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Col names not detected – AnalysisException: Cannot resolve ‘Name’ given input columns ‘col10’

x89

I’m trying to run a transformation function in a pyspark script:

datasource0 = glueContext.create_dynamic_frame.from_catalog(database = "dev", table_name = "test_csv", transformation_ctx = "datasource0")
...
dataframe = datasource0.toDF()
...
def to_long(df, by):

    # Filter dtypes and split into column names and type description
    cols, dtypes = zip(*((c, t) for (c, t) in df.dtypes if c not in by))
    # Spark SQL supports only homogeneous columns
    assert len(set(dtypes)) == 1, "All columns have to be of the same type"

    # Create and explode an array of (column_name, column_value) structs
    kvs = explode(array([
      struct(lit(c).alias("key"), col(c).alias("val")) for c in cols
    ])).alias("kvs")

    return df.select(by + [kvs]).select(by + ["kvs.key", "kvs.val"])

#to_long(df, ["A"])
....
df = to_long(dataframe, ["Name","Type"])

My dataset looks like this:

Name   |01/01(FRI)|01/02(SAT)|
ALZA CZ|      0   |         0
CLPA CZ|      1   |         5

My desired output is something like this:

Name   |Type        |    Date.    |Value    |
ALZA CZ|New         | 01/01(FRI)  |     0
CLPA CZ|New         | 01/01(FRI)  |     1
ALZA CZ|Old         | 01/02(SAT)  |     1
CLPA CZ|Old         | 01/02(SAT)  |     5

However, the last code line gives me an error similar to this:

AnalysisException: Cannot resolve 'Name' given input columns 'col10'

When I check:

df.show()

I see ‘col1’, ‘col2’ etc in the first row instead of the actual labels ( [“Name”,”Type”] ). Should I separately remove and then add the original column titles?

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Answer

It seems like that your meta data table was configured using the built-in CSV classifier. If this classifier isn’t able to detect a header, it will call the columns col1, col2 etc.

Your problem lies one stage before your ETL job, so in my opinion you shouldn’t remove and re-add the original column titles, but fix your data import / schema detection, by using a custom classifier.

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