3. Wk2_DataTypesVectorsAndSubsets2013

# We subset rows and columns of data frames we subset

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Unformatted text preview: n a diﬀerent order •  Elements in a vector – this 6me with names concatenate > c(TRUE, FALSE) [1] TRUE FALSE > c(1.3, 2, 8/3) [1] 1.300000 2.000000 2.666667 > c("a", "z", "Hello") [1] "a" "z" "Hello" > y = c(100, 120) > c(x, y) bob alice john 3 2 1 100 120 •  We can use c() to make logical and character vectors •  No6ce that the last element determines the number of digits to display •  Character vecotr with 3 elements •  c() can be used to catenate vectors 1:3 returns a numeric vector of 1- apart values > 1:3 [1] 1 2 3 > 4:7 [1] 4 5 6 7 > 10:6 [1] 10 9 8 7 6 > 1.1:5.7 [1] 1.1 2.1 3.1 4.1 5.1 > 5.7:1.1 [1] 5.7 4.7 3.7 2.7 1.7 > 5.7:- 1.1 [1] 5.7 4.7 3.7 2.7 1.7 0.7 - 0.3 rep() > rep(3,2) [1] 3 3 > x = c(7,1,3) > rep(x, 2) [1] 7 1 3 7 1 3 > rep(x, 6mes = 2) [1] 7 1 3 7 1 3 > rep(x, c(3, 2, 1)) [1] 7 7 7 1 1 3 > rep(x, each = 2) [1] 7 7 1 1 3 3 •  Vector of two threes •  Arguments of rep can be vectors •  Repeat the vector 2 6mes •  Can use the argument name •  When 6mes argument is a vector then each element is repeated individually •  The Each argument seq() – a richer version of : > seq(1, 5, by = 2) [1] 1 3 5 > seq(1, 5, length = 3) [1] 1 3 5 > seq(1, 5, length = 5) [1] 1 2 3 4 5 > seq(1, length = 5, by = 2) [1] 1 3 5 7 9 > seq(1, 5, length = 5, by = 2) Error in seq.default(1, 5, length = 5, by = 2) : too many arguments •  seq() has several arguments •  from •  to •  by •  length •  There are many ways to call this func6on Ques6on: How could I produce the following vectors (without typing them all out)? 0 0 0 0 0 2 2 2 2 2 4 4 4 4 4 6 6 6 6 6 8 8 8 8 8 rep(seq(0, 8, by = 2), each = 5) 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 rep(1:5, 6mes = 5) 1 2 3 4 5 2 3 4 5 6 3 4 5 6 7 4 5 6 7 8 5 6 7 8 9 rep(1:5, 6mes = 5) + rep(0:4, each = 5) sort() and order() > fage [1] 77 33 79 47 27 33 67 52 59 2...
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## This document was uploaded on 02/16/2014 for the course STATISTICS 3026 at Columbia.

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