How to Find Array/Dictionary Value Using Key

Get value of a key from a dictionary array JavaScript

This should help:

const car = [{id: "1", brand: "Opel"}, {id: "2", brand: "Haima"},{id: "3", brand: "Toyota"}];
const brands = car.map(({ brand }) => brand);

Find key-value pair in an array of dictionaries

The following works. You can iterate through the items of each array comparing them to the items in the other:

for item1 in arrayOne {
    for item2 in arrayTwo {
        if item1 == item2 {
            println("found a dictionary common to both arrays")
        }
    }
}

Searching for common key/value pairs in the two arrays:

for dict1 in arrayOne {
    for (key, value) in dict1 {
        for dict2 in arrayTwo {
            if dict2[key] == value {
                println("found \(key):\(value) in both arrays")
            }
        }
    }
}

And if you're searching for a particular key:

let key = "title"

for dict1 in arrayOne {
    if let value = dict1[key] {
        for dict2 in arrayTwo {
            if dict2[key] == value {
                println("found \(key):\(value) in both arrays")
            }
        }
    }
}

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You can write your own arrayContains function that takes the types you need:

func arrayContains(array:[[String:String]], value:[String:String]) -> Bool {
    for item in array {
        if item == value {
            return true
        }
    }
    return false
}

And then use it to find the values you want:

// Save all of the dictionaries from the first array that aren't in the second array

var newArray:[[String:String]] = []

for item in arrayOne {
    if !arrayContains(arrayTwo, item) {
        newArray.append(item)
    }
}

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To search the array for a particular key/value pair:

func arrayContains(array:[[String:String]], #key: String, #value: String) -> Bool {
    for dict in array {
        if dict[key] == value {
            return true
        }
    }
    return false
}

let result = arrayContains(arrayTwo, key: "title", value: "Alien!")

In Python, how do I find keys in an array of dictionaries where the values are the same?

As suggested in other answers, create a master dictionary that groups each key, then check their uniqueness.

# all keys are the same, so get the list
keys = array_of_dicts[0].keys()

# collapse values into a single dictionary
value_dict = {k: set(d[k] for d in array_of_dicts) for k in keys}

# get list of all single-valued keys
print([k for k, v in value_dict.items() if len(v) == 1])

Get key values from array of dictionaries

In objective-c

NSMutableArray *c = [[NSMutableArray alloc] init];

for (NSNumber *i in a) {
    BOOL iFound = NO;
    for (NSDictionary *dict in b) {
        if ((NSNumber *)[[dict allKeys] firstObject] == i) {
            iFound = YES;
            [c addObject:(NSString *)[[dict allValues] firstObject]];
        }
    }
    if (!iFound) {
        [c addObject: [NSNull null]];
    }
}
NSLog(@"%@",c);//("<null>",a,b)

In swift

let a = [1,2,3]
let b = [[2:"a"],[3:"b"],[45:"r"],[16:"a"]]
let c = a.map { i in b.first(where: { $0.keys.first == i })?.values.first }
print(c)//[nil, Optional("a"), Optional("b")]

How to find length of dictionary values

Sure. In this case, you'd just do:

length_key = len(d['key'])  # length of the list stored at `'key'` ...

It's hard to say why you actually want this, but, perhaps it would be useful to create another dict that maps the keys to the length of values:

length_dict = {key: len(value) for key, value in d.items()}
length_key = length_dict['key']  # length of the list stored at `'key'` ...

Get key by value in dictionary

There is none. dict is not intended to be used this way.

dictionary = {'george': 16, 'amber': 19}
search_age = input("Provide age")
for name, age in dictionary.items():  # for name, age in dictionary.iteritems():  (for Python 2.x)
    if age == search_age:
        print(name)

Search by value of dict in array

Convert list of dict to dict

d = {x["token"]: x for x in large_list}
d["4kj13"]["value1"]
# 10

How to add values of a key without losing any value in dictionary python when merging two list as dictionary?

Try this:

name = ['A', 'A', 'B', 'B', 'C', 'D', 'D', 'D']
num = [10, 20, 30, 40, 50, 60, 70, 80]
dict = {}
for key, value in zip(name, num):
    if key not in dict:
        dict[key] = value
    else:
        dict[key] += value
print(dict)

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