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The most conventional method to concatenate lists in python is by using the concatenation operator(+). The “+” operator can easily join the whole list behind another list and provide you with the new list as the final output as shown in the below example.
Straightforward way is to run two nested loops – outer loop gives one sublist of lists, and inner loop gives one element of sublist at a time. Each element is appended to flat list object.
One simple and popular way to merge(join) two lists in Python is using the in-built append() method of python. The append() method in python adds a single item to the existing list. It doesn't return a new list of items, instead, it modifies the original list by adding the item to the end of the list.
On what basis should the merging take place? Your question is rather vague. Also, I assume a, b, ..., f are supposed to be strings, that is, 'a', 'b', ..., 'f'.
>>> x = ['a', 'b', 'c', 'd', 'e', 'f', 'g']
>>> x[3:6] = [''.join(x[3:6])]
>>> x
['a', 'b', 'c', 'def', 'g']
Check out the documentation on sequence types, specifically on mutable sequence types. And perhaps also on string methods.
That example is pretty vague, but maybe something like this?
items = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h']
items[3:6] = [''.join(items[3:6])]
It basically does a splice (or assignment to a slice) operation. It removes items 3 to 6 and inserts a new list in their place (in this case a list with one item, which is the concatenation of the three items that were removed.)
For any type of list, you could do this (using the + operator on all items no matter what their type is):
items = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h']
items[3:6] = [reduce(lambda x, y: x + y, items[3:6])]
This makes use of the reduce function with a lambda function that basically adds the items together using the + operator.
just a variation
alist=["a", "b", "c", "d", "e", 0, "g"]
alist[3:6] = [''.join(map(str,alist[3:6]))]
print alist
Of course @Stephan202 has given a really nice answer. I am providing an alternative.
def compressx(min_index = 3, max_index = 6, x = ['a', 'b', 'c', 'd', 'e', 'f', 'g']):
x = x[:min_index] + [''.join(x[min_index:max_index])] + x[max_index:]
return x
compressx()
>>>['a', 'b', 'c', 'def', 'g']
You can also do the following.
x = x[:min_index] + [''.join(x[min_index:max_index])] + x[max_index:]
print(x)
>>>['a', 'b', 'c', 'def', 'g']
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