On Sep 14, 2008, at 5:39 PM, Adam D. I. Kramer wrote:
Hi Jason,
data[] is a data frame, remember--you need to specify rows AND
columns. So,
data[,c(2,12,17)] is what you should be doing in the first place, and
data[,842:2411] in the second place.
Actually, the construction df[c(2,12,17)] will return just the 2nd,
12th and 17th named column vectors.
Try it and see:
df <- data.frame(a=1:10, b= 10:1, c=LETTERS[1:10])
df
df[c(2,3)]
Not sure if the help you needed was using the comma, or the :
syntax, or if
you're trying to read only certain columns during the read.csv process
(which I don't think that's possible).
? colClasses # with the vector element of NULL for each unwanted
column.
I am not the person to be advising how to do this properly, as all of
my efforts to use this facility to date have failed and I have
resorted to reading in lines with as.is=TRUE and then post-
processing. But the facility does exist.
Maybe someone could give me a clue how one might construct a vector to
send to colClasses inside read.table?
> mt <- matrix(1:200,nrow=4)
> write.table(file=file.choose(), as.data.frame(mt))
> read.table(file.choose())
V1 V2 V3 V4 V5 V6 V7 V8 V9 V10 V11 V12 V13 V14 V15 V16 V17 V18 V19
V20 V21 V22 V23 V24 V25 V26 V27 V28 V29
1 1 5 9 13 17 21 25 29 33 37 41 45 49 53 57 61 65 69 73
77 81 85 89 93 97 101 105 109 113
2 2 6 10 14 18 22 26 30 34 38 42 46 50 54 58 62 66 70 74
78 82 86 90 94 98 102 106 110 114
3 3 7 11 15 19 23 27 31 35 39 43 47 51 55 59 63 67 71 75
79 83 87 91 95 99 103 107 111 115
4 4 8 12 16 20 24 28 32 36 40 44 48 52 56 60 64 68 72 76
80 84 88 92 96 100 104 108 112 116
V30 V31 V32 V33 V34 V35 V36 V37 V38 V39 V40 V41 V42 V43 V44 V45 V46
V47 V48 V49 V50
1 117 121 125 129 133 137 141 145 149 153 157 161 165 169 173 177 181
185 189 193 197
2 118 122 126 130 134 138 142 146 150 154 158 162 166 170 174 178 182
186 190 194 198
3 119 123 127 131 135 139 143 147 151 155 159 163 167 171 175 179 183
187 191 195 199
4 120 124 128 132 136 140 144 148 152 156 160 164 168 172 176 180 184
188 192 196 200
Not working efforts:
tstdta <- read.table(file.choose(), colClasses = c(c(paste(rep("NULL",
49),sep=","),"numeric"),header=TRUE)
tstdta <- read.table(file.choose(), colClasses = paste(rep("NULL",
49),"numeric",sep=","),header=TRUE)
--
David Winsemius
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