如何降低数据框列名的大小写而不是其值? [英] How to lower the case of column names of a data frame but not its values?

问题描述

如何降低数据框列名的大小写而不是其值?使用 RAW Spark SQL 和 Dataframe 方法?

How to lower the case of column names of a data frame but not its values? using RAW Spark SQL and Dataframe methods ?

输入数据框(假设我有 100 个大写的这些列)

Input data frame (Imagine I have 100's of these columns in uppercase)

NAME | COUNTRY | SRC        | CITY       | DEBIT
---------------------------------------------
"foo"| "NZ"    | salary     | "Auckland" | 15.0
"bar"| "Aus"   | investment | "Melbourne"| 12.5

目标数据框

name | country | src        | city       | debit
------------------------------------------------
"foo"| "NZ"    | salary     | "Auckland" | 15.0
"bar"| "Aus"   | investment | "Melbourne"| 12.5

推荐答案

Java 8 将列名转换为小写的解决方案.

Java 8 solution to convert the column names to lower case.

import static org.apache.spark.sql.functions.col;
import org.apache.spark.sql.Column;

df.select(Arrays.asList(df.columns()).stream().map(x -> col(x).as(x.toLowerCase())).toArray(size -> new Column[size])).show(false);

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