Pyspark from_unixtime (unix_timestamp) does not convert to timestamp

问题

I am using Pyspark with Python 2.7. I have a date column in string (with ms) and would like to convert to timestamp

This is what I have tried so far

df = df.withColumn('end_time', from_unixtime(unix_timestamp(df.end_time, '%Y-%M-%d %H:%m:%S.%f')) )

printSchema() shows end_time: string (nullable = true)

when I expended timestamp as the type of variable

回答1:

Try using from_utc_timestamp:

from pyspark.sql.functions import from_utc_timestamp

df = df.withColumn('end_time', from_utc_timestamp(df.end_time, 'PST'))

You'd need to specify a timezone for the function, in this case I chose PST

If this does not work please give us an example of a few rows showing df.end_time

回答2:

Create a sample dataframe with Time-stamp formatted as string:

import pyspark.sql.functions as F
df = spark.createDataFrame([('22-Jul-2018 04:21:18.792 UTC', ),('23-Jul-2018 04:21:25.888 UTC',)], ['TIME'])
df.show(2,False)
df.printSchema()

Output:

+----------------------------+
|TIME                        |
+----------------------------+
|22-Jul-2018 04:21:18.792 UTC|
|23-Jul-2018 04:21:25.888 UTC|
+----------------------------+
root
|-- TIME: string (nullable = true)

Converting string time-format (including milliseconds ) to unix_timestamp(double). Since unix_timestamp() function excludes milliseconds we need to add it using another simple hack to include milliseconds. Extracting milliseconds from string using substring method (start_position = -7, length_of_substring=3) and Adding milliseconds seperately to unix_timestamp. (Cast to substring to float for adding)

df1 = df.withColumn("unix_timestamp",F.unix_timestamp(df.TIME,'dd-MMM-yyyy HH:mm:ss.SSS z') + F.substring(df.TIME,-7,3).cast('float')/1000)

Converting unix_timestamp(double) to timestamp datatype in Spark.

df2 = df1.withColumn("TimestampType",F.to_timestamp(df1["unix_timestamp"]))
df2.show(n=2,truncate=False)

This will give you following output

+----------------------------+----------------+-----------------------+
|TIME                        |unix_timestamp  |TimestampType          |
+----------------------------+----------------+-----------------------+
|22-Jul-2018 04:21:18.792 UTC|1.532233278792E9|2018-07-22 04:21:18.792|
|23-Jul-2018 04:21:25.888 UTC|1.532319685888E9|2018-07-23 04:21:25.888|
+----------------------------+----------------+-----------------------+

Checking the Schema:

df2.printSchema()


root
 |-- TIME: string (nullable = true)
 |-- unix_timestamp: double (nullable = true)
 |-- TimestampType: timestamp (nullable = true)

回答3:

Following might help:-

from pyspark.sql import functions as F
df = df.withColumn("end_time", F.from_unixtime(F.col("end_time"), 'yyyy-MM-dd HH:mm:ss.SS').cast("timestamp"))

[Updated]

来源：https://stackoverflow.com/questions/54337991/pyspark-from-unixtime-unix-timestamp-does-not-convert-to-timestamp

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date

pyspark