在 Pyspark 中将列类型从字符串更改为日期 [英] Change column type from string to date in Pyspark

问题描述

我正在尝试将我的列类型从字符串更改为日期.我参考了以下答案:

I'm trying to change my column type from string to date. I have consulted answers from:

1. 如何更改列在 DataFrames 中从字符串类型到日期类型?
2. 为什么我从 date_format() 得到空结果PySpark 函数?

当我尝试应用链接 1 中的答案时，结果却为空，因此我参考了链接 2 中的答案，但我不明白这部分:

When I tried to apply answers from link 1, I got null result instead, so I referred to answer from link 2 but I don't understand this part:

output_format = ...  # Some SimpleDateFormat string

我想直接从评论中提问，但唉，我的声誉还不够.

I would like to ask directly from the comment but alas, my reputation is not enough.

推荐答案

希望对您有所帮助！

from pyspark.sql.functions import col, unix_timestamp, to_date

#sample data
df = sc.parallelize([['12-21-2006'],
                     ['05-30-2007'],
                     ['01-01-1984'],
                     ['12-24-2017']]).toDF(["date_in_strFormat"])
df.printSchema()

df = df.withColumn('date_in_dateFormat', 
                   to_date(unix_timestamp(col('date_in_strFormat'), 'MM-dd-yyyy').cast("timestamp")))
df.show()
df.printSchema()

输出为:

root
 |-- date_in_strFormat: string (nullable = true)

+-----------------+------------------+
|date_in_strFormat|date_in_dateFormat|
+-----------------+------------------+
|       12-21-2006|        2006-12-21|
|       05-30-2007|        2007-05-30|
|       01-01-1984|        1984-01-01|
|       12-24-2017|        2017-12-24|
+-----------------+------------------+

root
 |-- date_in_strFormat: string (nullable = true)
 |-- date_in_dateFormat: date (nullable = true)

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