Jquery construct array from django object

Question

I have 20 milliion rows in my table.I am trying to plot graph for timestamp using http://www.jqplot.com/tests/date-axes.php (date vs time) how will jquery handle so much of data to plot it. Two questions:

1.How can I construct an array from the below code:

line1=[['2008-09-30',4], ['2008-10-30',6], ['2008-11-30',5], ['2008-12-30',9], ['2009-01-30',8]];`

2.How can I improvize the code in this case:

def get_data(request):
 cdr = Cdr.objects.values_list('start_of_call',flat=True)
 context_instance=RequestContext(request, {})) 
 return render_to_response('cdr/get_data.html', context_instance=RequestContext(request, {'cdr':cdr}))

template:

<script class="code" type="text/javascript">
$(document).ready(function(){

{% for c in cdr %}
  {{ c|date:"d M Y"}}
{% endfor %}
 How to construct the below array line from for loop or using jquery methods
//var line1=[['2008-09-30',4], ['2008-10-30',6], ['2008-11-30',5], ['2008-12-30',9], ['2009-01-30',8]];

var plot1 = $.jqplot('chart1', [line1], {
title:'Default Date Axis',
axes:{xaxis:{renderer:$.jqplot.DateAxisRenderer}},
series:[{lineWidth:4, markerOptions:{style:'square'}}]
});
});
 </script>

EDIT

  line1=[['2008-09-30',4], ['2008-10-30',6], ['2008-11-30',5], ['2008-12-30',9], ['2009-01-30',8]];`

In the above line 4,6,5,9,8 are the hours

EDIT2

CDR values:

    [datetime.datetime(2012, 9, 13, 15, 54, 52, tzinfo=<UTC>), datetime.datetime(2012, 9, 22, 18, 24, 18, tzinfo=<UTC>), datetime.datetime(2012, 9, 6, 7, 42, 50, tzinfo=<UTC>), datetime.datetime(2012, 9, 7, 21, 27, 13, tzinfo=<UTC>), datetime.datetime(2012, 9, 3, 11, 57, 9, tzinfo=<UTC>), datetime.datetime(2012, 9, 1, 17, 23, 41, tzinfo=<UTC>), datetime.datetime(2012, 9, 15, 6, 14, 33, tzinfo=<UTC>), datetime.datetime(2012, 9, 4, 5, 36, 30, tzinfo=<UTC>), datetime.datetime(2012, 9, 17, 10, 45, 6, tzinfo=<UTC>), datetime.datetime(2012, 10, 1, 3, 1, 17, tzinfo=<UTC>), datetime.datetime(2012, 9, 27, 8, 36, 41, tzinfo=<UTC>), datetime.datetime(2012, 9, 30, 3, 12, 18, tzinfo=<UTC>), datetime.datetime(2012, 9, 18, 4, 8, 49, tzinfo=<UTC>), datetime.datetime(2012, 9, 2, 7, 21, tzinfo=<UTC>), datetime.datetime(2012, 9, 19, 16, 57, 34, tzinfo=<UTC>), datetime.datetime(2012, 9, 17, 17, 14, 49, tzinfo=<UTC>), datetime.datetime(2012, 9, 1, 22, 40, 33, tzinfo=<UTC>), datetime.datetime(2012, 9, 15, 1, 7, 39, tzinfo=<UTC>), datetime.datetime(2012, 9, 22, 17, 11, 45, tzinfo=<UTC>), datetime.datetime(2012, 9, 10, 3, 16, 21, tzinfo=<UTC>), '...(remaining elements truncated)...']

I'm not altogether clear on what you are trying to do. Can you give an example of the values in cdr (and maybe give it a better name). you are trying to build the string line1=[['2008-09-30',4], ['2008-10-30',6],... in your template, right? Why not use JSON to translate Python data into the corresponding JavaScript structure? — scytale
– scytale, Commented Nov 27, 2012 at 11:16
cdr values are 2012-09-28 14:37:22+00:00 ,2012-09-21 14:37:22+00:00,....... — Rajeev
– Rajeev, Commented Nov 27, 2012 at 11:23
can you show cdr as a python pretty-printed data structure? and any reason not to use JSON? — scytale
– scytale, Commented Nov 27, 2012 at 11:33

scytale · Accepted Answer · 2012-11-29 13:53:11Z

3

something like this:

from django.utils import simplejson

def get_data(request):
    cdr = [(x.strftime('%Y-%M-%D'), x.hour) for x in \
            Cdr.objects.values_list('start_of_call',flat=True)]
    return render_to_response('cdr/get_data.html',
                              {'cdr': simplejson.dumps(cdr)},
                              context_instance=RequestContext(request))

The format string in strftime might be a bit off - check it here: http://docs.python.org/2.7/library/datetime.html#strftime-strptime-behavior

by the way your view did some weird things with RequestContext - the above is the more usual style.

template:

line1 = jQuery.parseJSON({{ cdr }})

As for issues with sample size - there's no clear answer - it's going to depend on your network connection, your browser and machine. That siad 20M is very big - consider sampling the dataset to bring it down to a more manageable size - experimentation is going to be the best way.

edited Nov 29, 2012 at 13:53

answered Nov 27, 2012 at 12:12

scytale

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2 Comments

Rajeev Over a year ago

I really didnt want to go this way(using list comprehension).As i have illustrated the problem correctly.I want to really find an optimal solution for the millions of rows.+1 for all the help.Appreciate it

scytale Over a year ago

well you're going to have to iterate over cdr at some stage to convert the datetime objects into (str, int). Anyway you should ask 1 question at a time. Your question didn't ask about an optimal solution - you asked how to construct a JS array from your Python datastructure and secondly how to "improvize" some code, which I understood to mean how to alter your view to pass that datastructure. if you want to know how to optimise the code then you should ask a new question.

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