Question

I’m trying to add whole words from one string to another if they contain a certain character:

mylist = ["hahah", "hen","cool", "breaker", "when"]
newlist = []

for word in mylist:
    store = word          #stores current string
    if 'h' in word:      #splits string into characters and searches for 'h'
        newlist += store #adds whole string to list


print newlist

the result I expect is:

newlist = ["hahah","hen","when"]

but instead I’m getting:

newlist =  ['h', 'a', 'h', 'a', 'h', 'h', 'e', 'n', 'w', 'h', 'e', 'n']

How do I get my expected result?

Answer 1

Use append ^[docs]:

newlist.append(store)

Or shorter (using list comprehension ^[docs]):

newlist = [word for word in mylist if 'h' in word]

---

Why does newlist += store not work?

This is the same as newlist = newlist + store and is extending the existing list (on left side) by all the items in the sequence ^[docs] on the right side. If you follow the documentation, you will find this:

s + t the concatenation of s and t

In Python, not only lists are sequences, but strings are too (a sequence of characters). That means every item of the sequence (→ every character) is appended to the list.