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https://issues.apache.org/jira/browse/SPARK-22201?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16192231#comment-16192231
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Sean Owen commented on SPARK-22201:
-----------------------------------
If you're saying that string-valued columns should never appear in the output:
not sure I agree there's a problem. pandas will also output stats for such
columns, for example, and simply leave mean/stdev blank or NaN. The behavior
exists now, so would have to be a good reason that it's not allowed at all.
If you're just saying it shouldn't be there by default, again not sure that's
the least surprising thing. The API lets you choose a subset of columns. The
natural default with no args is to show all cols.
pandas seems to have an argument that controls whether to show string cols or
not. That's possible here too but so is simply selecting the columns of
interest.
> Dataframe describe includes string columns
> ------------------------------------------
>
> Key: SPARK-22201
> URL: https://issues.apache.org/jira/browse/SPARK-22201
> Project: Spark
> Issue Type: Bug
> Components: Spark Core
> Affects Versions: 2.2.0
> Reporter: cold gin
>
> As per the api documentation, the default no-arg Dataframe describe()
> function should only include numerical column types, but it is including
> String types as well. This creates unusable statistical results (for example,
> max returns "V8903" for one of the string columns in my dataset), and this
> also leads to stacktraces when you run show() on the resulting dataframe
> returned from describe().
> There also appears to be several related issues to this:
> https://issues.apache.org/jira/browse/SPARK-16468
> https://issues.apache.org/jira/browse/SPARK-16429
> But SPARK-16429 does not make sense with what the default api says, and only
> Int, Double, etc (numeric) columns should be included when generating the
> statistics.
> Perhaps this reveals the need for a new function to produce stats that make
> sense only for string columns, or else an additional parameter to describe()
> to filter in/out certain column types?
> In summary, the *default* describe api behavior (no arg behavior) should not
> include string columns. Note that boolean columns are correctly excluded by
> describe()
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