如何将嵌套列添加到 DataFrame
问题描述：
我有一个数据框 df 具有以下架构:
I have a dataframe df with the following schema:
root
|-- city_name: string (nullable = true)
|-- person: struct (nullable = true)
| |-- age: long (nullable = true)
| |-- name: string (nullable = true)
我想要做的是在我的 person 结构中添加一个嵌套列，比如 car_brand.我该怎么做?
What I want to do is add a nested column, say car_brand to my person structure. How would I do it?
预期的最终架构如下所示:
The expected final schema would look like this:
root
|-- city_name: string (nullable = true)
|-- person: struct (nullable = true)
| |-- age: long (nullable = true)
| |-- name: string (nullable = true)
| |-- car_brand: string (nullable = true)
答
您可以解压结构体并将其添加到新结构体中，同时包括新列.例如，将bmw"添加到数据框中的所有人中，如下所示:
You can unpack the struct and add it to a new one, including the new column at the same time. For example, adding "bmw" to all persons in the dataframe be done like this:
df.withColumn("person", struct($"person.*", lit("bmw").as("car_brand")))