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

[Santosh Srinivas]

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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