如何从pyspark.sql.function中提取值? [英] How to extract value from pyspark.sql.function?

问题描述

我正在使用一些pyspark.sql.functions

I'm using some pyspark.sql.functions:

print(ratings.select(mean('rating')).take(1))
print(ratings.select(stddev('rating')).take(1))

输出为:

[Row(avg(rating)=3.581564453029317)]
[Row(stddev_samp(rating,0,0)=1.1171018453732544)]

如何提取值，以便可以将其分配给变量，例如

How can I extract the value so that I can assign it to a variable, e.g.

mean_ratings = ratings.select(mean('rating'))

推荐答案

Take返回行列表.索引到列表中以获取第一行，然后拉出您要查找的字段:

Take returns a list of Rows. Index into the list to get the first row, then pull out the field you are looking for:

mean_ratings = ratings.select(mean('rating')).take(1)[0]['avg(rating)']

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