st: How blanks are treated when vars are read in as string from anASCII raw data file

[Clare L Maxwell <maxwellcl1@earthlink.net>]

Hello again to the Statlist writers.

This is a reprise of a problem I asked about yesterday, involving a 
6-place string subject identifier that is read in from an ASCII file. 
In the ASCII file, this is how the data look:

B    1
B  120
CCH  7
CCH 23
CCH213
UW  23
UW 232

I want to turn them into a variable that looks like this:

  B001
  B120
CCH007
CCH023
CCH213
 UW023
 UW232

I had two very helpful recommendations on how to accomplish this. 
However, the results were not as hoped.

I read the data into Stata as two str3 variables:

infile dictionary using "/Projects/Christina/HNS/Stata/data/cm1.raw" {
  str3       site         %3s
  str3       siteid       %3s
...... many more vars
  }

I was surprised when they looked like this in Stata:

site siteid
   B      1
   B    120
 CCH      7
 CCH     23
 CCH    213
  UW     23
  UW    232

In other words, now they both appeared as right justified once they 
had been read in (siteid was that way before in the ASCII file).

This saved me the trouble of manipulating site.  However, when I 
tried to left pad siteid with zeros, as suggested by Ian Watson and 
Nick Cox:

replace siteid = subinstr(siteid," ","0",.)

I got the message that zero replacements have been made.  When I 
concatenated the site and siteid to get my final ID variable, I got 
the following:

    B1
  B120
  CCH7
 CCH23
CCH213
  UW23
 UW232

This is similar to problems I was having before my original letter. 
There must be something I do not understand how blanks are treated in 
string variables created this way.  In the ASCII file, these 
variables are not enclosed in quotation marks to signify that they 
are string variables.  I just say string and how long when they are 
read in.  I later merge three files by these IDs plus dates, and in 
order to do that, I have to compress the files.  I thought 
compression might have been the problem.  Sadly, not compressing did 
not resolve this.  I also just updated Stata.  No change.  Can anyone 
shed more light?

Thank you very much for your help.

				Yours truly,
				Clare Maxwell
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