[Tutor] CSV Module

[Mishu]

   Was hoping to get some help with this below:

   [1]https://stackoverflow.com/questions/60398386/how-to-scrape-google-maps-for-all-data-using-python

    

   e.g. if you want to get All the starbucks locations / addresses from
   google maps ?

    

   thanks so much

    

   Sent from [2]Mail for Windows 10

    

   From: [3]Mats Wichmann
   Sent: Sunday, September 27, 2020 11:13 AM
   To: [4]tutor at python.org
   Subject: Re: [Tutor] CSV Module

    

   On 9/25/20 11:18 PM, Manprit Singh wrote:

   > Dear Sir,

   >

   > Consider a tuple (more precisely a nested tuple)as given below :

   > tup = (("1", "Andy", "Science",),

   >            ("2", "Robin", "Arts",), )

   >

   > First of all i just need to know , if i maintain a habit to include a
   comma

   > even after the last element of tuple and list . As you can see I have

   > placed a comma just after "Science"  and "Arts"  as well as after the
   two

   > tuples ("1", "Andy", "Science",) and

   > ("2", "Robin", "Arts",) . Is it a good habit ? I read somewhere that it
   is

   > better to write lists and tuples in this way . Need your comments.

    

   One reason people suggest the trailing comma is it shows less change in

   a diff if you later add elements. That consideration only matters on

   multi-line definitions.  That is, if you add an element to your internal

   tuple so:

    

   ("1", "Andy", "Science",),

    

   becomes

    

   ("1", "Andy", "Science", "Freshman".),

    

   well - the line changed anyway, so you didn't save anything by the

   trailing comma...

    

   but if you add lines, and lay it out like this:

    

   tup = (("1", "Andy", "Science",),

              ("2", "Robin", "Arts",),

   )

    

   Now adding a new entry is just adding a line, and the diff won't also

   show the "2" tuple as having changed, because you needed to add a

   trailing comma to it becasuse it's no longer the last element.

    

   Does that make sense?

    

   > Another  Question is now if i have to read the same csv, What about the

   > below written code. Need your humble comments

   >

   > with open('some.csv', newline='') as f:

   >     reader = csv.reader(f)                      # Reader object

   >     for row in reader:

   >         print(row)                                     # Prints each row

   >

   > Coming to the main point now :

   > The code written just above closes the file at the point when  all rows
   are

   > printed, and once the file is closed you can not again access the same
   file

   > without repeating the same process . Now if i have to access this csv
   file

   > lots of time in a single program , Repeating the same above written
   process

   > again and again is the only way ?  Can i assign this CSV file to a
   variable

   > so that i can use this csv file number of times in a programme ?Need
   your

   > humble comments in this regard

    

   The use of a context manager (with statement) is nice because it handles

   cleanup for you after the context is complete, something which it turns

   out is easy to forget.  If your context for manipulating the file is

   bigger than that, and not cleanly contained in one smallish code block,

   then don't use a context manager - just remember to clean up after
   yourself.

    

   Yes, of course you can assign the open file object to a name and

   continue to use it.

    

   f = open('some.csv, newline='')

    

   But... once you've read all the data from the file the way you're

   showing, you're "off the end" and any future reads will return empty.

   So if you want to continue using you're going to need to reset the file

   pointer .. for example the seek method.  You'll perhaps also want to

   think about what mode you open the file in (if you don't supply the

   mode, it defaults to 'r' - read only).

    

   I think there are people who feel if you've got access to a file

   scattered all around your code instead of in a neat self-contained block

   suitable for a context manager, you may need to consider if your code is

   optimally organized... just something else to think about.

    

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References

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   1. https://stackoverflow.com/questions/60398386/how-to-scrape-google-maps-for-all-data-using-python
   2. https://go.microsoft.com/fwlink/?LinkId=550986
   3. mailto:mats at wichmann.us
   4. mailto:tutor at python.org