[Tutor] The concept of string arrays

[Erik Price]

On Monday, February 3, 2003, at 07:30  PM, andy surany wrote:

> I'm reading an Excel file into memory. The values are all strings. My 
> no
> frills approach to doing this was to simply set up a list, read the
> values from a file, and append the list. Each element is then 
> referenced
> via position. For example,
>
> First_Name    Last_Name    Address    Date_of_Birth
>
> would be input as follows:
>
> client.append(First_Name)
> client.append(Last_Name)
> client.append(Address)
> client.append(Fate_of_Birth)
>
> now if I want to reference the 45th row in the cell, I would start at
> position 45*4.
>
> This works - but I know that there have to be more elegant solutions. I
> tried creating a 4 dim array - but found that string types were not
> allowed. Is it possible to create a multi dimensional list or tuple?
> or????

Elegance is probably in the eye of the beholder, but I personally hate 
multi-dimensional arrays.  Maybe they're helpful if you're programming 
in C, or if you're concerned with performance, I have no idea.  Why not 
just create a couple of objects to represent the data you're working 
with?

My own approach would be to create a Record or Row class that 
represents a row of the spreadsheet.  It would have four fields, each 
named after one of the columns.  You could write another object called 
SpreadSheet which could serve as a handy wrapper object around a list 
(or perhaps a tuple if you're doing read-only work), with some 
convenience methods.

The Record object is probably self-explanatory, but the SpreadSheet 
class might look something like:

class SpreadSheet:
   def __init__():
     this.recordlist = []

   def get_records:
     return this.recordlist

   def get_record(index):
     return this.recordlist[index]

   def append_record(record):
     this.recordlist.append(record)

   def read_record():


...etc...

Then, when you want to use your classes, you can do something to the 
effect of:

f = open("spreadsheet.xls")
ss = new SpreadSheet()
for i in f.readlines():
   r = new Record(i)
   ss.append(r)

or something like that.  (I haven't written Python in a long time so my 
syntax may be incorrect, but it's to give you the gist of what one 
person considers elegant.)

As I said before, it's a matter of taste, but I find that designs which 
make use of objects help clarify what is going on in the program and 
make for a more elegant design.


Erik






-- 
Erik Price

email: erikprice@mac.com
jabber: erikprice@jabber.org