Mixing
MurmurHash3 - Java and Python return different results on long input
I'm using a Java version of MurMurHash3 developed by Google (google.common.hash.HashFunction and google.common.hash.Hashing) to create n independent hash functions (using n different seeds) to hash an ID as long. Here a snippet of the code:
for(int i=0; i<seeds.length;i++){
signature[i] = hash(id, seeds[i]);
}
private long hash(int id, int seed){
HashFunction hf = Hashing.murmur3_128(seed);
long signature = hf.hashLong((long)id).asLong();
I've tried to replicate the above code in Python 2.7 using mmh3 (https://pypi.org/project/mmh3/) but the Python version accept only strings as input (or NumPy int) and using the same seed return a different result. Here a snippet of the code:
def create_signature(self, id):
v = np.int64(id)
signature =
for i in range(len(self.__seeds)):
h = mmh3.hash128(v, self.__seeds[i], signed=True)
signature.append(h)
return signature
Applying mmh3 library on a set of different IDs, there are also lots of collisions (no collisions with the Java version instead). Is there a way to get the same results of Java version with Python?
java python hash murmurhash
asked Nov 21 '18 at 11:30
DanieleDaniele
203
add a comment |
I'm using a Java version of MurMurHash3 developed by Google (google.common.hash.HashFunction and google.common.hash.Hashing) to create n independent hash functions (using n different seeds) to hash an ID as long. Here a snippet of the code:
for(int i=0; i<seeds.length;i++){
signature[i] = hash(id, seeds[i]);
}
private long hash(int id, int seed){
HashFunction hf = Hashing.murmur3_128(seed);
long signature = hf.hashLong((long)id).asLong();
I've tried to replicate the above code in Python 2.7 using mmh3 (https://pypi.org/project/mmh3/) but the Python version accept only strings as input (or NumPy int) and using the same seed return a different result. Here a snippet of the code:
def create_signature(self, id):
v = np.int64(id)
signature =
for i in range(len(self.__seeds)):
h = mmh3.hash128(v, self.__seeds[i], signed=True)
signature.append(h)
return signature
Applying mmh3 library on a set of different IDs, there are also lots of collisions (no collisions with the Java version instead). Is there a way to get the same results of Java version with Python?
java python hash murmurhash
asked Nov 21 '18 at 11:30
DanieleDaniele
203
Not sure if this is it butmmh3seems to be designed to work with strings, so it could be that is computing the hash ofstr(id). Try withh = mmh3.hash128(id.to_bytes(8, byteorder='little'), self.__seeds[i], signed=True)and see if that makes a difference.
– jdehesa
Nov 21 '18 at 12:21
add a comment |
I'm using a Java version of MurMurHash3 developed by Google (google.common.hash.HashFunction and google.common.hash.Hashing) to create n independent hash functions (using n different seeds) to hash an ID as long. Here a snippet of the code:
for(int i=0; i<seeds.length;i++){
signature[i] = hash(id, seeds[i]);
}
private long hash(int id, int seed){
HashFunction hf = Hashing.murmur3_128(seed);
long signature = hf.hashLong((long)id).asLong();
I've tried to replicate the above code in Python 2.7 using mmh3 (https://pypi.org/project/mmh3/) but the Python version accept only strings as input (or NumPy int) and using the same seed return a different result. Here a snippet of the code:
def create_signature(self, id):
v = np.int64(id)
signature =
for i in range(len(self.__seeds)):
h = mmh3.hash128(v, self.__seeds[i], signed=True)
signature.append(h)
return signature
Applying mmh3 library on a set of different IDs, there are also lots of collisions (no collisions with the Java version instead). Is there a way to get the same results of Java version with Python?
java python hash murmurhash
asked Nov 21 '18 at 11:30
DanieleDaniele
203
I'm using a Java version of MurMurHash3 developed by Google (google.common.hash.HashFunction and google.common.hash.Hashing) to create n independent hash functions (using n different seeds) to hash an ID as long. Here a snippet of the code:
for(int i=0; i<seeds.length;i++){
signature[i] = hash(id, seeds[i]);
}
private long hash(int id, int seed){
HashFunction hf = Hashing.murmur3_128(seed);
long signature = hf.hashLong((long)id).asLong();
I've tried to replicate the above code in Python 2.7 using mmh3 (https://pypi.org/project/mmh3/) but the Python version accept only strings as input (or NumPy int) and using the same seed return a different result. Here a snippet of the code:
def create_signature(self, id):
v = np.int64(id)
signature =
for i in range(len(self.__seeds)):
h = mmh3.hash128(v, self.__seeds[i], signed=True)
signature.append(h)
return signature
Applying mmh3 library on a set of different IDs, there are also lots of collisions (no collisions with the Java version instead). Is there a way to get the same results of Java version with Python?
java python hash murmurhash
java python hash murmurhash
asked Nov 21 '18 at 11:30
DanieleDaniele
203
asked Nov 21 '18 at 11:30
DanieleDaniele
203
asked Nov 21 '18 at 11:30
DanieleDaniele
203
asked Nov 21 '18 at 11:30
DanieleDaniele
203
asked Nov 21 '18 at 11:30
DanieleDaniele
203
203
Not sure if this is it butmmh3seems to be designed to work with strings, so it could be that is computing the hash ofstr(id). Try withh = mmh3.hash128(id.to_bytes(8, byteorder='little'), self.__seeds[i], signed=True)and see if that makes a difference.
– jdehesa
Nov 21 '18 at 12:21
add a comment |
Not sure if this is it butmmh3seems to be designed to work with strings, so it could be that is computing the hash ofstr(id). Try withh = mmh3.hash128(id.to_bytes(8, byteorder='little'), self.__seeds[i], signed=True)and see if that makes a difference.
– jdehesa
Nov 21 '18 at 12:21
Not sure if this is it but
mmh3 seems to be designed to work with strings, so it could be that is computing the hash of str(id). Try with h = mmh3.hash128(id.to_bytes(8, byteorder='little'), self.__seeds[i], signed=True) and see if that makes a difference.– jdehesa
Nov 21 '18 at 12:21
Not sure if this is it but
mmh3 seems to be designed to work with strings, so it could be that is computing the hash of str(id). Try with h = mmh3.hash128(id.to_bytes(8, byteorder='little'), self.__seeds[i], signed=True) and see if that makes a difference.– jdehesa
Nov 21 '18 at 12:21
add a comment |
0
active
oldest
votes
Your Answer
StackExchange.ifUsing("editor", function () {
StackExchange.using("externalEditor", function () {
StackExchange.using("snippets", function () {
StackExchange.snippets.init();
});
});
}, "code-snippets");
StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "1"
};
initTagRenderer("".split(" "), "".split(" "), channelOptions);
StackExchange.using("externalEditor", function() {
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
}
});
function createEditor() {
StackExchange.prepareEditor({
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: true,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: 10,
bindNavPrevention: true,
postfix: "",
imageUploader: {
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
},
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
});
}
});
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f53411153%2fmurmurhash3-java-and-python-return-different-results-on-long-input%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
0
active
oldest
votes
0
active
oldest
votes
active
oldest
votes
active
oldest
votes
Thanks for contributing an answer to Stack Overflow!
- Please be sure to answer the question. Provide details and share your research!
But avoid …
- Asking for help, clarification, or responding to other answers.
- Making statements based on opinion; back them up with references or personal experience.
To learn more, see our tips on writing great answers.
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f53411153%2fmurmurhash3-java-and-python-return-different-results-on-long-input%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Not sure if this is it but
mmh3seems to be designed to work with strings, so it could be that is computing the hash ofstr(id). Try withh = mmh3.hash128(id.to_bytes(8, byteorder='little'), self.__seeds[i], signed=True)and see if that makes a difference.– jdehesa
Nov 21 '18 at 12:21