从特定列Scala Spark数据帧中获取最小值和最大值 [英] get min and max from a specific column scala spark dataframe

问题描述

我想从数据框中访问特定列的最小值和最大值，但是我没有列的标题，只有列号，所以我应该使用scala吗?

I would like to access to the min and max of a specific column from my dataframe but I don't have the header of the column, just its number, so I should I do using scala ?

也许是这样的:

val q = nextInt(ncol) //we pick a random value for a column number
col = df(q)
val minimum = col.min()

很抱歉，这听起来像是一个愚蠢的问题，但我找不到有关此问题的信息:/

Sorry if this sounds like a silly question but I couldn't find any info on SO about this question :/

推荐答案

如何从元数据中获取列名:

How about getting the column name from the metadata:

val selectedColumnName = df.columns(q) //pull the (q + 1)th column from the columns array
df.agg(min(selectedColumnName), max(selectedColumnName))

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