Python: list in tuple

Question

I have data from open street maps in the format:

</way>
<way id="148531879">
    <nd ref="1616241466"/>
    <nd ref="1616241469"/>
    <nd ref="1616241471"/>
    <nd ref="1616241472"/>
    <nd ref="1616241475"/>
    <nd ref="1616241479"/>
    <nd ref="276928691"/>
    <tag k="highway" v="secondary"/>
    <tag k="lit" v="no"/>
    <tag k="oneway" v="yes"/>
    <tag k="ref" v="L 292"/>
</way>
<way id="10870759">
    <nd ref="96594201"/>
    <nd ref="96594205"/>
    <nd ref="96594209"/>
    <nd ref="96594224"/>
    <tag k="highway" v="residential"/>
    <tag k="maxspeed" v="50"/>
    <tag k="name" v="Rockwellstraße"/>
    <tag k="oneway" v="yes"/>
    <tag k="postal_code" v="38518"/>
</way>
<way id="10522831">
    <nd ref="90664716"/>
    <nd ref="940615687"/>
    <nd ref="2222543788"/>
    <nd ref="940619729"/>
    <nd ref="90664692"/>
    <nd ref="939024170"/>
    <nd ref="298997463"/>
    <tag k="highway" v="residential"/>
    <tag k="name" v="Am Allerkanal"/>
    <tag k="postal_code" v="38518"/>
    <tag k="tracktype" v="grade2"/>
</way>

A single file contains 1000s of similar way ids. I want to store these way ids in a list/tuple, but the problem is that the content in a way id is not fixed.

For example the number of 'nd ref' enteries can be different. I was thinking of storing the way id data into a tuple, and also include a list in each tuple containing nd ref data. Then finally storing all the tuples in a single list. Please suggest whether it is feasible, and will I be able to access all the enteries through looping?

Vivek Pradhan · Accepted Answer · 2013-04-03 10:06:25Z

2

Assuming the way id's have only 2 kind of tags, in this case and , if you want to organize the output in a datastructure, storing the way ids and their content in a list, you could do something like:

For every way id, you could define a tuple of the form

 t = (way_id,[list of nd ref tags],[list of tag k values])

So you will have a tuple for each way id and you could append this tuples into a list as you go. The idea of using a tuple is better because the data is organized better and you can refer to the content of tuples very easily:

t[0] -> gives you the way-id
t[1] -> gives you the list of nd-ref values for that id and so on.

Tuples are immutable data structures, in the sense that once you have defined a tuple(let's say its named 't'). You can not change the contents of the tuple like:

t[0] = 34983948 /*Invalid*/

However tuples can contain mutable elements like lists. The official python documentation on lists and tuples might also come in handy.

answered Apr 3, 2013 at 10:06

Vivek Pradhan

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1 Comment

tanzil Over a year ago

thnx vivek, I will try this approach

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