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Howw to prevent the duplication of any value in a column within a CSV file (python)

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  Howw to prevent the duplication of any value in a column within a CSV file (python) peakgraphicz@gmail.com - 2016-04-26 09:01 -0700
    Re: Howw to prevent the duplication of any value in a column within a CSV file (python) Joel Goldstick <joel.goldstick@gmail.com> - 2016-04-26 12:08 -0400
      Re: Howw to prevent the duplication of any value in a column within a CSV file (python) Adam Davis <peakgraphicz@gmail.com> - 2016-04-26 10:05 -0700
        Re: Howw to prevent the duplication of any value in a column within a CSV file (python) Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2016-04-26 20:10 -0400
    Re: Howw to prevent the duplication of any value in a column within a CSV file (python) Ian Kelly <ian.g.kelly@gmail.com> - 2016-04-26 10:13 -0600
      Re: Howw to prevent the duplication of any value in a column within a CSV file (python) Adam Davis <peakgraphicz@gmail.com> - 2016-04-26 10:00 -0700
        Re: Howw to prevent the duplication of any value in a column within a CSV file (python) Ian Kelly <ian.g.kelly@gmail.com> - 2016-04-26 13:50 -0600
    Re: Howw to prevent the duplication of any value in a column within a CSV file (python) Adam Davis <peakgraphicz@gmail.com> - 2016-04-26 10:05 -0700
      RE: Howw to prevent the duplication of any value in a column within a CSV file (python) Joaquin Alzola <Joaquin.Alzola@lebara.com> - 2016-04-26 19:05 +0000
      Re: Howw to prevent the duplication of any value in a column within a CSV file (python) Ian Kelly <ian.g.kelly@gmail.com> - 2016-04-26 13:51 -0600
        Re: Howw to prevent the duplication of any value in a column within a CSV file (python) Adam Davis <peakgraphicz@gmail.com> - 2016-04-26 13:07 -0700
          Re: Howw to prevent the duplication of any value in a column within a CSV file (python) Ian Kelly <ian.g.kelly@gmail.com> - 2016-04-26 14:19 -0600
            Re: Private message regarding: Howw to prevent the duplication of any value in a column within a CSV file (python) Ian Kelly <ian.g.kelly@gmail.com> - 2016-05-02 07:47 -0600
          Re: Howw to prevent the duplication of any value in a column within a CSV file (python) MRAB <python@mrabarnett.plus.com> - 2016-04-26 21:23 +0100
            Re: Howw to prevent the duplication of any value in a column within a CSV file (python) Adam Davis <peakgraphicz@gmail.com> - 2016-04-26 23:26 -0700
              Re: Howw to prevent the duplication of any value in a column within a CSV file (python) Chris Angelico <rosuav@gmail.com> - 2016-04-27 16:37 +1000
                Re: Howw to prevent the duplication of any value in a column within a CSV file (python) Adam Davis <peakgraphicz@gmail.com> - 2016-04-27 05:23 -0700
                  Re: Howw to prevent the duplication of any value in a column within a CSV file (python) Andrew Ongko <andrew.ongko@gmail.com> - 2016-04-27 19:57 +0700
                    Re: Howw to prevent the duplication of any value in a column within a CSV file (python) darnold <darnold992000@yahoo.com> - 2016-04-27 08:49 -0700
    RE: Howw to prevent the duplication of any value in a column within a CSV file (python) Joaquin Alzola <Joaquin.Alzola@lebara.com> - 2016-04-26 16:07 +0000

#107662 — Howw to prevent the duplication of any value in a column within a CSV file (python)

I am wondering how to make my code function so it does not allow any of the same values to be entered into a column in my CSV file created through python. So I need to read into the CSV file and check if any names have already been entered. If they have, the user must not be allowed to enter this value.

Thanks in advance!

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#107663

On Tue, Apr 26, 2016 at 12:01 PM,  <peakgraphicz@gmail.com> wrote:
> I am wondering how to make my code function so it does not allow any of the same values to be entered into a column in my CSV file created through python. So I need to read into the CSV file and check if any names have already been entered. If they have, the user must not be allowed to enter this value.
>
> Thanks in advance!
> --
> https://mail.python.org/mailman/listinfo/python-list

Show your code and a few lines of your file with useful data.  Show
the result you want

-- 
Joel Goldstick
http://joelgoldstick.com/blog
http://cc-baseballstats.info/stats/birthdays

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#107674

On Tuesday, 26 April 2016 17:09:10 UTC+1, Joel Goldstick  wrote:
> On Tue, Apr 26, 2016 at 12:01 PM,  <peakgraphicz@gmail.com> wrote:
> > I am wondering how to make my code function so it does not allow any of the same values to be entered into a column in my CSV file created through python. So I need to read into the CSV file and check if any names have already been entered. If they have, the user must not be allowed to enter this value.
> >
> > Thanks in advance!
> > --
> > https://mail.python.org/mailman/listinfo/python-list
> 
> Show your code and a few lines of your file with useful data.  Show
> the result you want
> 
> -- 
> Joel Goldstick
> http://joelgoldstick.com/blog
> http://cc-baseballstats.info/stats/birthdays

Here's my section of code:

with open(class_code+".csv", 'a') as csvfile:
        fieldnames = ["Name", "Score 1", "Score 2", "Score 3", "Average"]
        writer = csv.DictWriter(csvfile, fieldnames=fieldnames)
        #writer.writeheader()
        writer.writerow({"Name": name, "Score 1": score1, "Score 2": score2, "Score 3": score3})

It prints when requested as:

Adam,1,0,0,0.3333333333333333
Jake,9,10,6,8.333333333333334
Tom,5,3,3,3.6666666666666665

So basically, if anyone called Adam, Jake or Tom tries the quiz again, it will not let them.
Thanks

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#107694

On Tue, 26 Apr 2016 10:05:00 -0700 (PDT), Adam Davis
<peakgraphicz@gmail.com> declaimed the following:

>Here's my section of code:
>
>with open(class_code+".csv", 'a') as csvfile:
>        fieldnames = ["Name", "Score 1", "Score 2", "Score 3", "Average"]
>        writer = csv.DictWriter(csvfile, fieldnames=fieldnames)
>        #writer.writeheader()
>        writer.writerow({"Name": name, "Score 1": score1, "Score 2": score2, "Score 3": score3})
>
>It prints when requested as:
>
>Adam,1,0,0,0.3333333333333333
>Jake,9,10,6,8.333333333333334
>Tom,5,3,3,3.6666666666666665
>
>So basically, if anyone called Adam, Jake or Tom tries the quiz again, it will not let them.
>Thanks

	Probably not what you want, but...

	I'd drop the CSV file -- create an SQLite3 database with two tables:

TestTaker(*ID*, Name)

and

Scores(*ID*, _testTakerID_, TestID, Score)

where *ID* is the primary key -- autoincrement integer; _testTakeID_ is a
foreign key (the ID of the TestTaker); no need to store the average, you'll
compute that when retrieving data.

	If you set up (_testTakerID_, TestID) as a composite unique key, the
database system will object when you try to add a duplicate of those two
fields. 

	This design is not limited to only three scores (since TestID
identifies which score you can easily add more tests).

	You'd get the average by something like (this is off the cuff, I'd have
to test to get the syntax fully correct):

select TestTaker.Name, avg(Score) from 
TestTake inner join Scores
on TestTaker.ID = Scores.testTakerID
group by TestTaker.ID
order by TestTaker.Name


-- 
	Wulfraed                 Dennis Lee Bieber         AF6VN
    wlfraed@ix.netcom.com    HTTP://wlfraed.home.netcom.com/

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#107665

On Tue, Apr 26, 2016 at 10:01 AM,  <peakgraphicz@gmail.com> wrote:
> I am wondering how to make my code function so it does not allow any of the same values to be entered into a column in my CSV file created through python. So I need to read into the CSV file and check if any names have already been entered. If they have, the user must not be allowed to enter this value.

Assuming the file is reasonably small enough to fit into memory,
create a set and populate it with the values in the column. When the
user enters a new value, check whether it's already in the set.

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#107672

On Tuesday, 26 April 2016 17:14:36 UTC+1, Ian  wrote:
> On Tue, Apr 26, 2016 at 10:01 AM,  <peakgraphicz@gmail.com> wrote:
> > I am wondering how to make my code function so it does not allow any of the same values to be entered into a column in my CSV file created through python. So I need to read into the CSV file and check if any names have already been entered. If they have, the user must not be allowed to enter this value.
> 
> Assuming the file is reasonably small enough to fit into memory,
> create a set and populate it with the values in the column. When the
> user enters a new value, check whether it's already in the set.

That's exactly what I want to do, however, I'm unsure how to check whether it's in the set?

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#107684

On Tue, Apr 26, 2016 at 11:00 AM, Adam Davis <peakgraphicz@gmail.com> wrote:
> On Tuesday, 26 April 2016 17:14:36 UTC+1, Ian  wrote:
>> On Tue, Apr 26, 2016 at 10:01 AM,  <peakgraphicz@gmail.com> wrote:
>> > I am wondering how to make my code function so it does not allow any of the same values to be entered into a column in my CSV file created through python. So I need to read into the CSV file and check if any names have already been entered. If they have, the user must not be allowed to enter this value.
>>
>> Assuming the file is reasonably small enough to fit into memory,
>> create a set and populate it with the values in the column. When the
>> user enters a new value, check whether it's already in the set.
>
> That's exactly what I want to do, however, I'm unsure how to check whether it's in the set?

if value in the_set:
    # Forbid the value.
else:
    # Allow the value.

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#107675

On Tuesday, 26 April 2016 17:01:41 UTC+1, Adam Davis  wrote:
> I am wondering how to make my code function so it does not allow any of the same values to be entered into a column in my CSV file created through python. So I need to read into the CSV file and check if any names have already been entered. If they have, the user must not be allowed to enter this value.
> 
> Thanks in advance!

Here's my section of code:

with open(class_code+".csv", 'a') as csvfile:
        fieldnames = ["Name", "Score 1", "Score 2", "Score 3", "Average"]
        writer = csv.DictWriter(csvfile, fieldnames=fieldnames)
        #writer.writeheader()
        writer.writerow({"Name": name, "Score 1": score1, "Score 2": score2, "Score 3": score3})

It prints when requested as:

Adam,1,0,0,0.3333333333333333
Jake,9,10,6,8.333333333333334
Tom,5,3,3,3.6666666666666665

So basically, if anyone called Adam, Jake or Tom tries the quiz again, it will not let them.
Thanks

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#107683

Just an example. Didn't use the csv but just hope that it helps.

name=[]
name_exist="Dop"

with open("dop.csv") as f:
        for line in f:
                line_split=line.split(',')
                name.append(line_strip[0])
        if name_exist in name:
                print "found name " + name_exist + " Can not append"
        else:
                file = open("dop.csv",'a')
                print "No name found"
                file.write(name_exist)
file.close()

-----Original Message-----
From: Python-list [mailto:python-list-bounces+joaquin.alzola=lebara.com@python.org] On Behalf Of Adam Davis
Sent: 26 April 2016 18:05
To: python-list@python.org
Subject: Re: Howw to prevent the duplication of any value in a column within a CSV file (python)

On Tuesday, 26 April 2016 17:01:41 UTC+1, Adam Davis  wrote:
> I am wondering how to make my code function so it does not allow any of the same values to be entered into a column in my CSV file created through python. So I need to read into the CSV file and check if any names have already been entered. If they have, the user must not be allowed to enter this value.
>
> Thanks in advance!

Here's my section of code:

with open(class_code+".csv", 'a') as csvfile:
        fieldnames = ["Name", "Score 1", "Score 2", "Score 3", "Average"]
        writer = csv.DictWriter(csvfile, fieldnames=fieldnames)
        #writer.writeheader()
        writer.writerow({"Name": name, "Score 1": score1, "Score 2": score2, "Score 3": score3})

It prints when requested as:

Adam,1,0,0,0.3333333333333333
Jake,9,10,6,8.333333333333334
Tom,5,3,3,3.6666666666666665

So basically, if anyone called Adam, Jake or Tom tries the quiz again, it will not let them.
Thanks
--
https://mail.python.org/mailman/listinfo/python-list
This email is confidential and may be subject to privilege. If you are not the intended recipient, please do not copy or disclose its content but contact the sender immediately upon receipt.

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#107685

On Tue, Apr 26, 2016 at 1:05 PM, Joaquin Alzola
<Joaquin.Alzola@lebara.com> wrote:
> Just an example. Didn't use the csv but just hope that it helps.
>
> name=[]
> name_exist="Dop"
>
> with open("dop.csv") as f:
>         for line in f:
>                 line_split=line.split(',')
>                 name.append(line_strip[0])
>         if name_exist in name:
>                 print "found name " + name_exist + " Can not append"
>         else:
>                 file = open("dop.csv",'a')
>                 print "No name found"
>                 file.write(name_exist)
> file.close()

Except that as noted elsewhere in the thread a set would be a better
choice than a list, since checking membership is much faster on a set.

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#107686

On Tuesday, 26 April 2016 20:52:54 UTC+1, Ian  wrote:
> On Tue, Apr 26, 2016 at 1:05 PM, Joaquin Alzola
> <Joaquin.Alzola@lebara.com> wrote:
> > Just an example. Didn't use the csv but just hope that it helps.
> >
> > name=[]
> > name_exist="Dop"
> >
> > with open("dop.csv") as f:
> >         for line in f:
> >                 line_split=line.split(',')
> >                 name.append(line_strip[0])
> >         if name_exist in name:
> >                 print "found name " + name_exist + " Can not append"
> >         else:
> >                 file = open("dop.csv",'a')
> >                 print "No name found"
> >                 file.write(name_exist)
> > file.close()
> 
> Except that as noted elsewhere in the thread a set would be a better
> choice than a list, since checking membership is much faster on a set.

Thanks for your help Ian. I'm a beginner right now, could you instruct me as to how I would create a set?

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#107687

On Tue, Apr 26, 2016 at 2:07 PM, Adam Davis <peakgraphicz@gmail.com> wrote:
> On Tuesday, 26 April 2016 20:52:54 UTC+1, Ian  wrote:
>> On Tue, Apr 26, 2016 at 1:05 PM, Joaquin Alzola
>> <Joaquin.Alzola@lebara.com> wrote:
>> > Just an example. Didn't use the csv but just hope that it helps.
>> >
>> > name=[]
>> > name_exist="Dop"
>> >
>> > with open("dop.csv") as f:
>> >         for line in f:
>> >                 line_split=line.split(',')
>> >                 name.append(line_strip[0])
>> >         if name_exist in name:
>> >                 print "found name " + name_exist + " Can not append"
>> >         else:
>> >                 file = open("dop.csv",'a')
>> >                 print "No name found"
>> >                 file.write(name_exist)
>> > file.close()
>>
>> Except that as noted elsewhere in the thread a set would be a better
>> choice than a list, since checking membership is much faster on a set.
>
> Thanks for your help Ian. I'm a beginner right now, could you instruct me as to how I would create a set?

Create a new set:

    my_set = set()

Add a value to the set:

    my_set.add(value)

Check for membership:

    value in my_set

See also the Python tutorial at
https://docs.python.org/3/tutorial/datastructures.html#sets

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#108007 — Re: Private message regarding: Howw to prevent the duplication of any value in a column within a CSV file (python)

On Mon, May 2, 2016 at 3:52 AM, Adam Davis <peakgraphicz@gmail.com> wrote:
> Hi Ian,
>
> I'm really struggling to implement a set into my code as I'm a beginner,
> it's taking me a while to grasp the idea of it. If I was to show you my code
> so you get an idea of my aim/function of the code, would you be able to help
> me at all?

Sure, although I'd recommend posting it to the list so that others
might also be able to help.

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#107688

On 2016-04-26 21:07, Adam Davis wrote:
> On Tuesday, 26 April 2016 20:52:54 UTC+1, Ian  wrote:
>> On Tue, Apr 26, 2016 at 1:05 PM, Joaquin Alzola
>> <Joaquin.Alzola@lebara.com> wrote:
>> > Just an example. Didn't use the csv but just hope that it helps.
>> >
>> > name=[]
>> > name_exist="Dop"
>> >
>> > with open("dop.csv") as f:
>> >         for line in f:
>> >                 line_split=line.split(',')
>> >                 name.append(line_strip[0])
>> >         if name_exist in name:
>> >                 print "found name " + name_exist + " Can not append"
>> >         else:
>> >                 file = open("dop.csv",'a')
>> >                 print "No name found"
>> >                 file.write(name_exist)
>> > file.close()
>>
>> Except that as noted elsewhere in the thread a set would be a better
>> choice than a list, since checking membership is much faster on a set.
>
> Thanks for your help Ian. I'm a beginner right now, could you instruct me as to how I would create a set?
>
Create a set:

     the_set = set()

Add an item to a set:

     the_set.add(item)

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#107709

On Tuesday, 26 April 2016 21:23:58 UTC+1, MRAB  wrote:
> On 2016-04-26 21:07, Adam Davis wrote:
> > On Tuesday, 26 April 2016 20:52:54 UTC+1, Ian  wrote:
> >> On Tue, Apr 26, 2016 at 1:05 PM, Joaquin Alzola
> >> <Joaquin.Alzola@lebara.com> wrote:
> >> > Just an example. Didn't use the csv but just hope that it helps.
> >> >
> >> > name=[]
> >> > name_exist="Dop"
> >> >
> >> > with open("dop.csv") as f:
> >> >         for line in f:
> >> >                 line_split=line.split(',')
> >> >                 name.append(line_strip[0])
> >> >         if name_exist in name:
> >> >                 print "found name " + name_exist + " Can not append"
> >> >         else:
> >> >                 file = open("dop.csv",'a')
> >> >                 print "No name found"
> >> >                 file.write(name_exist)
> >> > file.close()
> >>
> >> Except that as noted elsewhere in the thread a set would be a better
> >> choice than a list, since checking membership is much faster on a set.
> >
> > Thanks for your help Ian. I'm a beginner right now, could you instruct me as to how I would create a set?
> >
> Create a set:
> 
>      the_set = set()
> 
> Add an item to a set:
> 
>      the_set.add(item)

I understand what you're saying! But where you say: " the_set = set()", what would go within the set brackets?

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#107711

On Wed, Apr 27, 2016 at 4:26 PM, Adam Davis <peakgraphicz@gmail.com> wrote:
> I understand what you're saying! But where you say: " the_set = set()", what would go within the set brackets?

Nothing. The empty parentheses mean "call this with no arguments", and
when you call the set constructor like that, you get back an empty
set.

ChrisA

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#107722

On Wednesday, 27 April 2016 07:37:42 UTC+1, Chris Angelico  wrote:
> On Wed, Apr 27, 2016 at 4:26 PM, Adam Davis <peakgraphicz@gmail.com> wrote:
> > I understand what you're saying! But where you say: " the_set = set()", what would go within the set brackets?
> 
> Nothing. The empty parentheses mean "call this with no arguments", and
> when you call the set constructor like that, you get back an empty
> set.
> 
> ChrisA

Thanks Chris. Where Ian says 'the_set.add(item)', what would be put within item in terms of my codes function/aim? 

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#107723

On Apr 27, 2016 7:25 PM, "Adam Davis" <peakgraphicz@gmail.com> wrote:
>
> On Wednesday, 27 April 2016 07:37:42 UTC+1, Chris Angelico  wrote:
> > On Wed, Apr 27, 2016 at 4:26 PM, Adam Davis <peakgraphicz@gmail.com>
wrote:
> > > I understand what you're saying! But where you say: " the_set =
set()", what would go within the set brackets?
> >
> > Nothing. The empty parentheses mean "call this with no arguments", and
> > when you call the set constructor like that, you get back an empty
> > set.
> >
> > ChrisA
>
> Thanks Chris. Where Ian says 'the_set.add(item)', what would be put
within item in terms of my codes function/aim?

item is name in your case. Since it's the one you care about existing or
not.

It would be like:
Read from csv,
For each row, the_set.add(name)

Now that you have the_set in memory, whenever you want to check whether a
particular name has taken the quiz, just do:

if name in the_set:
    # forbid
else:
    # allow

Regards,
Andrew

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#107729

potential_passengers = ['bob','john','sue','wendy','chris','bob','jen','wendy']
accepted_passengers = set()

for name in potential_passengers:
    print('checking on {}...'.format(name))
    if name not in accepted_passengers:
        accepted_passengers.add(name)
        print('welcome aboard, {}!'.format(name))        
    else:
        print('i am sorry, we have already accepted a {}.'.format(name))
    print()        
            

HTH,
Don         

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#107696

import csv

Use dictionary {key:value}

-----Original Message-----
From: Python-list [mailto:python-list-bounces+joaquin.alzola=lebara.com@python.org] On Behalf Of peakgraphicz@gmail.com
Sent: 26 April 2016 17:01
To: python-list@python.org
Subject: Howw to prevent the duplication of any value in a column within a CSV file (python)

I am wondering how to make my code function so it does not allow any of the same values to be entered into a column in my CSV file created through python. So I need to read into the CSV file and check if any names have already been entered. If they have, the user must not be allowed to enter this value.

Thanks in advance!
--
https://mail.python.org/mailman/listinfo/python-list
This email is confidential and may be subject to privilege. If you are not the intended recipient, please do not copy or disclose its content but contact the sender immediately upon receipt.

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