deepdiff
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deepdiff is a structured data differ that aims for near-linear time complexity. It's intended to calculate differences & apply patches to structured data ranging from 0-500MBish of encoded JSON.
Diffing structured data carries additional complexity when compared to the standard unix diff utility, which operates on lines of text. By using the structure of data itself, deepdiff is able to provide a rich description of changes that maps onto the structure of the data itself. deepdiff ignores semantically irrelevant changes like whitespace, and can isolate changes like column changes to tabular data to only the relevant switches
Most algorithms in this space have quadratic time complexity, which from our testing makes them very slow on 3MB JSON documents and unable to complete on 5MB or more. deepdiff currently hovers around the 0.9Sec/MB range on 4 core processors
Instead of operating on JSON directly, deepdiff operates on document trees consisting of the go types created by unmarshaling from JSON, which are two complex types:
map[string]interface{}
[]interface{}
and five scalar types:
string, int, float64, bool, nil
By operating on native go types deepdiff can compare documents encoded in different formats, for example decoded CSV or CBOR.
deepdiff is based off an algorithm designed for diffing XML documents outlined in
Detecting Changes in XML Documents by Grégory Cobéna & Amélie Marian
It's been adapted to fit purposes of diffing for Qri: https://github.com/qri-io/qri, folding in parallelism primitives afforded by the go language
deepdiff also includes a tool for applying patches, see documentation for details.
Project Status:
:construction_worker_woman: :construction_worker_man: This is a very new project that hasn't been properly vetted in testing enviornments. Issues/PRs welcome & appriciated. :construction_worker_woman: :construction_worker_man:
Benchmarks
Run on a 4 core MacBook Pro:
$ go test -bench . --run XXX -v --benchmem
goos: darwin
goarch: amd64
pkg: github.com/qri-io/deepdiff
BenchmarkDiff1-4 20000 88167 ns/op 13324 B/op 496 allocs/op
BenchmarkDiffDatasets-4 5000 241119 ns/op 53367 B/op 1614 allocs/op
BenchmarkDiff5MB-4 1 4357009141 ns/op 783217944 B/op 29952860 allocs/op
PASS
ok github.com/qri-io/deepdiff 8.369s
Getting Involved
We would love involvement from more people! If you notice any errors or would like to submit changes, please see our
Contributing Guidelines.
Basic Usage
Here's a quick example pulled from the godoc:
package main
import (
"encoding/json"
"fmt"
"github.com/qri-io/deepdiff"
)
var aJSON = []byte(`{
"a": 100,
"foo": [1,2,3],
"bar": false,
"baz": {
"a": {
"b": 4,
"c": false,
"d": "apples-and-oranges"
},
"e": null,
"g": "apples-and-oranges"
}
}`)
var bJSON = []byte(`{
"a": 99,
"foo": [1,2,3],
"bar": false,
"baz": {
"a": {
"b": 5,
"c": false,
"d": "apples-and-oranges"
},
"e": "thirty-thousand-something-dogecoin",
"f": false
}
}`)
func main() {
var a, b interface{}
if err := json.Unmarshal(aJSON, &a); err != nil {
panic(err)
}
if err := json.Unmarshal(bJSON, &b); err != nil {
panic(err)
}
diffs, err := deepdiff.Diff(a, b)
if err != nil {
panic(err)
}
change, err := FormatPretty(diffs)
if err != nil {
panic(err)
}
fmt.Println(change)
}
License
The deepdiff library is licensed under the GNU Lesser General Public License v3.0