add a list to a list value python

Question

So I have this class called Data And the class has two attributes; var_names and units is it possible to append list elements of the list (which belongs to attribute units) to each element in the list called var_names? So when I make a new object called myData, the bellow output is possible (so the sublist [1,2,3,4] would be associated to id element?

>>> myData=Data([[1,2,3,4],["a","b","c","d"],
[2.3,2.1,2.5,3.1]],var_names=["id","name","length"])
>>> print myData
id name length
1    a    2.3
2    b    2.1
3    c    2.5
4    d    3.1

Or that's not possible? And be only achieved visually (way of formatting the output)

I'm not sure if that's the case. Because I got this object call and output, now I have to reproduce the code based by the given info: var_names=["id","name","length"] and this doesn't seem to be a namedtuple? — Smeagol2
– Smeagol2, Commented Dec 4, 2012 at 17:19

Abhijit · Accepted Answer · 2012-12-04 18:00:31Z

2

You actually need namedtuple as others have suggested. Here is a possible implementation of what you would need

>>> class Data(object):
    def __init__(self,*args,**kwargs):
        args = args[0]
        var_names = kwargs['var_names']
        self.var_names = namedtuple('Data',var_names)
        self.units = [self.var_names(*e) for e in zip(*args)]
    def __repr__(self):
        fields = [e for e in vars(self.units[0])]
        fmt_string = '{:^10}'*len(fields)
        return '\n'.join(fmt_string.format(*units) for units in self.units)


>>> myData=Data([[1,2,3,4],["a","b","c","d"],
[2.3,2.1,2.5,3.1]],var_names=["id","name","length"])
>>> print myData
    1         a        2.3    
    2         b        2.1    
    3         c        2.5    
    4         d        3.1    
>>>

edited Dec 4, 2012 at 18:00

answered Dec 4, 2012 at 17:50

Abhijit

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1 Comment

Smeagol2 Over a year ago

This sounds good... but what if I'd like to delete 'id' or 'name' Because i've been playing a while with this solution. But I am unable to make a function which would delete values of a selected var for example my_Data.del('lenght') so the out put would contain only id and name.

redrah · Accepted Answer · 2012-12-04 17:36:36Z

0

If I'm understanding you right I think using a dictionary in place of a list for var_names should do what you want. Use collections.OrderedDict if ordering is important.

>>> import collections
>>> var_names = collections.OrderedDict([('id',[1,2,3,4]), 
                                         ('name',['a','b','c','d']), 
                                         ('length',[2.3,2.1,2.5,3.1])])
>>> for name, value in var_names.items(): 
...     print name + ': ' + str(value)
id: [1, 2, 3, 4]
name: ['a', 'b', 'c', 'd']
length: [2.3, 2.1, 2.5, 3.1]

answered Dec 4, 2012 at 17:36

redrah

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