise
    • dim(var) => Dimension of matrix
    • nrow(var) => Number of rows
    • ncol(var) => Number of column
    • attributes(var) => Informs the dimension of matrix
    • var <- matrix(nrow=n, ncol=m, data=n) => Create a matrix, Data entered to all is n
    • var <- diag(1, nrow=n, ncol=n) => Create a identity matrix of size n
    • var2 <- -t (var1) => Transpose of a Matrix
    • var*n => Multiplication of a matrix with constant n
    • var3 <- var1 %*% var2 => Matrix Multiplication
    • var2 <- crossprod(var1) => Cross Product of matrix with a Function
    • var1 + var2 => Addition of matrix of same Dimension
    • var[n, ] => Access the nth row
    • var[ ,m] => Access the mth column
    • var[n1:n2, m1:m2] => Access m1 to m2 column of n1 to n2 row
    • solve(var) => Finds the inverse of a positive definite matrix
    • eigen(var) => Finds the eigen values and eigen vectors of a positive definite matrix
    • var <- matrix(1:6, n, m, byrow=T) => Create a matrix with values 1 to 6
    • var <- rbind(var, n1:n2) => Adds a row with n1 to n2 values
    • var <- cbind(var, m1:m2) => Adds a column with m1 to m2 values
    • var[n, ] <- n1:n2 => Change entire nth row from n1 to n2
    • var[ ,m] <- m1:m2 => Change entire mth column from m1 to m2
    • var <- var[-n, ] => Delete nth row
    • var <- var[ ,m] => Delete mth column
  • Sequence
    • seq(from=n, to=m) => Generate a sequence from n to m
    • seq(n, m) => Generate a sequence from n to m
    • seq(from=n, to=m, by=o) => Generate a sequence from n to m with a gap of o
    • seq(n, m, by=o) => Generate a sequence from n to m with a gap of o
    • seq(from=n, length=m) => Generate a sequence from n up to length m
    • seq(n, m, o) => Generate a sequence from n to m with a gap of o
    • seq(as.Date("2021-11-11"), by=years) => Generating sequence of Dates
    • letters => Generates sequence of all letters from a to z
    • letters[n1:n2] => Generates letters from n1 to n2
    • letters[n2:n1] => Generates letters in reverse order from n2 to n1
    • LETTERS => Generates sequence of all uppercase letters from a to z
  • Repeat
    • rep(n, times=m) => Repeats n m times
    • rep(n1:n2, times=m) => Repeats n1 to n2 m times
    • rep(n1:n2, each=o) => Repeats n1 m times, n2 m times and so on
    • rep(n1:n2, each=o, times=m) => Repeats n1 m times, n2 m times and so on, m times
    • rep(n1:n2, m1:m2) => Repeats n1 m1 times, n2 m2 times and so on
    • rep(n1:n2, seq(from=n, to=m, by=o)) => Repeats n1 n times, n2 n+o times and so on
    • rep(varM, m) => Repeats a matrix m times
    • rep(c("a","b","c"), m) => Repeats the given characters m times, It can also be string in place of character
  • Conditional
    • ifelse(test, yes, no) => If test is TRUE then perform yes operation else no operation
    • for(i in n1:n2) {statement}
    • for(I in varV) {statement}
    • while(condition) {statement}
    • which(condition) => Selects which satisfies the condition
    • repeat {statement} => Does not check any condition
  • Data Frame
    • library(MASS)
    • painters => Provides random data to work on
    • rownames(painters)
    • colnames(painters)
    • str(painters) => Returns structure of the Data
    • painters$var => Extract a variable from the data frame
    • subset(painters, painters$var=="value") => Get subset of a data frame
    • split(painters, painters$var) => Partitions the data set by values of a specific variable
    • painters$var = factor(painters$var, labels = c("value1", "value2")) => Sets values of variable in painters equal to given values based on its 1 & 0
    • table(painters$var) => Creates a one way table for this variable
    • table(painters$var1, painters$var2) => Creates a two way table for this variable
    • var <- data.frame(x, y, z) => Creates random data based on this
  • Graph
    • plot(var, type="1")
    • plot(var, xlab="value1", ylab="value2") => Gives names to the x and y axis
    • plot(var, col="value")
    • plot(var, main="value") => Gives Title to the graph
    • pie(var) => Generates a Pie chart
    • barplot(var, beside=T) => Generates a Bar plot
      • legend=rownames(table5)
      • xlim=c(1,15),ylim=c(0,5)
      • col=c("blue","red")
    • boxplot(var1 ~ var2)
      • col=c("red","blue")
  • Sort
  • Repeat
  • Operators
  • Tables

Others

  • Theory
    • Install R
      • Go to r-project.org > Click Download R > Click on link on O-cloud > Click on for Windows > Click Version
    • Download R Studio
      • Go to rstudio.com > Click Download R Studio > Click Desktop > Click on Free version > Select operating System
    • Package
      • Base => Installed with R but not loaded by Default
      • Contributed => Need to be Downloaded, Installed & Loaded separately
  • Shortcuts
    • ctrl + Enter => Run Program
    • ctrl + R => To execute highlighted line
  • Console Commands
    • license()
    • demo()
    • help()
    • help.start()
    • q() => Quit R
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