Arnold Klein questions

• duplicate a single column with several names in Pandas
• Convert date from excel file to pandas
• Parse date time in nested Pandas data frame
• Find the common string in a subgroup in a list in Python
• Side-by-side boxplots with Pandas
• Flatten nested pandas dataframe
• send an image (as numpy array) 'requests.post'
• find rows with k-consecutive NaNs in Pandas
• random sampling with Pandas data frame disjoint groups
• Searching for all matches in texts with Pandas

Arnold Klein answers