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merge!

merge!(collection, others...)

Update collection with pairs from the other collections

Examples

julia> a = Dict("foo" => 0.0, "bar" => 42.0)
Dict{ASCIIString,Float64} with 2 entries:
  "bar" => 42.0
  "foo" => 0.0

julia> b = Dict(utf8("baz") => 17, utf8("bar") => 4711)
Dict{UTF8String,Int64} with 2 entries:
  "bar" => 4711
  "baz" => 17

julia> merge!(a, b);

julia> a
Dict{UTF8String,Float64} with 3 entries:
  "bar" => 4711.0
  "baz" => 17.0
  "foo" => 0.0

julia> a = Dict("foo" => 0.0, "bar" => 42.0)
Dict{ASCIIString,Float64} with 2 entries:
  "bar" => 42.0
  "foo" => 0.0

julia> b = Dict(utf8("baz") => 17, utf8("bar") => 4711)
Dict{UTF8String,Int64} with 2 entries:
  "bar" => 4711
  "baz" => 17

julia> merge!(a, b);

julia> a
Dict{UTF8String,Float64} with 3 entries:
  "bar" => 4711.0
  "baz" => 17.0
  "foo" => 0.0

1. Merge dictionaries:

   julia> dict1 = Dict("a" => 1, "b" => 2);
   julia> dict2 = Dict("b" => 3, "c" => 4);
   julia> merge!(dict1, dict2)
   Dict{String,Int64} with 3 entries:
    "a" => 1
    "b" => 3
    "c" => 4

   This example merges the key-value pairs from dict2 into dict1. If a key already exists in dict1, its value is updated with the value from dict2.

2. Merge arrays:

   julia> arr1 = [1, 2, 3];
   julia> arr2 = [4, 5];
   julia> merge!(arr1, arr2)
   5-element Array{Int64,1}:
   1
   2
   3
   4
   5

   The merge! function can also be used to merge arrays. It appends the elements from arr2 to arr1.

3. Merge multiple dictionaries:

   julia> dict1 = Dict("a" => 1, "b" => 2);
   julia> dict2 = Dict("b" => 3, "c" => 4);
   julia> dict3 = Dict("d" => 5);
   julia> merge!(dict1, dict2, dict3)
   Dict{String,Int64} with 4 entries:
    "a" => 1
    "b" => 3
    "c" => 4
    "d" => 5

   The merge! function can accept multiple dictionaries as arguments. It merges all the key-value pairs from the provided dictionaries into the first dictionary.

Common mistake example:

julia> arr1 = [1, 2, 3];
julia> arr2 = 4;
julia> merge!(arr1, arr2)
ERROR: MethodError: no method matching merge!(::Array{Int64,1}, ::Int64)

In this example, the second argument arr2 is not a collection (array or dictionary), which causes a MethodError. Ensure that the merge! function is used with compatible collection types.

See Also

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