Parse output to get a list in python

Question

[u'10.57518117688789', u'43.17174576695126', u'0 10.57512669810526', u'43.17172389657181', u'0 10.57509460784044', u'43.17169116727101', u'0']

I need to turn this into a list of latitudes and longitudes that are in order from 1st to last. The first element being latitude and the second being longitude. I don't need the u or the '0'.

Right now, I'm just printing them, but this method needs to return a list of coordinates in order.

def get_coord_list_from_earth(filename):

    filename = str(filename)

    data = xml.dom.minidom.parse(filename)

    coordinates = data.getElementsByTagName('coordinates')[0].firstChild.nodeValue
    coordinates = coordinates.strip()

    print coordinates.split(',')

I need it to output a list of lists like this.

[10.57518117688789, 43.17174576695126], [10.57512669810526, 43.17172389657181], [10.57509460784044, 43.17169116727101]

This link is to a sample file this would need to run with

https://www.dropbox.com/s/8heebhnmlwvjtl7/earthFile.xml

It is very unclear what you want us to do with that heterogeneous collection of strings. Please give the expected output for that input. — roippi, Mar 10 '14 at 05:01
In haste you'll find waste :) Can you not simply loop through the records in pairs? — Trent, Mar 10 '14 at 05:09
Is there any meaning to the leading `0 ` in some of the strings, or is it completely safe to ignore that (as in, it will never be something other than 0)? — Blckknght, Mar 10 '14 at 05:11

Sufian Latif · Answer 1 · 2014-03-10T05:31:37.370

2

Can be done easily with zip:

[[float(item[0]), float(item[1])] for item in zip(coordinates[0::2], coordinates[1::2])]

See usage here: http://ideone.com/j4O48c

edited Mar 10 '14 at 05:31

answered Mar 10 '14 at 05:10

Sufian Latif

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Where would that fall in the method? – Will Luce Mar 10 '14 at 05:11
Out of interest - would this die when it hits the final unpaired co-ordinate? – Trent Mar 10 '14 at 05:12
Or `zip(*[iter(coordinates)]*2)` – Blckknght Mar 10 '14 at 05:12
@Trent no it won't, see the link in answer. – Sufian Latif Mar 10 '14 at 05:14
Never had a need to do this, but great to know – Trent Mar 10 '14 at 05:16
@0605002 That's not the output I get when running it through the method. It splits it on every number. 9', u'8'), (u'2', u'5'), (u',', u'4'), (u'3', u'.') – Will Luce Mar 10 '14 at 05:19
@WillLuce I suppose you're running it on a _string_, you should call `zip` upon the 2 lists of coordinates. Once you have a long list of latitudes and longitudes, `zip` will give you a list of lat-long pairs. – Sufian Latif Mar 10 '14 at 05:24
That's awesome. Works as advertised. One more question. These need to be floats, not strings. Can I do that inline? – Will Luce Mar 10 '14 at 05:28
I updated the question with a sample file. – Will Luce Mar 10 '14 at 05:33
@WillLuce I've edited my answer for that, but the `list` in your question has some invalid entries like u'0 10.57512669810526', which fails. – Sufian Latif Mar 10 '14 at 05:38
@0605002 Turns out that 0 is an altitude measurement that outputs from Google Maps. The format is actual Lat, Long, Alt for each coordinate point. Splitting the on ',0' instead of ',' got me closer to what I wanted. Thanks for your help. – Will Luce Mar 10 '14 at 05:52

James Sapam · Accepted Answer · 2014-03-10T06:01:19.280

Could you please check this:

Let me know if that works for you:

import xml.dom.minidom

def get_coord_list_from_earth(filename):

    filename = str(filename)

    data = xml.dom.minidom.parse(filename)

    coordinates = data.getElementsByTagName('coordinates')[0].firstChild.nodeValue
    coordinates = str(coordinates.strip())

    lol = list()
    ls = coordinates.split(',')
    for group_ls in zip(ls[0::2], ls[1::2]):
        f = group_ls[0].split()[-1]
        s = group_ls[1].split()[-1]
        # creating list of tuples, if you are not going to mutate it 
        # then tuple is must more memory efficient then list.
        lol.append((f,s))
    return lol

print get_coord_list_from_earth('test.xml')

Output:

[('-99.96592053692414', '35.92662037784583'), ('-99.96540056429473', 
  '35.92663981781373'), ('-99.96498447443297', '35.92665534578857'), 
 ('-99.96454642236132', '35.9264185376019')]

Parse output to get a list in python

2 Answers2