MGSC 291 Exam 1 Questions and Answers Graded A+

MGSC 291 Exam 1 Questions and
Answers Graded A+

addition - Correct answer-R code: +

subtraction - Correct answer-R code: -

multiplication - Correct answer-R code: *

division - Correct answer-R code: /

exponent - Correct answer-R code: ^

note (anything after this symbol will be ignored by R) - Correct answer-R code: #

defines an object - Correct answer-R code: <-

combine function (creates a vector of numbers. numbers can either be separated by

commas, or by a colon (1,2,3,4) or 1:4) - Correct answer-R code: c

sequence function (creates a vector with the sequence (from, to, by) ex:

seq(1,10,0.1) creates a vector from one to 10 counting by 0.1) - Correct answer-R

code: seq()




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,help function (opens a web browser to display a help file) - Correct answer-R code:

help(functionName)

missing value - Correct answer-R code: NA

average - Correct answer-R code: mean ()

removes all missing values (from the given data set. in R all missing values are

labeled as NA) - Correct answer-R code: na.rm=T

square root - Correct answer-R code: sqrt()

natural logarithm - Correct answer-R code: log()

e^a - Correct answer-R code: exp(a)

sample standard deviation - Correct answer-R code: sd()

sample variance - Correct answer-R code: var()

length of vector (including NAs) - Correct answer-R code: length()

dimension of data frame - rows, columns - Correct answer-R code: dim()

makes R recognize x as categorical - Correct answer-R code: factor(x)

bind (combine) objects by columns - Correct answer-R code: cbind()

bind objects by rows - Correct answer-R code: rbind()



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, sort from smallest to largest - Correct answer-R code: sort()

sort a data frame based on specified columns(s) - Correct answer-R code: order()

round x to a decimal places - Correct answer-R code: round(x,a)

repeat x n times - Correct answer-R code: rep(x,n)

returns the position number where argument is true - Correct answer-R code:

which()

if condition is met, return a, otherwise return b - Correct answer-R code:

ifelse(cond,a,b)

sample from a dataset - Correct answer-R code: sample()

concatenate text - Correct answer-R code: paste()

returns a list of all stored objects - Correct answer-R code: object() or ls()

equal to - Correct answer-R code: ==

not equal to - Correct answer-R code: !=

less than - Correct answer-R code: <

less than or equal to - Correct answer-R code: <=

greater than - Correct answer-R code: >



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