[R] grep problem decimal points looping

[David Winsemius]

On Aug 10, 2010, at 9:17 AM, RCulloch wrote:

>
> Hi R Users,
>
> I have been trying to work out how to rename column names using grep,
> basically I have generated these column names using tapply:
>
>  [1] "NAME"  "X1.1"  "X2.1"  "X3.1"  "X4.1"  "X5.1"  "X6.1"  "X7.1"   
> "X8.1"
> [10] "X1.2"  "X2.2"  "X3.2"  "X4.2"  "X5.2"  "X6.2"  "X7.2"  "X8.2"   
> "X1.3"
> [19] "X2.3"  "X3.3"  "X4.3"  "X5.3"  "X6.3"  "X7.3"  "X8.3"  "X1.5"   
> "X2.5"
> [28] "X3.5"  "X4.5"  "X5.5"  "X6.5"  "X7.5"  "X8.5"  "X1.6"  "X2.6"   
> "X3.6"
> [37] "X4.6"  "X5.6"  "X6.6"  "X7.6"  "X8.6"  "X1.8"  "X2.8"  "X3.8"   
> "X4.8"
> [46] "X5.8"  "X6.8"  "X7.8"  "X8.8"  "X1.9"  "X2.9"  "X3.9"  "X4.9"   
> "X5.9"
> [55] "X6.9"  "X7.9"  "X8.9"  "X1.10" "X2.10" "X3.10" "X4.10" "X5.10"
> "X6.10"
> [64] "X7.10" "X8.10" "X1.12" "X2.12" "X3.12" "X4.12" "X5.12" "X6.12"
> "X7.12"
> [73] "X8.12" "X1.13" "X2.13" "X3.13" "X4.13" "X5.13" "X6.13" "X7.13"
> "X8.13"
> [82] "X1.14" "X2.14" "X3.14" "X4.14" "X5.14" "X6.14" "X7.14" "X8.14"
> "X1.15"
> [91] "X2.15" "X3.15" "X4.15" "X5.15" "X6.15" "X7.15" "X8.15" "X1.16"
> "X2.16"
> [100] "X3.16" "X4.16" "X5.16" "X6.16" "X7.16" "X8.16" "X1.17" "X2.17"
> "X3.17"
> [109] "X4.17" "X5.17" "X6.17" "X7.17" "X8.17" "X1.18" "X2.18" "X3.18"
> "X4.18"
> [118] "X5.18" "X6.18" "X7.18" "X8.18" "X1.19" "X2.19" "X3.19" "X4.19"
> "X5.19"
> [127] "X6.19" "X7.19" "X8.19" "X1.20" "X2.20" "X3.20" "X4.20" "X5.20"
> "X6.20"
> [136] "X7.20" "X8.20" "X1.21" "X2.21" "X3.21" "X4.21" "X5.21" "X6.21"
> "X7.21"
> [145] "X8.21" "X1.22" "X2.22" "X3.22" "X4.22" "X5.22" "X6.22" "X7.22"
> "X8.22"
> [154] "X1.23" "X2.23" "X3.23" "X4.23" "X5.23" "X6.23" "X7.23" "X8.23"
> "X1.24"
> [163] "X2.24" "X3.24" "X4.24" "X5.24" "X6.24" "X7.24" "X8.24" "X1.25"
> "X2.25"
> [172] "X3.25" "X4.25" "X5.25" "X6.25" "X7.25" "X8.25" "X1.26" "X2.26"
> "X3.26"
> [181] "X4.26" "X5.26" "X6.26" "X7.26" "X8.26" "X1.27" "X2.27" "X3.27"
> "X4.27"
> [190] "X5.27" "X6.27" "X7.27" "X8.27" "X1.28" "X2.28" "X3.28" "X4.28"
> "X5.28"
> [199] "X6.28" "X7.28" "X8.28" "X1.29" "X2.29" "X3.29" "X4.29" "X5.29"
> "X6.29"
> [208] "X7.29" "X8.29" "X1.30" "X2.30" "X3.30" "X4.30" "X5.30" "X6.30"
> "X7.30"
> [217] "X8.30" "X1.31" "X2.31" "X3.31" "X4.31" "X5.31" "X6.31" "X7.31"
> "X8.31"
> [226] "X1.32" "X2.32" "X3.32" "X4.32" "X5.32" "X6.32" "X7.32" "X8.32"
> "X1.33"
> [235] "X2.33" "X3.33" "X4.33" "X5.33" "X6.33" "X7.33" "X8.33"
>
> What the names mean are behaviour.day the X is not important to the  
> data, it
> is the numbers I am trying to select on.
>
> So I want to split the data by day i.e. selecting for the number  
> after the
> decimal.
>
> I am using this code (where scananal is the data) with out looping  
> so the
> number following the decimal I change manually (NB the data have been
> changed to character):
>

You need to learn the special character"$" which marks the no- 
character end of string. After creating a replica of your column-names  
with scan and grep:
inp <- scan(what="character")
inX <- inp[grep("X", inp)]

 > DAY <- grep("(X[[:digit:]]+).3$",inX)
 > inX[DAY]
[1] "X1.3" "X2.3" "X3.3" "X4.3" "X5.3" "X6.3" "X7.3" "X8.3"

> DAY <- grep("(X[[:digit:]]+).3",colnames(scananal))
>
> However, this will select for day 3, 30, 31, 32, etc I have tried to  
> use
> fixed = TRUE, but that just returns integer(0). But if I use 30, it  
> will
> select only 30. Not sure what I'm doing wrong here, and I assumed  
> that fixed
> = T would fix this, but doesn't.
>
> I have tried to loop this too, but with no luck, so if anyone can  
> point me
> in the right direction about how to loop using grep I would be most
> grateful!
>
> The main problem I have is where to put the loop, for example:
>
> for(i in 1:33){
> print(i)
> DAY[[i]] <- grep("(X[[:digit:]]+).[[i]]",colnames(scananal))
> }
>
>
> which doesn't work, and no doubt there are obvious reasons for this!  
> Any
> help would be much appreciated,
>
> All the best,
>
> Ross
>
>
>
>
>
>
> -- 
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>
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David Winsemius, MD
West Hartford, CT