[datatable-help] Append missing characters to character variable to bring to a standard length

[Bacou, Melanie]

substr() needs argument fixed=TRUE or else it uses regex expression for 
string matching and replacements.
I'd suggest you look into stringr::str_pad(x, 6) or formatC(x, width = 
6, format = "d", flag = "0") for faster ways to achieve this.
--Mel.


On 1/5/2015 11:44 PM, Santosh Srinivas wrote:
> Hello All,
>
> I am trying to create a character variable in my data table so that it 
> is *atleast* 6 characters long.
> The last line seems to be going wrong.
>
> Please advise. Reproducible code below
>
> require("data.table")
> value <- sample(seq(60:1000),100) #Random data
> dt <- as.data.table(value)
> dt[,value:=as.character(value)] #Cast as character
> dt[, value_MISSINGDIGITS:=6-nchar(value)] #Check for # of characters 
> missing
> dt[, value_MISSINGDIGITS:=value_MISSINGDIGITS*(value_MISSINGDIGITS>0)] 
> #Handle negative values
>
> # This works till here!
> # The missing character count works correctly above
>
> # The below fails. I am trying to generate dummy 0s to fill the 
> missing characters. The values do not get generated accurately
> dt[,value_MISSINGPART:=substr("000000",0,value_MISSINGDIGITS)]
>
>
> > sessionInfo()
> R version 3.1.2 (2014-10-31)
> Platform: x86_64-apple-darwin13.4.0 (64-bit)
>
> locale:
> [1] C
>
> attached base packages:
> [1] stats     graphics  grDevices utils     datasets  methods   base
>
> other attached packages:
>  [1] fractalrock_1.1.0   quantmod_0.4-0      TTR_0.22-0       
>  xts_0.9-7           zoo_1.7-11  Defaults_1.1-1
>  [7] futile.logger_1.3.7 futile.any_1.3.0  lambda.r_1.1.6     
>  timeDate_3011.99    lubridate_1.3.3 data.table_1.9.4
>
> loaded via a namespace (and not attached):
>  [1] Rcpp_0.11.3          chron_2.3-45 digest_0.6.4         
> futile.options_1.0.0 grid_3.1.2
>  [6] lattice_0.20-29      memoise_0.2.1        plyr_1.8.1           
> reshape2_1.4         stringr_0.6.2
> [11] tools_3.1.2
>
>
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-- 
Melanie BACOU
International Food Policy Research Institute
Snr. Program Manager, HarvestChoice
Work +1(202)862-5699
E-mail m.bacou at cgiar.org
Visit www.harvestchoice.org

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