How to transform from wide to long format in python

[buran]

I think you are overthinking/overcomplicating this problem.

Is it save to state that

• You want first 8 columns (i.e. A-H), then last 2 columns, then the 9th and 10th columns
  
• The column names for first 10 columns are the same as in the original file, the last 2 columns (former 9th and 10th) will have new header - AttributeName and AttributeValue
  

fname = 'VY6_Row1_report_url_detections_per_frame.csv'
# fname = 'VY6_Row2_report_url_detections_per_frame.csv'

df =  pd.read_csv(fname)
col_drop = len(df.columns) - 10
df['AttributeName'] = df[df.columns[8]]
df['AttributeValue'] = df[df.columns[9]]
df.drop(labels=df.columns[8:8+col_drop], axis=1, inplace=True)
df.to_csv('VY6_out.csv', index=False)

Do you need to use pandas? Using csv module would also do.