Write the output of this code by hand:
f <- function(x) {
m = x
l = x + 4
m = m + 5
return(c(m, l))
}
x = c(1, 2, 3)
f(x)Write the output of this function by hand:
f <- function(x) {
for (i in seq(length(x))) {
x[i] <- x[i] + sum(x) + max(x)
}
return(sort(x))
}
x = c(2, 1, 0)
f(x)Let’s say you fielded a survey and got just 5 responses (…you probably should work on your survey fielding techniques). You collected information about each respondent’s age and gender.
c to create a numeric vector
called age that lists the ages of the five respondents: 19,
34, 7, 18, 67[] to print out the
age of the second person.[] to print out the
age of the second person and third person.c to create a character vector
called gender that lists the gender of the five
respondents: 'male', 'female',
'female', 'male', 'male'adult that indicates whether
each participant was 18 or older. Instead of using c, use a
logical operator like > or >= to
automatically create adult from agegender of all the adult participants.Here are some functions you should be able to write. Any of these may appear (directly or modified) on a quiz or exam! Your function should be able to pass the test functions provided.
reverseVector(x)Write a function that returns the vector in reverse order. So if
x equals c(2,3,4), then
reverseVector(x) should equal c(4,3,2). You
cannot use the rev() function (which does exactly this).
You may not use loops.
dotProduct(a, b)Background: the “dot product” of two vectors is the
sum of the products of the corresponding terms. So the dot product of
the vectors c(1,2,3) and c(4,5,6) is
(1*4) + (2*5) + (3*6), or 4 + 10 + 18 = 32.
With this in mind, write the function dotProduct(a, b).
This function takes two vectors and returns the dot product of those
vectors. If the vectors are not equal length, ignore the extra elements
in the longer vector. You may not use loops.
alternatingSum(a)Write the function alternatingSum(a) that takes a vector
of numbers a and returns the alternating sum, where the
sign alternates from positive to negative or vice versa. For example,
alternatingSum(c(5,3,8,4)) returns 6, because
5 - 3 + 8 - 4 = 6.
median(a)Write the function median(a) that takes a vector of
numbers a and returns the median value in the vector, which
is the value of the middle element (or the average of the two middle
elements).
isNumericLooking(n)Write a function that returns TRUE if the value
n is “numeric looking”, meaning that it is either of a
numeric type or a character type of a number (e.g. “2”). All other data
types and special values (e.g. NA, NaN,
Inf, NULL, TRUE,
FALSE, etc.) should return FALSE.
numericLookingSummary(x)Write the function numericLookingSummary(x) that takes a
vector, x, of either character or numeric values and
returns a vector that contains the minimum value, mean value, maximum
value, sum, and product of the numeric “looking” elements. The function
should convert strings of numbers to actual numbers
(e.g. "2" should be 2). All other data types
and special values (e.g. NA, NaN,
Inf, NULL, TRUE,
FALSE, etc.) should be ignored. The returned vector should
also be named with the following names: min,
mean, max, sum, and
prod. (Hint: you may want to make a helper function first
called isNumericLooking(n) which returns TRUE
if a value is “numeric looking”).
For example,
numericLookingSummary(c(1, "2", 3, 4, NA, 5, NaN, Inf))
should return the following:
## min mean max sum prod
## 1 3 5 15 120Page sources:
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