I have two lists in Python.
list1 = ['a','a','b','a','c','b','c','a','d','a','b']
list2 = ['1','2','21','12','1','32','11','12','21','3','31']
I have to group the similar elements in list1. The corresponding elements in list2 should also get grouped based on this. Output should be this:
list1 = [['a','a','a','a','a'],['b','b','b'],['c','c'],['d']]
list2 = [['1','2','12','12','3'],['21','32','31'],['1','11'],['21']]
What is the best way to do this?
If you do not care about the order of elements in the first list, you may use defaultdict:
In [7]: from collections import defaultdict
In [8]: from itertools import izip
In [9]: res = defaultdict(list)
In [10]: for k, v in izip(list1, list2):
....: res[k].append(v)
....:
In [11]: print(res)
defaultdict(<type 'list'>, {'a': ['1', '2', '12', '12', '3'], 'c': ['1', '11'], 'b': ['21', '32', '31'], 'd': ['21']})
In [12]: res.items()
Out[12]:
[('a', ['1', '2', '12', '12', '3']),
('c', ['1', '11']),
('b', ['21', '32', '31']),
('d', ['21'])]
This code worked for me:
groups = list(set(list1))
list1_tmp, list2_tmp = [], []
for char in groups:
list1_tmp.append([])
list2_tmp.append([])
for i in range(len(list1)):
list1_tmp[groups.index(list1[i])].append(list1[i])
list2_tmp[groups.index(list1[i])].append(list2[i])
list1 = list1_tmp
list2 = list2_tmp
The output should be valid as well for any other similar input.
This code should do it:
final_list1 = []
final_list2 = []
for distinct in sorted(list(set(list1))):
index = 0
distinct_list1 = []
distinct_list2 = []
for element in list1:
if element == distinct:
distinct_list1.append(element)
distinct_list2.append(list2[index])
index += 1
final_list1.append(distinct_list1)
final_list2.append(distinct_list2)
list1 = final_list1
list2 = final_list2
This will give you exactly the output you asked for. If you don't really care about the output, there are probably better ways as @soon proposed.
Here's a (kind of ugly) implementation that would do the trick:
list1 = ['a','a','b','a','c','b','c','a','d','a','b']
list2 = ['1','2','21','12','1','32','11','12','21','3','31']
def transform(in_list, other_list):
if len(in_list) != len(other_list):
raise ValueError("Lists must have the sema length!")
out_list = list()
out_other_list = list()
for i, c in enumerate(in_list):
for inner_list, inner_other_list in zip(out_list, out_other_list):
if c in inner_list:
inner_list.append(c)
inner_other_list.append(other_list[i])
break
else:
out_list.append([c])
out_other_list.append([other_list[i]])
return out_list, out_other_list
print transform(list1, list2)
Though I personally like soon's answer,This one successfully retrieve your desired output.
lst= sorted(zip(list1,list2),key=lambda x:x[0])
intList=[]
initial=lst[0][0]
count=0
for index,value in enumerate(lst):
if value[0]==initial:
continue
else:
intList.append(lst[count:index])
initial=value[0]
count=index
finList1=[[a for a,b in innerList] for innerList in intList]
finList2=[[b for a,b in innerList] for innerList in intList]
