Python Dictionary Value Error
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Too Many Values To Unpack Python Dictionary
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Valueerror Too Many Values To Unpack In Python
is a community of 6.2 million programmers, just like you, helping each other. Join them; it only takes a minute: Sign up 'too many values to unpack', iterating over a dict. key=>string, value=>list up vote
Keyerror Python Dictionary
112 down vote favorite 19 I am getting the 'too many values to unpack' error. Any idea how I can fix this? first_names = ['foo', 'bar'] last_names = ['gravy', 'snowman'] fields = { 'first_names': first_names, 'last_name': last_names, } for field, possible_values in fields: # error happens on this line python share|improve this question edited Mar 29 '13 at 7:53 jamylak 56.7k11129157 asked Mar 29 '11 at 0:32 tipu 2,61973882 add python keyerror exception a comment| 3 Answers 3 active oldest votes up vote 169 down vote accepted You need to use something like iteritems. for field, possible_values in fields.iteritems(): print field, possible_values See this answer for more information on iterating through dictionaries, such as using items(), across python versions. share|improve this answer edited Feb 28 '13 at 10:45 Cyrille 1,023813 answered Mar 29 '11 at 0:34 Philip Southam 7,30752019 29 As for why you need to do this, iterating over a dictionary iterates through the keys, not the key/value pairs. –Jeff Mercado Mar 29 '11 at 0:35 1 @jeffm that's what confused me. i saw this as a PHP foreach. –tipu Mar 29 '11 at 16:23 add a comment| up vote 26 down vote For Python 3.x iteritems has been removed. Use items instead. for field, possible_values in fields.items(): print(field, possible_values) share|improve this answer edited Jun 24 at 17:31 arielf 2,95111335 answered Mar 3 '15 at 21:48 Meistro 1,0471018 add a comment| up vote 25 down vote You want to use iteritems. This returns an iterator over the dictionary, which gives you a tuple(key, value) >>> for field, values in fields.iteritems(): ... print field, values ... first_names ['foo', 'bar'] last_name ['gravy', 'snowman'] Your problem was that you were
here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss python valueerror too many values to unpack (expected 2) the workings and policies of this site About Us Learn more keyerror 0 python about Stack Overflow the company Business Learn more about hiring developers or posting ads with us Stack python catch keyerror Overflow Questions Jobs Documentation Tags Users Badges Ask Question x Dismiss Join the Stack Overflow Community Stack Overflow is a community of 6.2 million programmers, just like you, helping http://stackoverflow.com/questions/5466618/too-many-values-to-unpack-iterating-over-a-dict-key-string-value-list each other. Join them; it only takes a minute: Sign up I'm getting Key error in python up vote 49 down vote favorite 10 In my python program I am getting this error: KeyError: 'variablename' From this code: path = meta_entry['path'].strip('/'), Can anyone please explain why this is happening? python dictionary share|improve this question edited Jul 15 '15 http://stackoverflow.com/questions/10116518/im-getting-key-error-in-python at 23:50 Eric Leschinski 47.2k24222191 asked Apr 12 '12 at 2:11 lonehangman 4551513 4 Key error generally means the key doesn't exist. So,are you sure 'path' exist.? –RanRag Apr 12 '12 at 2:13 2 Print the contents of meta_entry and ensure the key you want exists. –Makoto Apr 12 '12 at 2:14 add a comment| 5 Answers 5 active oldest votes up vote 84 down vote accepted A KeyError generally means the key doesn't exist. So, are you sure the path key exists? From the official python docs: exception KeyError Raised when a mapping (dictionary) key is not found in the set of existing keys. For example: >>> mydict = {'a':'1','b':'2'} >>> mydict['a'] '1' >>> mydict['c'] Traceback (most recent call last): File "
tour help Tour Start here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the workings and policies of this http://programmers.stackexchange.com/questions/225238/python-if-foo-in-dict-vs-try-dictfoo site About Us Learn more about Stack Overflow the company Business Learn more about hiring developers or posting ads with us Software Engineering Questions Tags Users Badges Unanswered Ask Question _ Software Engineering http://openbookproject.net/thinkcs/python/english3e/dictionaries.html Stack Exchange is a question and answer site for professionals, academics, and students working within the systems development life cycle who care about creating, delivering, and maintaining software responsibly. Join them; it too many only takes a minute: Sign up Here's how it works: Anybody can ask a question Anybody can answer The best answers are voted up and rise to the top Python - 'if foo in dict' vs 'try: dict[foo]' up vote 15 down vote favorite 2 This is less a question about the nature of duck typing and more about staying pythonic, I suppose. First of too many values all - when dealing with dicts, in particular when the structure of the dict is fairly predictable and a given key is not typically present but sometimes is, I first think of two approaches: if myKey in dict: do_some_work(dict[myKey]) else: pass And of course Ye Olde 'forgiveness vs permission' approach. try: do_some_work(dict[myKey]) except KeyError: pass As a journeyman Python guy, I feel like I see the latter preferred a lot, which only feels odd I guess because in the Python docs try/excepts seem to be preferred when there is an actual mistake, as opposed to an, um… absence of success? If the occasional dict does not have key in myDict, and it is known that it will not always have that key, is a try/except contextually misleading? This isn't a programming error, it's just a fact of the data - this dict just didn't have that particular key. This seems particularly important when you look at the try/except/else syntax, which looks to be really useful when it comes to making sure that try isn't catching too many errors. You're able to do something like: try: foo += bar except TypeError: pass else: return some_more_work(foo
which use integers as indices to access the values they contain within them. Dictionaries are yet another kind of compound type. They are Python's built-in mapping type. They map keys, which can be any immutable type, to values, which can be any type (heterogeneous), just like the elements of a list or tuple. In other languages, they are called associative arrays since they associate a key with a value. As an example, we will create a dictionary to translate English words into Spanish. For this dictionary, the keys are strings. One way to create a dictionary is to start with the empty dictionary and add key:value pairs. The empty dictionary is denoted {}: >>> eng2sp = {} >>> eng2sp["one"] = "uno" >>> eng2sp["two"] = "dos" The first assignment creates a dictionary named eng2sp; the other assignments add new key:value pairs to the dictionary. We can print the current value of the dictionary in the usual way: >>> print(eng2sp) {"two": "dos", "one": "uno"} The key:value pairs of the dictionary are separated by commas. Each pair contains a key and a value separated by a colon. Hashing The order of the pairs may not be what was expected. Python uses complex algorithms, designed for very fast access, to determine where the key:value pairs are stored in a dictionary. For our purposes we can think of this ordering as unpredictable. You also might wonder why we use dictionaries at all when the same concept of mapping a key to a value could be implemented using a list of tuples: >>> {"apples": 430, "bananas": 312, "oranges": 525, "pears": 217} {'pears': 217, 'apples': 430, 'oranges': 525, 'bananas': 312} >>> [('apples', 430), ('bananas', 312), ('oranges', 525), ('pears', 217)] [('apples', 430), ('bananas', 312), ('oranges', 525), ('pears', 217)] The reason is dictionaries are very fast, implemented using a technique called hashing, which allows us to access a value very quickly. By contrast, the list of tuples