{
  "id": 191768,
  "title": "Meaning of negative timestamps",
  "url": "/competitions/riiid-test-answer-prediction/discussion/191768",
  "author_name": "",
  "post_date": "2020-10-18T14:09:30.495838200Z",
  "votes": null,
  "comment_count": 3,
  "views": 0,
  "content": "<p>While exploring the <code>timestamp</code> column, I noticed a significant number of negative values. If I understand correctly, the feature <code>timestamp</code> represents when an activity was completed. Could anyone explain the meaning of negative values?</p>",
  "messages": [
    {
      "id": "1053020",
      "postDate": "10/18/2020 14:09:30",
      "content": "<p>While exploring the <code>timestamp</code> column, I noticed a significant number of negative values. If I understand correctly, the feature <code>timestamp</code> represents when an activity was completed. Could anyone explain the meaning of negative values?</p>",
      "rawMarkdown": "While exploring the `timestamp` column, I noticed a significant number of negative values. If I understand correctly, the feature `timestamp` represents when an activity was completed. Could anyone explain the meaning of negative values?",
      "votes": null
    },
    {
      "id": "1053027",
      "postDate": "10/18/2020 14:23:13",
      "content": "<p>There aren't any negative timestamps as far as I can tell. I suspect you have imported the timestamps as 32 bit integers. The largest timestamps are greater than what fits into a signed 32 integer and can show up as  negative numbers.</p>",
      "rawMarkdown": "There aren't any negative timestamps as far as I can tell. I suspect you have imported the timestamps as 32 bit integers. The largest timestamps are greater than what fits into a signed 32 integer and can show up as  negative numbers.",
      "votes": null
    },
    {
      "id": "1053046",
      "postDate": "10/18/2020 14:46:02",
      "content": "<p>Thanks, <a href=\"https://www.kaggle.com/christoffer\" target=\"_blank\">@christoffer</a>. </p>\n<p>Previously, I loaded the <code>timestamp</code> column in 'int32' datatype to avoid RAM overflow. I'm now using 'int64' datatype to load <code>timestamp</code> data and I'm able to avoid the negative values. However, I'm observing <code>timestamp</code> values as 0 now. </p>\n<p>Could you please explain the significance of 0 <code>timestamp</code> values? </p>",
      "rawMarkdown": "Thanks, @christoffer. \n\nPreviously, I loaded the `timestamp` column in 'int32' datatype to avoid RAM overflow. I'm now using 'int64' datatype to load `timestamp` data and I'm able to avoid the negative values. However, I'm observing `timestamp` values as 0 now. \n\nCould you please explain the significance of 0 `timestamp` values?",
      "votes": null
    },
    {
      "id": "1053056",
      "postDate": "10/18/2020 14:51:02",
      "content": "<p><code>0 timestamp</code> means that its the start time of that session by a user</p>",
      "rawMarkdown": "`0 timestamp` means that its the start time of that session by a user",
      "votes": null
    }
  ],
  "comments": [
    {
      "id": 1053027,
      "author_name": "christoffer",
      "author_url": "",
      "post_date": "10/18/2020 14:23:13",
      "content": "<p>There aren't any negative timestamps as far as I can tell. I suspect you have imported the timestamps as 32 bit integers. The largest timestamps are greater than what fits into a signed 32 integer and can show up as  negative numbers.</p>",
      "votes": null,
      "replies": [
        {
          "id": 1053046,
          "author_name": "ashuprasadgermany",
          "author_url": "",
          "post_date": "10/18/2020 14:46:02",
          "content": "<p>Thanks, <a href=\"https://www.kaggle.com/christoffer\" target=\"_blank\">@christoffer</a>. </p>\n<p>Previously, I loaded the <code>timestamp</code> column in 'int32' datatype to avoid RAM overflow. I'm now using 'int64' datatype to load <code>timestamp</code> data and I'm able to avoid the negative values. However, I'm observing <code>timestamp</code> values as 0 now. </p>\n<p>Could you please explain the significance of 0 <code>timestamp</code> values? </p>",
          "votes": null,
          "replies": []
        },
        {
          "id": 1053056,
          "author_name": "msharuk589",
          "author_url": "",
          "post_date": "10/18/2020 14:51:02",
          "content": "<p><code>0 timestamp</code> means that its the start time of that session by a user</p>",
          "votes": null,
          "replies": []
        }
      ]
    }
  ],
  "raw_markdown_by_id": {
    "1053020": "While exploring the `timestamp` column, I noticed a significant number of negative values. If I understand correctly, the feature `timestamp` represents when an activity was completed. Could anyone explain the meaning of negative values?",
    "1053027": "There aren't any negative timestamps as far as I can tell. I suspect you have imported the timestamps as 32 bit integers. The largest timestamps are greater than what fits into a signed 32 integer and can show up as  negative numbers.",
    "1053046": "Thanks, @christoffer. \n\nPreviously, I loaded the `timestamp` column in 'int32' datatype to avoid RAM overflow. I'm now using 'int64' datatype to load `timestamp` data and I'm able to avoid the negative values. However, I'm observing `timestamp` values as 0 now. \n\nCould you please explain the significance of 0 `timestamp` values?",
    "1053056": "`0 timestamp` means that its the start time of that session by a user"
  },
  "source": "meta"
}