[Tutor] Suggestions to improve this first effort?

[bob gailer]

C B Gambrell wrote:
> I am just getting started with Python and wonder if folks here might
> look at this attempt in Python and offer me your thoughts.
>
> Several years ago I used QBasic to convert one our reports to a csv
> file so we could import the data into another program.  That very old
> QBasic script has been serving me well but I decided to try to make it
> work in Python.  I used the same logic in Python I had used in QBasic
> and the resulting output is exactly what I need.
>
> Here is how the data looks in the input file.
>
> =====
> =====
> .block
>   name 1
>   address1
>   city st
>   11111
> .endblock
> .report
>
>
> .block
>   name 2
>   address 2
>   city st
>   11111
> .endblock
> .report
> ====
> ====
>
> The input file goes on for several thousand addresses.
>
> Here is what worked for me in QBasic.
>
> ===
> ===
> clin1$ = ""
> clin2$ = ""
> infile$ = "ad.txt"
> outfile$ = "ad.csv"
> '
> OPEN infile$ FOR INPUT AS #1
> OPEN outfile$ FOR OUTPUT AS #2
> '
> DO WHILE NOT EOF(1)
>         LINE INPUT #1, lin$
>         clin1$ = RTRIM$(LTRIM$(lin$))
>         IF clin1$ = "" THEN
>                 clin1$ = ""
>         ELSEIF clin1$ = ".report" THEN
>                 clin1$ = ""
>         ELSEIF clin1$ = ".block" THEN
>                 clin1$ = ""
>         ELSEIF clin1$ = ".endblock" THEN
>                 WRITE #2, MID$(clin2$, 4)
>                 PRINT MID$(clin2$, 4)
>                 clin2$ = ""
>         ELSE
>                 clin2$ = clin2$ + CHR$(34) + CHR$(44) + CHR$(34) + clin1$
>         END IF
> LOOP
> END
> ====
> ====
>
> And here is my I got work for me in Python.
>
> ===
> ===
> import sys
> infile=sys.argv[1]
> outfile=sys.argv[1]+".csv"
>
> f1=open(infile)
> f2=open(outfile, 'w')
>
> s2=""
>
> for line in f1:
> 	s=line.strip()
> 	if s=="":
> 		continue
> 	elif s==".block":
> 		continue
> 	elif s==".report":
> 		continue
> 	elif s==".endblock":
> 		s="\n"
> 		s2=s2[:-1]+s
> 		f2.write(s2)
> 		s2=""
> 		continue
> 	s2=s2+"\""+s+"\""+","	
>
> f1.close()
> f2.close()
> ===
> ===
>
> The script works but what you suggest to improve the logic or make the
> script more Pythonic?
>   
Dunno if this is more Pythonic, but it's how I'd code it:

...
f2 = open(outfile, 'w')
for line in f1:
	if s.startswith(".block"): # start of block
		s2 = []
	elif s==".endblock":
		f2.write(",".join(s2) + "\n")
	else: # data record
		s2.append('"%s"' % line.strip())
...


-- 
Bob Gailer
919-636-4239 Chapel Hill, NC