["python","pandas","dataframe","constructor","valueerror"]
Constructing DataFrame from values in variables yields "ValueError: If using all scalar values, you must pass an index"

I have two variables as follows. a = 2 b = 3 I want to construct a DataFrame from this: df2 = pd.DataFrame({'A':a, 'B':b}) This generates an error: ValueError: If using all scalar values, you must pass an index I tried this also: df2 = (pd.DataFrame({'a':a, 'b':b})).reset_index() This gives the same error message. How do I do what I want?
The error message says that if you're passing scalar values, you have to pass an index. So you can either not use scalar values for the columns -- e.g. use a list: >>> df = pd.DataFrame({'A': [a], 'B': [b]}) >>> df A B 0 2 3 or use scalar values and pass an index: >>> df = pd.DataFrame({'A': a, 'B': b}, index=[0, 3]) >>> df A B 0 2 3 3 2 3