🕷️ Crawler Inspector

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Raw Queries and Responses

1. Shard Calculation

Query:

Response:

Calculated Shard: 169 (from laksa119)

2. Crawled Status Check

Query:

curl -X POST \
  'http://laksa169.int.ahrefs:8124/' \
  -H 'Content-Type: text/plain' \
  -H 'X-ClickHouse-Database: crawler3' \
  -H 'Authorization: Basic YXBpOg==' \
  -d 'SELECT getAhrefsURLFromUnparsed(src_unparsed) AS found_url, ifNull(toUnixTimestamp(download_stamp), 0) AS crawl_time, ifNull(toUnixTimestamp(props_url_first_seen), 0) AS first_indexed_time, download_http_code AS http_code, src_unparsed AS src_unparsed, src_root_hash AS src_root_hash, history_drop_reason AS history_drop_reason, meta_title AS meta_title, meta_descriptions AS meta_descriptions, attrs_boilerpipe_text AS attrs_boilerpipe_text, attrs_markdown AS attrs_markdown, attrs_readable_markdown AS attrs_readable_markdown, meta_canonical AS meta_canonical FROM crawler3.page_info_local FINAL PREWHERE (src_root_hash, src_unparsed) IN ((getAhrefsRootHashFromUnparsed(getAhrefsUnparsedNoserviceFromURL(\'https://stackoverflow.com/questions/26256488/error-correction-codes-for-correcting-4-error-bits\')), getAhrefsUnparsedNoserviceFromURL(\'https://stackoverflow.com/questions/26256488/error-correction-codes-for-correcting-4-error-bits\'))) FORMAT JSONEachRow'

Response:

{"found_url":"https:\/\/stackoverflow.com\/questions\/26256488\/error-correction-codes-for-correcting-4-error-bits","crawl_time":1760872410,"first_indexed_time":1436805959,"http_code":200,"src_unparsed":"com,stackoverflow!\/questions\/26256488\/error-correction-codes-for-correcting-4-error-bits s443","src_root_hash":"714406497480128969","history_drop_reason":null,"meta_title":"Error correction codes for correcting 4 error bits - Stack Overflow","meta_descriptions":[],"attrs_boilerpipe_text":"suppose you have corrupt string A=[ 1 0 1 1 1 0 1 0]; and original string B=[1 0 1 0 1 0 0 1]. step 1: check the parity of A and B: that are 1 and 0. step 2: parity is unmatched, so divide the string A and B by half and check the parity  in first half. if parity is matched on first half leave that half and take the 2nd half, where there must be unmatched parity. For our case first half parity has not matched now leave the 2nd half. Take the first half and again apply divide and conquer method until you end up with 1 bit. Now you detect the error bit. so flip the error bit in A (i.e correct). step 3: permute the bitstrings A and B with same permutation function so that error locations are changed. now do again from step 1.   repeat the procedure , until your desired error correction numbers.","attrs_markdown":"# ![site logo](https:\/\/stackoverflow.com\/Content\/Img\/SE-logo75.png)\nBy clicking “Sign up”, you agree to our [terms of service](https:\/\/stackoverflow.com\/legal\/terms-of-service\/public) and acknowledge you have read our [privacy policy](https:\/\/stackoverflow.com\/legal\/privacy-policy).\n\n# OR\n\nAlready have an account? [Log in](https:\/\/stackoverflow.com\/users\/login)\n\n[Skip to main content](https:\/\/stackoverflow.com\/questions\/26256488\/error-correction-codes-for-correcting-4-error-bits#content)\n\n[Stack Overflow](https:\/\/stackoverflow.com\/)\n\n1. 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[What's reputation and how do I get it?](https:\/\/stackoverflow.com\/help\/whats-reputation)\n\nInstead, you can save this post to reference later.\n\nSave this post for later\n\nNot now\n\n# ![Illustration of upvote icon after it is clicked](https:\/\/cdn.sstatic.net\/Img\/modal\/img-free-votes.png?v=1c5aa3dac50b)\n# Thanks for your vote!   You now have 5 free votes weekly.\nFree votes\n\n- count toward the total vote score\n- does not give reputation to the author\n\nContinue to help good content that is interesting, well-researched, and useful, rise to the top! To gain full voting privileges, [earn reputation](https:\/\/stackoverflow.com\/help\/whats-reputation).\n\nGot it\\!\n\nGo to help center to learn more\n\n# [Error correction codes for correcting 4 error bits](https:\/\/stackoverflow.com\/questions\/26256488\/error-correction-codes-for-correcting-4-error-bits)\n[Ask Question](https:\/\/stackoverflow.com\/questions\/ask)\n\nAsked\n\n11 years ago\n\nModified [11 years ago](https:\/\/stackoverflow.com\/questions\/26256488\/error-correction-codes-for-correcting-4-error-bits?lastactivity \"2014-10-08 14:38:11Z\")\n\nViewed 625 times\n\nThis question shows research effort; it is useful and clear\n\n0\n\nSave this question.\n\nShow activity on this post.\n\nI have a string message \"Man\" where each character is encoded to 8 bits. Therefore, a total of 24 bits will be transmitted.\n\nI am very interested to know what are the error correction codes that are not able to correct more than 4 error bits. More specifically, is there any error correction that can correct at most 4 errors ?\n\nAny help will be very appreciated.\n\n- [error-correction](https:\/\/stackoverflow.com\/questions\/tagged\/error-correction \"show questions tagged 'error-correction'\")\n\n[Share](https:\/\/stackoverflow.com\/q\/26256488 \"Short permalink to this question\")\n\nShare a link to this question\n\nCopy link\n\n[CC BY-SA 3.0](https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/ \"The current license for this post: CC BY-SA 3.0\")\n\n[Improve this question](https:\/\/stackoverflow.com\/posts\/26256488\/edit)\n\nFollow\n\nFollow this question to receive notifications\n\n[edited Oct 8, 2014 at 14:38](https:\/\/stackoverflow.com\/posts\/26256488\/revisions \"show all edits to this post\")\n\nChristina[Christina](https:\/\/stackoverflow.com\/users\/2976116\/christina)\n\nasked Oct 8, 2014 at 12:05\n\n[![Christina's user avatar](https:\/\/www.gravatar.com\/avatar\/222ad830e5a888763bdb830b81f51391?s=64&d=identicon&r=PG&f=y&so-version=2)](https:\/\/stackoverflow.com\/users\/2976116\/christina)\n\n[Christina](https:\/\/stackoverflow.com\/users\/2976116\/christina)Christina\n\n9351717 silver badges4343 bronze badges\n\n3\n\n- one easy way of error correction is BINARY Search method by checking parities.why you want to correct only 4 errors?\n  \n  Hum\n  \n  – [Hum](https:\/\/stackoverflow.com\/users\/3744763\/hum \"484 reputation\")\n  \n  2014-10-08 12:12:23 +00:00\n  \n  [Commented Oct 8, 2014 at 12:12](https:\/\/stackoverflow.com\/questions\/26256488\/error-correction-codes-for-correcting-4-error-bits#comment107194198_26256488)\n- Yes I am interested to use a non efficient error correction. Do you know any code that can correct only 4 bits ?\n  \n  Christina\n  \n  – [Christina](https:\/\/stackoverflow.com\/users\/2976116\/christina \"935 reputation\")\n  \n  2014-10-08 12:13:41 +00:00\n  \n  [Commented Oct 8, 2014 at 12:13](https:\/\/stackoverflow.com\/questions\/26256488\/error-correction-codes-for-correcting-4-error-bits#comment107194199_26256488)\n- 1\n  Why is this tagged `image-processing`?\n  \n  Unapiedra\n  \n  – [Unapiedra](https:\/\/stackoverflow.com\/users\/461597\/unapiedra \"16,468 reputation\")\n  \n  2014-10-08 14:29:09 +00:00\n  \n  [Commented Oct 8, 2014 at 14:29](https:\/\/stackoverflow.com\/questions\/26256488\/error-correction-codes-for-correcting-4-error-bits#comment41193954_26256488)\n\n[Add a comment](https:\/\/stackoverflow.com\/questions\/26256488\/error-correction-codes-for-correcting-4-error-bits \"Use comments to ask for more information or suggest improvements. Avoid answering questions in comments.\")   \\|\n\n## 1 Answer 1\nSorted by:\n\n[Reset to default](https:\/\/stackoverflow.com\/questions\/26256488\/error-correction-codes-for-correcting-4-error-bits?answertab=scoredesc#tab-top)\n\nThis answer is useful\n\n1\n\nSave this answer.\n\nShow activity on this post.\n\nsuppose you have corrupt string A=\\[ 1 0 1 1 1 0 1 0\\]; and original string B=\\[1 0 1 0 1 0 0 1\\].\n\nstep 1: check the parity of A and B: that are 1 and 0.\n\nstep 2: parity is unmatched, so divide the string A and B by half and check the parity in first half. if parity is matched on first half leave that half and take the 2nd half, where there must be unmatched parity. For our case first half parity has not matched now leave the 2nd half. Take the first half and again apply divide and conquer method until you end up with 1 bit. Now you detect the error bit. so flip the error bit in A (i.e correct).\n\nstep 3: permute the bitstrings A and B with same permutation function so that error locations are changed. now do again from step 1.\n\nrepeat the procedure , until your desired error correction numbers.\n\n[Share](https:\/\/stackoverflow.com\/a\/26256846 \"Short permalink to this answer\")\n\nShare a link to this answer\n\nCopy link\n\n[CC BY-SA 3.0](https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/ \"The current license for this post: CC BY-SA 3.0\")\n\n[Improve this answer](https:\/\/stackoverflow.com\/posts\/26256846\/edit)\n\nFollow\n\nFollow this answer to receive notifications\n\nanswered Oct 8, 2014 at 12:24\n\n[![Hum's user avatar](https:\/\/www.gravatar.com\/avatar\/5e5a597e3be0e6d0f9b4601b6335bfc7?s=64&d=identicon&r=PG&f=y&so-version=2)](https:\/\/stackoverflow.com\/users\/3744763\/hum)\n\n[Hum](https:\/\/stackoverflow.com\/users\/3744763\/hum)Hum\n\n48422 gold badges66 silver badges1111 bronze badges\n\nSign up to request clarification or add additional context in comments.\n\n## 3 Comments\nAdd a comment\n\n[![](https:\/\/www.gravatar.com\/avatar\/222ad830e5a888763bdb830b81f51391?s=48&d=identicon&r=PG&f=y&so-version=2)](https:\/\/stackoverflow.com\/users\/2976116\/christina)\n\nChristina\n\n[Christina](https:\/\/stackoverflow.com\/users\/2976116\/christina)\n\n[Over a year ago](https:\/\/stackoverflow.com\/questions\/26256488\/error-correction-codes-for-correcting-4-error-bits#comment41189337_26256846)\n\nWhat is the name of this error correction code? are you sure about this explanation ?\n\n2014-10-08T12:29:24.153Z+00:00\n\n0\n\nReply\n\n- Copy link\n\n[![](https:\/\/www.gravatar.com\/avatar\/5e5a597e3be0e6d0f9b4601b6335bfc7?s=48&d=identicon&r=PG&f=y&so-version=2)](https:\/\/stackoverflow.com\/users\/3744763\/hum)\n\nHum\n\n[Hum](https:\/\/stackoverflow.com\/users\/3744763\/hum)\n\n[Over a year ago](https:\/\/stackoverflow.com\/questions\/26256488\/error-correction-codes-for-correcting-4-error-bits#comment41189416_26256846)\n\nthis is the good way to do, try this. it works, you can correct more than 20% erros if you want.\n\n2014-10-08T12:31:54.993Z+00:00\n\n0\n\nReply\n\n- Copy link\n\n[![](https:\/\/www.gravatar.com\/avatar\/222ad830e5a888763bdb830b81f51391?s=48&d=identicon&r=PG&f=y&so-version=2)](https:\/\/stackoverflow.com\/users\/2976116\/christina)\n\nChristina\n\n[Christina](https:\/\/stackoverflow.com\/users\/2976116\/christina)\n\n[Over a year ago](https:\/\/stackoverflow.com\/questions\/26256488\/error-correction-codes-for-correcting-4-error-bits#comment41191475_26256846)\n\nThank you, really it is a very interesting method\n\n2014-10-08T13:28:10.58Z+00:00\n\n0\n\nReply\n\n- Copy link\n\nAdd a comment\n\nStart asking to get answers\n\nFind the answer to your question by asking.\n\n[Ask question](https:\/\/stackoverflow.com\/questions\/ask)\n\nExplore related 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Boilerpipe Text	suppose you have corrupt string A=[ 1 0 1 1 1 0 1 0]; and original string B=[1 0 1 0 1 0 0 1]. step 1: check the parity of A and B: that are 1 and 0. step 2: parity is unmatched, so divide the string A and B by half and check the parity in first half. if parity is matched on first half leave that half and take the 2nd half, where there must be unmatched parity. For our case first half parity has not matched now leave the 2nd half. Take the first half and again apply divide and conquer method until you end up with 1 bit. Now you detect the error bit. so flip the error bit in A (i.e correct). step 3: permute the bitstrings A and B with same permutation function so that error locations are changed. now do again from step 1. repeat the procedure , until your desired error correction numbers.
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To gain full voting privileges, [earn reputation](https://stackoverflow.com/help/whats-reputation). Got it\! Go to help center to learn more # [Error correction codes for correcting 4 error bits](https://stackoverflow.com/questions/26256488/error-correction-codes-for-correcting-4-error-bits) [Ask Question](https://stackoverflow.com/questions/ask) Asked 11 years ago Modified [11 years ago](https://stackoverflow.com/questions/26256488/error-correction-codes-for-correcting-4-error-bits?lastactivity "2014-10-08 14:38:11Z") Viewed 625 times This question shows research effort; it is useful and clear 0 Save this question. Show activity on this post. I have a string message "Man" where each character is encoded to 8 bits. Therefore, a total of 24 bits will be transmitted. I am very interested to know what are the error correction codes that are not able to correct more than 4 error bits. More specifically, is there any error correction that can correct at most 4 errors ? Any help will be very appreciated. - [error-correction](https://stackoverflow.com/questions/tagged/error-correction "show questions tagged 'error-correction'") [Share](https://stackoverflow.com/q/26256488 "Short permalink to this question") Share a link to this question Copy link [CC BY-SA 3.0](https://creativecommons.org/licenses/by-sa/3.0/ "The current license for this post: CC BY-SA 3.0") [Improve this question](https://stackoverflow.com/posts/26256488/edit) Follow Follow this question to receive notifications [edited Oct 8, 2014 at 14:38](https://stackoverflow.com/posts/26256488/revisions "show all edits to this post") Christina[Christina](https://stackoverflow.com/users/2976116/christina) asked Oct 8, 2014 at 12:05 [![Christina's user avatar](https://www.gravatar.com/avatar/222ad830e5a888763bdb830b81f51391?s=64&d=identicon&r=PG&f=y&so-version=2)](https://stackoverflow.com/users/2976116/christina) [Christina](https://stackoverflow.com/users/2976116/christina)Christina 9351717 silver badges4343 bronze badges 3 - one easy way of error correction is BINARY Search method by checking parities.why you want to correct only 4 errors? Hum – [Hum](https://stackoverflow.com/users/3744763/hum "484 reputation") 2014-10-08 12:12:23 +00:00 [Commented Oct 8, 2014 at 12:12](https://stackoverflow.com/questions/26256488/error-correction-codes-for-correcting-4-error-bits#comment107194198_26256488) - Yes I am interested to use a non efficient error correction. Do you know any code that can correct only 4 bits ? Christina – [Christina](https://stackoverflow.com/users/2976116/christina "935 reputation") 2014-10-08 12:13:41 +00:00 [Commented Oct 8, 2014 at 12:13](https://stackoverflow.com/questions/26256488/error-correction-codes-for-correcting-4-error-bits#comment107194199_26256488) - 1 Why is this tagged `image-processing`? Unapiedra – [Unapiedra](https://stackoverflow.com/users/461597/unapiedra "16,468 reputation") 2014-10-08 14:29:09 +00:00 [Commented Oct 8, 2014 at 14:29](https://stackoverflow.com/questions/26256488/error-correction-codes-for-correcting-4-error-bits#comment41193954_26256488) [Add a comment](https://stackoverflow.com/questions/26256488/error-correction-codes-for-correcting-4-error-bits "Use comments to ask for more information or suggest improvements. Avoid answering questions in comments.") \\| ## 1 Answer 1 Sorted by: [Reset to default](https://stackoverflow.com/questions/26256488/error-correction-codes-for-correcting-4-error-bits?answertab=scoredesc#tab-top) This answer is useful 1 Save this answer. Show activity on this post. suppose you have corrupt string A=\[ 1 0 1 1 1 0 1 0\]; and original string B=\[1 0 1 0 1 0 0 1\]. step 1: check the parity of A and B: that are 1 and 0. step 2: parity is unmatched, so divide the string A and B by half and check the parity in first half. if parity is matched on first half leave that half and take the 2nd half, where there must be unmatched parity. For our case first half parity has not matched now leave the 2nd half. Take the first half and again apply divide and conquer method until you end up with 1 bit. Now you detect the error bit. so flip the error bit in A (i.e correct). step 3: permute the bitstrings A and B with same permutation function so that error locations are changed. now do again from step 1. repeat the procedure , until your desired error correction numbers. [Share](https://stackoverflow.com/a/26256846 "Short permalink to this answer") Share a link to this answer Copy link [CC BY-SA 3.0](https://creativecommons.org/licenses/by-sa/3.0/ "The current license for this post: CC BY-SA 3.0") [Improve this answer](https://stackoverflow.com/posts/26256846/edit) Follow Follow this answer to receive notifications answered Oct 8, 2014 at 12:24 [![Hum's user avatar](https://www.gravatar.com/avatar/5e5a597e3be0e6d0f9b4601b6335bfc7?s=64&d=identicon&r=PG&f=y&so-version=2)](https://stackoverflow.com/users/3744763/hum) [Hum](https://stackoverflow.com/users/3744763/hum)Hum 48422 gold badges66 silver badges1111 bronze badges Sign up to request clarification or add additional context in comments. ## 3 Comments Add a comment [![](https://www.gravatar.com/avatar/222ad830e5a888763bdb830b81f51391?s=48&d=identicon&r=PG&f=y&so-version=2)](https://stackoverflow.com/users/2976116/christina) Christina [Christina](https://stackoverflow.com/users/2976116/christina) [Over a year ago](https://stackoverflow.com/questions/26256488/error-correction-codes-for-correcting-4-error-bits#comment41189337_26256846) What is the name of this error correction code? are you sure about this explanation ? 2014-10-08T12:29:24.153Z+00:00 0 Reply - Copy link [![](https://www.gravatar.com/avatar/5e5a597e3be0e6d0f9b4601b6335bfc7?s=48&d=identicon&r=PG&f=y&so-version=2)](https://stackoverflow.com/users/3744763/hum) Hum [Hum](https://stackoverflow.com/users/3744763/hum) [Over a year ago](https://stackoverflow.com/questions/26256488/error-correction-codes-for-correcting-4-error-bits#comment41189416_26256846) this is the good way to do, try this. it works, you can correct more than 20% erros if you want. 2014-10-08T12:31:54.993Z+00:00 0 Reply - Copy link [![](https://www.gravatar.com/avatar/222ad830e5a888763bdb830b81f51391?s=48&d=identicon&r=PG&f=y&so-version=2)](https://stackoverflow.com/users/2976116/christina) Christina [Christina](https://stackoverflow.com/users/2976116/christina) [Over a year ago](https://stackoverflow.com/questions/26256488/error-correction-codes-for-correcting-4-error-bits#comment41191475_26256846) Thank you, really it is a very interesting method 2014-10-08T13:28:10.58Z+00:00 0 Reply - Copy link Add a comment Start asking to get answers Find the answer to your question by asking. 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