[Tutor] Pass arguments from bash script to embedded python script

[David L Neil]

On 24/10/19 8:08 AM, Stephen P. Molnar wrote:


 > I have revised my script to make use of the def function:

Back in FORTRAN we used to write:

	FUNCTION FUNCNAME( args )
	- specific code to implement some purpose

This, in Python, is similar. Try 'translating' "def" as "define 
function", to clarify: 'I am defining function dG'...


Please copy-paste the exact code in-use and errmsg-received, because 
what came-through doesn't make sense - likely re-formatted by the email 
system.


This is a problem:

 > fname = fileList
 > for fname in fname:
 >      fname

- fname is first set to a list
- then it is used as an iterator (right side)
	AND as a (single) variable
- finally it is used for something?what?

Apparently the same varNM is being used and re-used, for quite different 
purposes!

Whereas fileList gives a clear impression that it is a collection of 
items, "fname" suggests that it holds a single file's name.

That said, why not?

	for fname in fileList:
		# do something with fname

NB what followed the above (in the email listing) should likely be 
indented (per criticism, above)


Also:

 > where fileList = ['C-VX3', '15-7', '14-7']

This is 'for our information' and not actually part of the code-snippet 
- is it?


Is the dG function designed to accept a single file-name at a time, eg 
'C-VX3' or all three at once?

 > data = dG(filesList)

is declaring all three/the entire list as parameters!


The current design (it seems to me, reading-around any email 
re-formatting issue)
1 (loop nr1) scan the currentDIR for .log files
2 add each .log file to a list [you advise that there are three]
3 (loop nr2) pick each fileNM in the (above) list, and
4 dG() it

If you combine the two loops, many (apparent) problems should 'disappear':

1 scan the currentDIR for .log files (existing)
2 manipulate the fileNM (existing)
3 dG() it (existing)


Which brings me back to "naming":

 > for files in glob.glob("*.log"):

<<<
  glob.glob(pathname, *, recursive=False)

     Return a possibly-empty list of path names that match pathname...
 >>>

- is "files" a (single) file's *name* or a list of file-names?
(the glob.glob part is indeed a list, but files is (a) singular and (b) 
a file-name (actually, a "path-name").)

Apologies, if seeming pedantic, but an incorrect choice of varNM may 
introduce a confusion which prevents comprehension/debugging.


Good idea to use some 'debug prints'! Even better, that if you are using 
r3.8 you can take advantage of a brand-new feature:

 > print('fname = ', fname)

print( f"fname =" )

NB the "f" preceding the quoted-string is deliberate and important - we 
call these "f-strings".

My ToDo list includes (continuing to research/check first, then) 
upgrading to r3.8 - even as 'f-string debug printing' is the nr1 
personal appeal to this lazy-boy!


To help with learning Python, are you aware that Python allows, even 
enables, you to experiment and thus develop a program, line-by-line?

- open a terminal window and start python3
- try these two lines (abstracted from the code):

import glob
glob.glob("*.log")

NB the second statement is an implicit version of:

	print( glob.glob("*.log") )

- you should see something like (your):

	['C-VX3', '15-7', '14-7']

Now, you have an exact illustration and on-screen evidence of what is 
happening!

You can continue adding (your) lines of code, one-at-a-time. (in which 
case, at least initially, avoid loops and aim to get (only) 'the first 
one' to work). Once you have learned the necessary Python syntax and 
bent the code to your will, the pertinent/working parts can be copied 
into a editor and saved as a file. Then you can install loops (and 
indents!) and all the bells-and-whistles your little heart desires...

Sage advice passed to a (much) younger me: "Make it work, before you 
make it better". Python's "REPR" makes enacting such advice SO much easier!


Also, which editor are you using?


WebRef: https://docs.python.org/3.7/library/glob.html
-- 
Regards =dn