key-value | 易学教程

Swap key with value JSON

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问题 I have an extremely large JSON object structured like this: {A : 1, B : 2, C : 3, D : 4} I need a function that can swap the values with keys in my object and I don't know how to do it. I would need an output like this: {1 : A, 2 : B, 3 : C, 4 : D} Is there any way that I can do this would manually created a new object where everything is swapped? Thanks 回答1: function swap(json){ var ret = {}; for(var key in json){ ret[json[key]] = key; } return ret; } Example here FIDDLE don't forget to turn

Create a Dictionary in xaml?

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问题 Pseudo example: <Window> <Window.Tag> <x:Dictionary KeyType="{x:Type sys:String}" ValueType="{x:Type sys:Int32}"> <sys:DictionaryEntry Entry="{sys:DictionaryEntry Key0, 000}"/> <sys:DictionaryEntry Key="key1" Value="111"/> <sys:DictionaryEntry> <sys:DictionaryEntry.Key> <sys:String>Key2<sys:String> </sys:DictionaryEntry.Key> <sys:DictionaryEntry.Value> <sys:Int32>222</sys:Int32> </sys:DictionaryEntry.Value> </sys:DictionaryEntry> </x:Dictionary /> </Window.Tag> </Window> 回答1: You can't use

How to determine if object is a valid key-value pair in PySpark

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问题 If I have a rdd, how do I understand the data is in key:value format? is there a way to find the same - something like type(object) tells me an object's type. I tried print type(rdd.take(1)) , but it just says <type 'list'> . Let's say I have a data like (x,1),(x,2),(y,1),(y,3) and I use groupByKey and got (x,(1,2)),(y,(1,3)) . Is there a way to define (1,2) and (1,3) as values where x and y are keys? Or does a key has to be a single value? I noted that if I use reduceByKey and sum function

How to iterate over associative arrays in Bash

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Based on an associative array in a Bash script, I need to iterate over it to get the key and value. #!/bin/bash declare -A array array[foo]=bar array[bar]=foo I actually don't understand how to get the key while using a for-in loop. The keys are accessed using an exclamation point: ${!array[@]} , the values are accessed using ${array[@]} . You can iterate over the key/value pairs like this: for i in "${!array[@]}" do echo "key : $i" echo "value: ${array[$i]}" done Note the use of quotes around the variable in the for statement (plus the use of @ instead of * ). This is necessary in case any

JavaScript: Remove duplicates of objects sharing same property value

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问题 I have an array of objects that I would like to trim down based on a specific key:value pair. I want to create an array that includes only one object per this specific key:value pair. It doesn't necessarily matter which object of the duplicates is copied to the new array. For example, I want to trim based on the price property of arrayWithDuplicates , creating a new array that only includes one of each value: var arrayWithDuplicates = [ {"color":"red", "size": "small", "custom": { "inStock":

Designing an EAV database correctly for historical data

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Intro I have been reading about EAV database and most of the short comings seem to be related to really, really, bad EAV designs or difficulty generating reports from the data . Usually when you see people complaining about EAV they are using less than three tables to try to replicate the functionally of separate tables + columns in a RDBMS. Sometimes that means storing everything from decimals to strings in a single TEXT value column. EAV also messes with the safe-guards over data integrity which can be very bad if you are not careful. However, EAV does provide an easy way to track historical

Steps to create and edit a plist file in Xcode

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问题 I want to add key pair values in plist . I dont know how to add the .plist file in XCode. Simply i want to add these details in .plist file named as " Mobile.plist ". Apple - iPhone,iPod,iPad Samsung - Galaxy Y, Galaxy R, Galaxy Z Nokia - Lumina LG - Lg1 ,Lg2, Lg3 I have tried the steps to create a new Mobile.plist file by using this link, http://iphoneincubator.com/blog/tutorial/how-to-create-an-iphone-preferences-file. But, i cant get it exactly. When i tried to use the steps from this link

for each loop in Objective-C for accessing NSMutable dictionary

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问题 I am finding some difficulty in accessing mutable dictionary keys and values in Objective-C. Suppose I have this: NSMutableDictionary *xyz=[[NSMutableDictionary alloc] init]; I can set keys and values. Now, I just want to access each key and value, but I don\'t know the number of keys set. In PHP it is very easy, something as follows: foreach ($xyz as $key => $value) How is it possible in Objective-C? 回答1: for (NSString* key in xyz) { id value = xyz[key]; // do stuff } This works for every

Can't access cookies from document.cookie in JS, but browser shows cookies exist

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问题 I can\'t access any cookie from JavaScript. I need to read some value and send them via JSON for my custom checks. I\'ve tried to access cookies from JS, like it was described at: http://www.w3schools.com/js/js_cookies.asp Get cookie by name As you can see at the code, it\'s seen as clear as a crystal the next: var c_value = document.cookie; When I\'m trying to access the document.cookie value from the Chrome\'s web-debugger, I see only the empty string at the Watch expressions : So I can\'t

Java - How to create new Entry (key, value)

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问题 I\'d like to create new item that similarly to Util.Map.Entry that will contain the structure key , value . The problem is that I can\'t instantiate a Map.Entry because it\'s an interface. Does anyone know how to create a new generic key/value object for Map.Entry? 回答1: You can just implement the Map.Entry<K, V> interface yourself: import java.util.Map; final class MyEntry<K, V> implements Map.Entry<K, V> { private final K key; private V value; public MyEntry(K key, V value) { this.key = key;