检查python列表中是否存在条目并添加元素

Question

I have two python list of the form

list1 = [('TGFB1', 'TGFB1', 1), ('TGFB1', 'CRP', 0.4),('BRCA2', 'TP53', 0.3)]
list2 = [('BRCA1', 'TP53', 2), ('TGFB1', 'CRP', 0.4),('BRCA2', 'TP53', 0.3)]

I need to check whether each entry in list2 is present in list1 . If present add the integer part and store in a new list. If not present just append that entry to the newly created list. So here my newly created list3 should look like

list3 = [('TGFB1', 'TGFB1', 1), ('TGFB1', 'CRP', 0.8),('BRCA2', 'TP53', 0.6),('BRCA1', 'TP53', 2) ]

Answer 1

Following my above comment, this is what you might want:

from copy import copy

d3 = copy(dict(((x, y), z) for x, y, z in list1))
d2 = dict(((x, y), z) for x, y, z in list2)

for key, value in d2.iteritems():
    d3[key] = (d3[key] if key in d3 else 0.0) + value

If you do really want to turn d3 then back to a list of the same structure use:

list3 = [key + (value,) for key, value in d3.iteritems()]

Answer 2

This is a more complicated version of something that I often do. Usually, I don't care about order and just throw stuff into a dict. Or sometimes I order by key so the initial order doesn't matter.

How about an OrderedDict (python2.7+):

from collections import OrderedDict

list1 = [('TGFB1', 'TGFB1', 1), ('TGFB1', 'CRP', 0.4),('BRCA2', 'TP53',0.3)]
list2 = [('BRCA1', 'TP53',2), ('TGFB1', 'CRP', 0.4),('BRCA2', 'TP53',0.3)]

d=OrderedDict()
for i in list1:
    d[i[0:2]]=i[2]
for i in list2:
    if i[0:2] in d:
        d[i[0:2]]+=i[2]
    else:
        d[i[0:2]]=i[2]
list3=[k+(v,) for k,v in d.items()]
print(list3)