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Statistical Analysis: an Introduction using R/R/Vectors
1
Statistical Analysis: an Introduction using
R/R/Vectors
One of the most fundamental objects in R is the
vector
, used to store multiple measurements of the same type (e.g.
data variables). There are several different sorts of data that can be stored in a vector. Most common is the
numeric
vector
, in which each element of the vector is simply a number. Other commonly used types of vector are
character
vectors
(where each element is a piece of text) and
logical vectors
(where each element is either TRUE or FALSE
[1]
). In this topic we will use some example vectors provided by the "datasets" package, containing data on States of the
USA (see ?state).
R is an inherently vectorbased program; in fact the numbers we have been using in previous calculations are just
treated as vectors with a single element. This means that most basic functions in R will behave sensibly when given a
vector as a argument, as shown below.
Input:
state.area
#a NUMERIC vector giving the area of US states, in square miles
state.name
#a CHARACTER vector (note the quote marks) of state names
sq.km < state.area*2.59
#Arithmetic works on numeric vectors, e.g. convert sq miles to sq km
sq.km
#... the new vector has the calculation applied to each element in turn
sqrt(sq.km)
#Many mathematical functions also apply to each element in turn
range(state.area)
length(state.area)
#and some, like this useful one, just return a single value.
Result:
> state.area
#a NUMERIC vector giving the area of US states, in square miles
[1]
51609 589757 113909
53104 158693 104247
5009
2057
58560
58876
6450
83557
56400
[14]
36291
56290
82264
40395
48523
33215
10577
8257
58216
84068
47716
69686 147138
[27]
77227 110540
9304
7836 121666
49576
52586
70665
41222
69919
96981
45333
1214
[40]
31055
77047
42244 267339
84916
9609
40815
68192
24181
56154
97914
> state.name
#a CHARACTER vector (note the quote marks) of state names
[1] "Alabama"
"Alaska"
"Arizona"
"Arkansas"
[5] "California"
"Colorado"
"Connecticut"
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This note was uploaded on 10/18/2011 for the course POL POL 51 taught by Professor Haptosthal during the Fall '11 term at UC Davis.
 Fall '11
 Haptosthal

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