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https://issues.apache.org/jira/browse/SPARK-22201?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16192834#comment-16192834
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cold gin commented on SPARK-22201:
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Yes, it is only the default behavior that I think should be reversed; I don't
have a problem at all with supporting the stats for strings. If you look the
*default* output of the describe() api, it produces several fields (count,
mean, stddev, etc) - BY DEFAULT. For all of those output attributes to be
populated *by default* it include only numeric columns. This simple evidence of
what the default output produces is my argument for what should be included as
default input. It is also exactly the reason that the other person in
SPARK-16468 sighted the behavior as confusing. Supporting string columns imo is
fine, but should be controlled with an includeColTypes parameter, and not
included by default.
> 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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