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POWhat makes these two R data frames not identical?
 

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  1. POWhat makes these two R data frames not identical?
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    <p>I have two small data frames, <code>this_tx</code> and <code>last_tx</code>. They are, in every way that I can tell, completely identical. <code>this_tx</code> == <code>last_tx</code> results in a frame of identical dimensions, all <code>TRUE</code>. <code>this_tx %in% last_tx</code>, two <code>TRUEs</code>. Inspected visually, clearly identical. But when I call</p> <p><code>identical(this_tx, last_tx)</code></p> <p>I get a <code>FALSE</code>. Hilariously, even</p> <p><code>identical(str(this_tx), str(last_tx))</code></p> <p>will return a <code>TRUE</code>. If I set <code>this_tx &lt;- last_tx</code>, I'll get a <code>TRUE</code>.</p> <p>What is going on? I don't have the deepest understanding of R's internal mechanics, but I can't find a single difference between the two data frames. If it's relevant, the two variables in the frames are both factors - same levels, same numeric coding for the levels, both just subsets of the same original data frame. Converting them to character vectors doesn't help.</p> <p>Background (because I wouldn't mind help on this, either): I have records of drug treatments given to patients. Each treatment record essentially specifies a person and a date. A second table has a record for each drug and dose given during a particular treatment (usually, a few drugs are given each treatment). I'm trying to identify contiguous periods during which the person was taking the same combinations of drugs at the same doses.</p> <p>The best plan I've come up with is to check the treatments chronologically. If the combination of drugs and doses for treatment[i] is identical to the combination at treatment[i-1], then treatment[i] is a part of the same phase as treatment[i-1]. Of course, if I can't compare drug/dose combinations, that's right out.</p>
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    1. This table or related slice is empty.
    1. PTQuestion
    1. This table or related slice is empty.
    1. USMatt Parker
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    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
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      1. POWhat makes these two R data frames not identical?
      1. This table or related slice is empty.
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      1. POWhat makes these two R data frames not identical?
      1. This table or related slice is empty.
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      1. POWhat makes these two R data frames not identical?
      1. USTal Galili
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    1. COIf you could post an example pair of data frames it would help- preferably as the result of running `dput()` on the frames.
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      1. POWhat makes these two R data frames not identical?
      1. USSharpie
    2. COSharpie wins. The two data frames were still carrying the row.names of the mother data frame, which shows up in a dput() but not str(). Sharpie, if you post as an answer, I'll mark it best.
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      1. POWhat makes these two R data frames not identical?
      1. USMatt Parker
    3. COI'm actually surprised- I always thought `str` was a "prettified" version of `dput`. Guess it turns out that it is just a summary.
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      1. POWhat makes these two R data frames not identical?
      1. USSharpie
 

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