:description: mergedeep: A deep merge function for 🐍.
# [mergedeep](https://pypi.org/project/mergedeep/)
`eval_rst
Version |version|
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A deep merge function for 🐍.
## Installation
`bash
$ pip install mergedeep
`
## Usage
`text
merge(destination: MutableMapping, *sources: Mapping, strategy: Strategy = Strategy.REPLACE) -> MutableMapping
`
Deep merge without mutating the source dicts.
```python3 from mergedeep import merge
a = {“keyA”: 1} b = {“keyB”: {“sub1”: 10}} c = {“keyB”: {“sub2”: 20}}
merged = merge({}, a, b, c)
print(merged) # {“keyA”: 1, “keyB”: {“sub1”: 10, “sub2”: 20}} ```
Deep merge into an existing dict. ```python3 from mergedeep import merge
a = {“keyA”: 1} b = {“keyB”: {“sub1”: 10}} c = {“keyB”: {“sub2”: 20}}
merge(a, b, c)
print(a) # {“keyA”: 1, “keyB”: {“sub1”: 10, “sub2”: 20}} ```
### Merge strategies:
Replace (default)
> Strategy.REPLACE
``python3 # When `destination and source keys are the same, replace the destination value with one from source (default).
# Note: with multiple sources, the last (i.e. rightmost) source value will be what appears in the merged result.
from mergedeep import merge, Strategy
dst = {“key”: [1, 2]} src = {“key”: [3, 4]}
merge(dst, src, strategy=Strategy.REPLACE) # same as: merge(dst, src)
print(dst) # {“key”: [3, 4]} ```
Additive
> Strategy.ADDITIVE
``python3 # When `destination and source values are both the same additive collection type, extend destination by adding values from source. # Additive collection types include: list, tuple, set, and Counter
# Note: if the values are not additive collections of the same type, then fallback to a REPLACE merge.
from mergedeep import merge, Strategy
dst = {“key”: [1, 2], “count”: Counter({“a”: 1, “b”: 1})} src = {“key”: [3, 4], “count”: Counter({“a”: 1, “c”: 1})}
merge(dst, src, strategy=Strategy.ADDITIVE)
print(dst) # {“key”: [1, 2, 3, 4], “count”: Counter({“a”: 2, “b”: 1, “c”: 1})} ```
Typesafe replace
> Strategy.TYPESAFE_REPLACE or Strategy.TYPESAFE
``python3 # When `destination and source values are of different types, raise TypeError. Otherwise, perform a REPLACE merge.
from mergedeep import merge, Strategy
dst = {“key”: [1, 2]} src = {“key”: {3, 4}}
merge(dst, src, strategy=Strategy.TYPESAFE_REPLACE) # same as: Strategy.TYPESAFE # TypeError: destination type: <class ‘list’> differs from source type: <class ‘set’> for key: “key” ```
Typesafe additive
> Strategy.TYPESAFE_ADDITIVE
``python3 # When `destination and source values are of different types, raise TypeError. Otherwise, perform a ADDITIVE merge.
from mergedeep import merge, Strategy
dst = {“key”: [1, 2]} src = {“key”: {3, 4}}
merge(dst, src, strategy=Strategy.TYPESAFE_ADDITIVE) # TypeError: destination type: <class ‘list’> differs from source type: <class ‘set’> for key: “key” ```
## License
MIT © [Travis Clarke](https://blog.travismclarke.com/)