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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 edited comment on SPARK-22201 at 10/5/17 1:24 PM:
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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
output of the describe() no-args api, it produces several fields (count, mean,
stddev, etc) - by default. For all of those output attributes to be populated
by default you must include only numeric columns. This simple evidence of what
the default output produces is my argument for what should be included as the
default input. Supporting string columns is fine, but should be controlled with
an includeColTypes parameter, and not included by default imo.
was (Author: cold-gin):
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
output of the describe() no-args api, it produces several fields (count, mean,
stddev, etc) - by default. For all of those output attributes to be populated
by default you must include only numeric columns. This simple evidence of what
the default output produces is my argument for what should be included as the
default input. 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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