key-value

问题 I have question about the KeyEventArgs 's KeyCode and KeyData and KeyValue . KeyCode and Keydata are Keys type, but I don't know what the difference between them is. For KeyValue , I don't know what it is -- it has an int type, does it return the char value of the pressed key? I don't have much experience with Key events; any explanation of how they function and how to use them would be greatly appreciated. 回答1: KeyCode contains data for the key that produced the KeyUp or KeyDown event.

问题 What is the most efficient way to get a number of how many distinct objects is stored in mine dynamodb? Such as my objects have ten properties and I want to get a distinct count based on 3 properties. 回答1: In case you need counters it's better to use the AtomicCounters (http://docs.aws.amazon.com/amazondynamodb/latest/developerguide/WorkingWithDDItems.html). In your case, DynamoDB doesn't support out of the box keys composed out of 3 attributes, unless you concatenate them, so the option

问题 If I have a dictionary with the following key/value "foo"/"bar" and declared [dictionary setObject:@"baz" forKey:@"foo"]; would this replace the current key value pair with "foo"/"baz" and delete "foo"/"bar"? 回答1: The behave of an NSMutableDictionary (as any common hash table) is that if it does not exists it creates a new key/value pair, if it already exits it will replace the existing value with the new one. 回答2: The documentation here; http://developer.apple.com/library/mac/#documentation

问题 I'm having an associative array named $questions . For your reference I'm printing out first four elements from this array. The actual array is quite large but all the array elements are similar as the elements printed below: Array ( [0] => Array ( [question_id] => 33185 [question_parent_id] => 0 [question_subject_id] => 4 [question_topic_id] => 503 [question_directions] => [question_text] => Two gases are at 300 K and 350 K respectively Ratio of average kinetic energy of their molecules is

问题 I'm using key value observing to perform specific actions whenever certain properties are changed (e.g., relayout subviews of a custom UIView whenever its frame or bounds change). Is there any way to see who (i.e., what function) is triggering this change? Putting a breakpoint in my observeValueForKeyPath:ofObject:change:context: doesn't help because I don't think I can see who caused the change to frame or bounds that caused KVO to be triggered. In my specific example, I can't figure out who

问题 I am currently trying to get the index of a value from a dictionary and unsure what to try. My dictionary is: midi2notes = { 'c':("0","12","24","36","48","60","72","84","96","108","120"), 'des':("1","13","25","37","49","61","73","85","97","109","121"), 'd':("2","14","26","38","50","62","74","86","98","110","122"), 'ees':("3","15","27","39","51","63","75","87","99","111","123"), 'e':("4","16","28","40","52","64","76","88","100","112","124"), 'f':("5","17","29","41","53","65","77","89","101",

问题 Supose my dictionary: mydict = [{"red":6}, {"blue":5}, {"red":12}] This is what I've done so far: for key, value in mydict() : if key == mydict.keys(): key[value] += value else: print (key, value) I don't think I'm getting it quite right (been stuck for hours), but I want the output to look like this: blue 5 red 18 or red 18 blue 5 回答1: I do not recommend this since it results a messy design: class MyDict(dict): def __setitem__(self, key, value): if key in self: super().__setitem__(key, self

问题 I have some information that needs to be stored in internal memory. I will like to store in the form of key-value pairs the way its done in SharedPreferences. I was thinking of creating JsonObject and saving and retrieving in that way. Is there any other way that we can save the data in internal memory in the form of key-value pairs? 回答1: Th standard java way of storing Object data is to use Serialization - that is what it is there for. In Most cases implementing Serializable is fairly

问题 I'd like to move from the SQL approach to the Key Value approach, because I deal with "big data" and would like to benefit from systems like DynamoDB, Riak or Cassandra. It's quite easy when the data is unrelated, thus one have a document based approach (a primary key + data, but no relations). I'd appreciate any theoretical or academic input on how to model my data. 回答1: I've been using NoSQL in the last 4 years and this is just what I think, what I learnt ... my personal golden rules.

问题 I have a set of values which need to be shuffled when needed. I don't know which variable type is best for me. Data is actually based on key-value structure.Like; 100 "white" 200 "black" 300 "red" and like that. What I want to do is to change the key-value pairs according to I don't know yet, some algorithm.But they need to be shuffled like this, but shuffling need to be not random , so I can revert data when I need. 100 "red" 200 "white" 300 "black" I don't really know how my approach should