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Tag: python

Pyspark: cast array with nested struct to string

I have pyspark dataframe with a column named Filters: “array>” I want to save my dataframe in csv file, for that i need to cast the array to string type. I tried to cast it: DF.Filters.tostring() and DF.Filters.cast(StringType()), but both solutions generate error message for each row in the columns Filters: org.apache.spark.sql.catalyst.expressions.UnsafeArrayData@56234c19 The code is as follows Sample JSON data:

How to verify SqlAlchemy engine object

I can declare engine object with the invalid username, password or address and get no exception or error: it prints likes it is a valid engine object: What would be a common way to verify (to check) if the engine object is valid or if it is “connectable” to db? Answer Question: How to verify if the engine object is

Register temp table in dataframe not working

Below is my script to use sql in dataframe with python: df.show(5) shows result below: then I register the dataframe to a temp table: and tried to run some sql query like below: It doesn’t produce expected result, instead: I also tried: and it gives me: So it seems the registerTempTable method only create the table schema and the table

How to perform a left join in SQLALchemy?

I have a SQL query which perfroms a series of left joins on a few tables: So far, I have: but I can’t figure out how to make the join a LEFT JOIN. Answer The isouter=True flag will produce a LEFT OUTER JOIN which is the same as a LEFT JOIN. With your code: Declarative example:

Pandas DENSE RANK

I’m dealing with pandas dataframe and have a frame like this: I want to make an equialent to DENSE_RANK () over (order by year) function. to make an additional column like this: How can it be done in pandas? Thanks! Answer Use pd.Series.rank with method=’dense’

‘unicode’ object has no attribute ‘utcoffset’

In my admin, I am getting errors for only one class, ‘unicode’ object has no attribute ‘utcoffset’. I have looked at a few other similar questions and have been unable to solve it. Any ideas on how to fix it? The traceback is below the class. Traceback: Answer The default value for your pub_date field is a string. It should

Add an autoincrementing ID column to an existing table with Sqlite

Using Sqlite, I want to add an auto-incrementing ID column to an existing table which had previously no ID: How to do it properly? I have this error: sqlite3.OperationalError: near “auto_increment”: syntax error Answer An SQLite table cannot modified in a significant manner using alter table once it has been created. One common popular suggestion is to create a new

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