Unformatted text preview: d to bexer understand: • How to use logical operators to create logical vectors • How to create vectors with speciﬁc numbers and/or lexers Review: subse4ng vectors Subset by posi6on age
position
1
3
7
8 73
33
79
47
27
33
67
52
59
27
55
24
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48 subset
73
79
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52 Subset by posi6on age
position
1
8
7
3 73
33
79
47
27
33
67
52
59
27
55
24
46
48 subset
73
52
67
79 Subset by exclusion age
exclusion
2
4
5
6
9
10
11
12
13
14 73
33
79
47
27
33
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59
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24
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48 subset
73
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52 Subset by logical logical
T
F
T
F
F
F
T
T
F
F
F
F
F
F age
73
33
79
47
27
33
67
52
59
27
55
24
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48 subset
73
79
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52 Subset by name name "a"
"c"
"g"
"h" name
"a"
"b"
"c"
"d"
"e"
"f"
"g"
"h"
"i"
"j"
"k"
"l"
"m"
"n" age
73
33
79
47
27
33
67
52
59
27
55
24
46
48 subset
73
79
67
52 Five ways to subset a vector • Posi6on – indices of the element you want • Exclusion – indices of elements to exclude • Logical – logical vector the same length as the vector being subset. Keep the elements corresponding to TRUE. • Name – character vector of names of elements to keep. Vector being subsexed must have names associated with elements • All – all the elements Logical Opera6ons Logical/Rela6onal Operators • In addi6on to operators such as +,  , *, and / R also has logical operators • They are rela6onal operators >, <, >=, <=, !=, and ==!
• These return a value of TRUE or FALSE • They are also vectorized opera6ons Examples > 4 < 3!
[1] FALSE!
> "a" == "A"!
[1] FALSE!
> "A" == "A"!
[1] TRUE!
> 4 != 3!
[1] TRUE! > fweight > 150!
[1] TRUE FALSE TRUE TRUE FALSE TRUE
[9] TRUE TRUE TRUE FALSE FALSE FALSE! TRUE FALSE > fgender !="m"!
[1] FALSE TRUE FALSE FALSE TRUE TRUE FALSE
[9] FALSE FALSE TRUE FALSE FALSE TRUE! TRUE > fbmi!
[1] 25.16239 21.50106 24.45884 24.48414 18.06089
[6] 28.94981 28.18797 20.67783 26.66430 30.04911 !
[11] 26.05364 22.64384 24.26126 22.91060! > fbmi == 25.16239!
[1] FALSE FALSE FALSE FALSE FALSE FALSE …! ! Weights of the women in our family • Create a logical expression that iden6ﬁes the women in the family > fgender == "f"!
[1] FALSE TRUE FALSE FALSE TRUE TRUE FALSE
[8] TRUE FALSE FALSE TRUE FALSE FALSE TRUE! • Use this logical expression to subset the vector of fweight > fweight[ fgender == "f"]!
[1] 125 105 190 124 166 125! ! Boolean Algebra • Boolean algebra is a mathema6cal formaliza6on of...
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 Fall '14
 Prime number

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