如何在字典列表中拆分字典字符串值以添加新的字典项？

Question

I have a list of dictionaries and in each list there is a key called text with a string value. To each dictionary I want to add a new item which is called first_word which is a split of the string of text to obtain the the code.

For example if I have:

alist =[{'id':1, 'text':'Dogs are great'},

{'id':2, 'text':'Cats are great'},

'id':3, 'text':'Fish are smelly'}]

I would want to add a new field called first_word:

alist =[{'id':1, 'text':'Dogs are great', 'first_word':'Dogs'},

{'id':2, 'text':'Cats are great', 'first_word':'Cats'},

'id':3, 'text':'Fish are smelly', 'first_word':'Fish'}]

The code which I have use to attempt this is below:

for ditem in alist:
    ditem['first_word'] = ditem['text'].split()[0]

however I am receiving the error:

IndexError: list index out of range

How can I do this?

Answer 1

Pass an empty space character to the split method, like :

for ditem in alist:
    ditem['first_word'] = ditem['text'].split(' ', 1)[0]

Use the second argument to .split() to let the splitting stop early in case your strings are big.

Answer 2

Your code works well apart from the typo. You missed a { before the third item.

Jupyter throws this

  File "<ipython-input-17-6aeaa3a052d5>", line 5
    'id':3, 'text':'Fish are smelly'}]
        ^
SyntaxError: invalid syntax

Just amend it

alist =[{'id':1, 'text':'Dogs are great'},
{'id':2, 'text':'Cats are great'},
{'id':3, 'text':'Fish are smelly'}]

for ditem in alist:
    ditem['firstword']=ditem['text'].split()[0]

alist

Output:

[{'id': 1, 'text': 'Dogs are great', 'firstword': 'Dogs'},
 {'id': 2, 'text': 'Cats are great', 'firstword': 'Cats'},
 {'id': 3, 'text': 'Fish are smelly', 'firstword': 'Fish'}]

Answer 3

You have an error in your dictionary. Look at line 3 if a list you're missing a curly brace.

Answer 4

alist =[{'id':1, 'text':'Dogs are great'}, {'id':2, 'text':'Cats are great'}, {'id':3, 'text':'Fish are smelly'}]

def append_kv(dd):
    dd['first_word '] = ''
    return dd

alist = [append_kv(dd) for dd in alist]

Answer 5

There are probably dicts in your list whose 'text' is empty.

You can either sanitize your data or, if you want to ignore the empty texts and add an empty 'first_word' in this case, you could do:

for ditem in alist:
    ditem['first_word'] = ditem['text'].split()[0] if ditem['text'] else ''

Answer 6

The particular IndexError you mentioned should only happen when you try to access a list element that doesn't exist. You have exactly one list access (the list output from ditem['text'].split() , and you're trying to access it's first element, so that list must be empty. This happens precisely when ditem['text'] is empty, which gives us a quick fix: check to see if it's empty.

for ditem in alist:
    t = ditem['text']
    ditem['first_word'] = t.split()[0] if t else None

Answer 7

Putting aside the missing brace, your code works on the input you show.

The only circumstances in which you'd get a list index out of range exception is if text is empty:

In [11]: for ditem in alist:
    ...:     ditem['first_word'] = ditem['text'].split()[0]
    ...:
IndexError: list index out of range

One way to fix this is by explicitly handling empty text:

In [12]: for ditem in alist:
    ...:     ditem['first_word'] = ditem['text'].split()[0] if ditem['text'] else ''
    ...:
    ...: