python - Get key by value in dictionary - Stack Overflow
There is no easy way to find a key in a list by 'looking up' the value. However, if you know the value, iterating through the keys, you can look up values in the dictionary by the element. If D[element] where D is a dictionary object, is equal to the key you're trying to look up, you can execute some code.
How to check if a value exists in a dictionary? - Stack Overflow
to test if "one" is among the values of your dictionary. In Python 2, it's more efficient to use. "one" in d.itervalues() instead. Note that this triggers a linear scan through the values of the dictionary, short-circuiting as soon as it is found, so this is a lot less …
How to lookup / check a dictionary value by key - Stack Overflow
2012年7月29日 · You can use the following method if you don't want to iterate through the dictionary twice. string value;var result = dict01.TryGetValue("tester", out value) && value.Contains("testing"); Share. Follow. edited Jul 29, 2012 at …
list - Lookup dictionary based on python key - Stack Overflow
2017年11月5日 · Collapse your dictionary. d = {k : v for d in mylist1 for k, v in d.items()} d. {'age': 23, 'color': 'blue', 'model': 'one'} Now, just lookup in constant, O(1) time. d['model'] 'one'. By keeping multiple disjoint dict s in the same list, you're defeating their purpose in the first place.
How to Find Item in Dictionary Collection? - Stack Overflow
Looking things up for a Key is the basic function of a Dictionary. But the key has to exist. The basic safe solution, but one that requires 2 lookups, would be:
Retrieving Dictionary Value Best Practices - Stack Overflow
When you call the Contains method, Dictionary does an internal search to find its index. If it returns true, you need another index search to get the actual value. When you use TryGetValue, it searches only once for the index and if found, it assigns the value to your variable.
python - How to search through dictionaries? - Stack Overflow
2015年1月30日 · I'm new to Python dictionaries. I'm making a simple program that has a dictionary that includes four names as keys and the respective ages as values. What I'm trying to do is that if the user enters the a name, the program checks if it's in the dictionary and if it is, it should show the information about that name. This is what I have so far:
Difference between Lookup () and Dictionary (Of list ())
2012年11月13日 · 117. Interesting that nobody has stated the actual biggest difference (Taken directly from MSDN): A Lookup resembles a Dictionary. The difference is that a Dictionary maps keys to single values, whereas a Lookup maps keys to collections of values. answered Jun 6, 2014 at 6:10. Mladen Mihajlovic.
Time complexity of accessing a Python dict - Stack Overflow
2009年12月26日 · The average time complexity is of course O (1). The best method would be to check and take a look at the hashs of the objects you are using. The CPython Dict uses int PyObject_Hash (PyObject *o) which is the equivalent of hash (o).
Inverse dictionary lookup in Python - Stack Overflow
2010年4月3日 · However if you need to do more than one lookup it will be more efficient to create an inverse dictionary. ivd = {v: k for k, v in d.items ()} If there is a possibility of multiple keys with the same value, you will need to specify the desired behaviour in this case. If your Python is 2.6 or older, you can use.