Comparing nested list of tuples

Question

Hi please how can I loop through lst2, check for the matching ones and the sum up the value of v in the in the corresponding dictionary.

i.e. if the elements of ('1','2') in lst2 matches the '1', '2' in lst1, get the value of v ie 5 and add the v values for all the tuples in that list of list.

lst1 = [('1','2',{"v" : 5, "a" : 3}),('7','9',{"v" : 7, "a" : 3}),('3','4',{"v" : 4, "a" : 3}),('1','6',{"v" : 0, "a" : 3}),('2','9',{"v" : 4, "a" : 3})]

lst2 = [[('1','2'),('2','9')], [('1','6'),('7','9')]]

output should be vol = 5 + 4 = 9 for [('1','2'),('2','9')]

please I tried this and it did give the desired output. Please help

vol = []
f = 0.0
for b in lst2:
    if  float(b[0][0]) == float(lst1[0][0]) and float(b[0][0])== float(lst1[0][1]):
        f = f + float(lst1[0][0][v])
        vol.append(f)

For a start, I would suggest changing lst1 to a dictionary with the format {('1', '2'): {'v': 5, 'a': 3}, ('7', '9'): {'v': 7, 'a': 3}} (and so on for the other elements). — Andrew Clark
– Andrew Clark, Commented May 1, 2014 at 21:48
sorry about that I just updated. @F.J that's the data format for the project i am working on. Thanks — Nobi
– Nobi, Commented May 1, 2014 at 21:57

Padraic Cunningham · Accepted Answer · 2014-05-02 00:13:07Z

1

lst1 = [('1','2',{"v" : 5, "a" : 3}),('7','9',{"v" : 7, "a" : 3}),('3','4',{"v" : 4, "a" : 3}),('1','6',{"v" : 0, "a" : 3}),('2','9',{"v" : 4, "a" : 3})]

lst2 = [[('1','2'),('2','9')], [('1','6'),('7','9')]]
vol = [] 

for elem in lst2:
    for sub_e in elem:
        for l in lst1:
            if  l[0:2] == sub_e:
                vol.append(l[2]["v"])
 In [4]: print vol
 [5, 4, 0, 7]

 In [5]: print sum(vol)
 16


To pair the output:

pairs=[]
for i in xrange(0,len(vol),2) :
    pairs.append([vol[i],vol[i+1]])
In [10]: pairs
Out[10]: [[5, 4], [0, 7]]

# even and odd length lists
pairs=[]
vol_it = iter(vol)
for i,j in zip(vol_it, vol_it):
   pairs.append([i,j])
if len(vol) %2 ==1:
    pairs.append([vol[-1]])

In [28]:  vol=[1,2,3,4,5,6]

In [29]: pairs
Out[30]: [[1, 2], [3, 4], [5, 6]]

In[31]: vol=[1,2,3,4,5]
In [31]: pairs
Out[31]: [[1, 2], [3, 4], [5]]


using  itertools:

from itertools import izip_longest
def grouper(iterable, n, fillvalue=None):
    args = [iter(iterable)] * n
    return izip_longest(fillvalue=fillvalue, *args)
print [[x[0],x[1]]for x in (grouper(vol,2)) ]

Is this what you are after?

In [6]: paste
lst1 = [('1','2',{"v" : 5, "a" : 3}),('7','9',{"v" : 7, "a" : 3}),('3','4',{"v" : 4, "a" : 3}),('1','6',{"v" : 0, "a" : 3}),('2','9',{"v" : 4, "a" : 3})]

lst2 = [[('1','2'),('2','9')], [('1','6'),('7','9')]]
vol = [] 

for elem in lst2:
    for sub_e in elem:
        for l in lst1:
            if  l[0:2] == sub_e:
                vol.append(l[2]["v"])

## -- End pasted text --

In [7]: print sum(vol)
16

In [8]: print vol
[5, 4, 0, 7]

edited May 2, 2014 at 0:13

answered May 1, 2014 at 22:11

Padraic Cunningham

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7 Comments

Nobi Over a year ago

please this gives this error: Traceback (most recent call last): File "C:/Users/AMAMIFE/Desktop/obi/nnnnnnnnnn.py", line 160, in <module> if l[0:2] == sub_e: TypeError: 'int' object has no attribute 'getitem'

Padraic Cunningham Over a year ago

@Nobi I added my output from ipython.

Nobi Over a year ago

Sorry @padraic, but is there a way to have the output of vol be like this [[5,4], [0,7]] rather than [5,4,0,7]. Thanks

Nobi Over a year ago

I really appreciate your help

Padraic Cunningham Over a year ago

@Nobi added code that will handle both even and odd length lists.

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