Merging Dictionary collections in Julia - merge() and merge!() Methods

Last Updated : 25 Apr, 2025

The merge() is an inbuilt function in julia which is used to construct a merged collection from the specified collections.

Syntax: merge(d::AbstractDict, others::AbstractDict...) or merge(combine, d::AbstractDict, others::AbstractDict...) or merge(a::NamedTuple, bs::NamedTuple...) Parameters:

d::AbstractDict: First specified collection.
others::AbstractDict: Second specified collection.
combine: Specified combing operation.
NamedTuple: Specified different tuples..

Returns: It returns the merged collection.

Example 1:

Python

# Julia program to illustrate 
# the use of merge() method

# Getting the merged collection.
a = Dict("a" => 1, "b" => 2)
b = Dict("c" => 3, "b" => 4)
prinln(merge(a, b))

Output: Example 2:

Python

# Julia program to illustrate 
# the use of merge() method

# Getting the merged collection
# along with specified operation 
# over the key's value
a = Dict("a" => 1, "b" => 2)
b = Dict("c" => 3, "b" => 4)
prinln(merge(+, a, b))

Output: Example 3:

Python

# Julia program to illustrate 
# the use of merge() method

# Getting the merged tuple
println(merge((a = 5, b = 10), (b = 15, d = 20)))
println(merge((a = 5, b = 10), (b = 15, c =(d = 20, )), (c =(d = 25, ), )))

# Merging tuple of key-value pairs with
# iteration operation
println(merge((a = 5, b = 10, c = 15), [:b =>20, :d =>25]))

Output:

merge!()

The merge!() is an inbuilt function in julia which is used to update collection with pairs from the other collections.

Syntax: merge!(d::AbstractDict, others::AbstractDict...) or merge!(combine, d::AbstractDict, others::AbstractDict...) Parameters:

d::AbstractDict: First specified collection.
others::AbstractDict: Second specified collection.
combine: Specified combing operation.

Returns: It returns the updated collection with pairs from the other collections.

Example 1:

Python

# Julia program to illustrate 
# the use of merge !() method

# Getting the updated collection with
# pairs from the other collections.
A = Dict("a" => 1, "b" => 2);
B = Dict("b" => 4, "c" => 5);
println(merge !(A, B))

Output:

Dict("c"=>5, "b"=>4, "a"=>1)

Example 2:

Python

# Julia program to illustrate 
# the use of merge !() method

# Getting the updated collection with
# pairs from the other collections
# with + operation
A = Dict("a" => 1, "b" => 2);
B = Dict("b" => 4, "c" => 5);
println(merge !(+, A, B))