R help - Nov 2008 - replacing values in a vector

Hello list.

I have a vector of values:

eg
> head(diff_mirs_list)
[1] "hsa-miR-26b" "hsa-miR-26b" "hsa-miR-23a"
"hsa-miR-27b" "hsa-miR-29a"
[6] "hsa-miR-29b"

and I would like to conditionally replace each value in this vector with a
number defined in a dataframe:
> fc
???????????? Probe ave.fc
1?????? hsa-let-7a?? 1.28
2????? hsa-miR-100?? 1.47
3? hsa-miR-125a-5p?? 1.31
4?? hsa-miR-140-3p?? 1.28
5????? hsa-miR-143?? 1.98
6? hsa-miR-193a-3p?? 1.37
7???? hsa-miR-193b?? 1.48
8????? hsa-miR-195?? 1.16
9????? hsa-miR-214?? 1.22
10???? hsa-miR-23a?? 1.21
11???? hsa-miR-26b?? 1.13
12???? hsa-miR-27b?? 1.37
13???? hsa-miR-29a?? 1.24
14???? hsa-miR-29b?? 1.69
15???? hsa-miR-30b?? 1.16
16???? hsa-miR-424?? 1.42
17? hsa-miR-768-3p?? 1.48
18? hsa-miR-886-3p?? 1.43
19???? hsa-miR-933?? 1.23

ie every hsa-let-7a in the diff_mirs_list is replaced by 1.28, hsa-miR-100 by
1.47 etc etc

I have tried to make a loop to use gsub eg
> for (i in 1:nrow(fc)){
+ test<-gsub(fc[i,1], fc[i,2], diff_mirs_list)
}

but this obviously passes the unchanged vector to gsub each time and so I get
back my 'test' vector with only hsa-miR-933 changed. Could someone help
me out with this please.

Thanks

Iain
> sessionInfo()
R version 2.8.0 (2008-10-20) 
i486-pc-linux-gnu 

locale:
LC_CTYPE=en_GB.UTF-8;LC_NUMERIC=C;LC_TIME=en_GB.UTF-8;LC_COLLATE=en_GB.UTF-8;LC_MONETARY=C;LC_MESSAGES=en_GB.UTF-8;LC_PAPER=en_GB.UTF-8;LC_NAME=C;LC_ADDRESS=C;LC_TELEPHONE=C;LC_MEASUREMENT=en_GB.UTF-8;LC_IDENTIFICATION=C

attached base packages:
[1] stats???? graphics? grDevices utils???? datasets? methods?? base?

Boy are you confused.  This has nothing at all to do with substitution.

Instead do

	test <- with(fc,ave.fc[match(diff_mirs_list,Probe)])

	cheers,

		Rolf Turner

On 7/11/2008, at 11:46 AM, Iain Gallagher wrote:
> Hello list.
>
> I have a vector of values:
>
> eg
>
>> head(diff_mirs_list)
> [1] "hsa-miR-26b" "hsa-miR-26b" "hsa-miR-23a"
"hsa-miR-27b" "hsa-
> miR-29a"
> [6] "hsa-miR-29b"
>
> and I would like to conditionally replace each value in this vector  
> with a number defined in a dataframe:
>
>> fc
>              Probe ave.fc
> 1       hsa-let-7a   1.28
> 2      hsa-miR-100   1.47
> 3  hsa-miR-125a-5p   1.31
> 4   hsa-miR-140-3p   1.28
> 5      hsa-miR-143   1.98
> 6  hsa-miR-193a-3p   1.37
> 7     hsa-miR-193b   1.48
> 8      hsa-miR-195   1.16
> 9      hsa-miR-214   1.22
> 10     hsa-miR-23a   1.21
> 11     hsa-miR-26b   1.13
> 12     hsa-miR-27b   1.37
> 13     hsa-miR-29a   1.24
> 14     hsa-miR-29b   1.69
> 15     hsa-miR-30b   1.16
> 16     hsa-miR-424   1.42
> 17  hsa-miR-768-3p   1.48
> 18  hsa-miR-886-3p   1.43
> 19     hsa-miR-933   1.23
>
> ie every hsa-let-7a in the diff_mirs_list is replaced by 1.28, hsa- 
> miR-100 by 1.47 etc etc
>
> I have tried to make a loop to use gsub eg
>
>> for (i in 1:nrow(fc)){
> + test<-gsub(fc[i,1], fc[i,2], diff_mirs_list)
> }
>
> but this obviously passes the unchanged vector to gsub each time  
> and so I get back my 'test' vector with only hsa-miR-933 changed.  
> Could someone help me out with this please.
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