Ivy Jun 01, 2018 No Comments
Have an interview tomorrow? Facing last moment preparation issues? Well, we bring to you this Base R Cheat Sheet to ace up your chances of getting employed.
As Data Exploration and Data Manipulation takes most of the time, chances of being questioned as to how shall you deal with an unstructured data and manipulate them are high.
Getting Started with Libraries
install.packages(“dplyr”)
Allows download and install packages from the CRAN repository.
library(dplyr) :
Loads the package in the session in order to allow the use of the functions.
Working Directory
getwd()
To get the current location of the directory.
setwd(“file path”)
To change the current working directory.
Reading and Writing Data
data <- read.csv(“file.csv”)
To read or import data as a CSV file.
write.csv(data, “file.csv”)
To write or export data.
Converting Data Types
as.logical
To convert into the Boolean form
as.numeric
To convert to numeric
as.factor
To convert into factors
Mathematical Functions
log(x)
To calculate natural log.
exp(x)
To calculate exponential
round(x,n)
To round a number to n decimal places
corr(x,y)
To find a correlation between 2 variables
Dealing with Data Frames
df <- data.frame(x = 6:10, y = c( ‘ a’, ‘b’, ‘c’)
Creating a data frame
df$x
Accessing a column of a data frame
view(df)
To look at the whole data set
dim(df)
number of rows and columns in a data frame
rbind
binding rows
cbind
binding columns
Dealing with strings
paste(x, y, sep =’ ‘)
To join multiple vectors together
grep(pattern, x)
To find regular expression matches in x
gsub(pattern, replace, x)
To replace matches in x with a string
toupper(x)
To convert a string to upper case
nchar(x)
To find the number of characters in the string
Plotting data
plot(x, y)
Bivariate plot
hist(x)
Plotting a histogram
barplot(x)
Plotting bar plots
pie(x)
Plotting a piechart
stripplot(x)
Plotting values of x on a line (an alternative to boxplot for small values)
Statistics
lm(formula, data=)
Fitting a linear regression model
glm(formula, data=, family=)
Fitting a generalized linear model
predict(fit)
To predict on the fitted model
fitted(fit)
To obtain fitted values
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