CODEWITHSUNDEEP
pythonpandasexception
Iwan
Iwan

Reputation: 319

Try and except statements, Python

It seems like a simple question but I can't figure it out from googling and reading through Stackoverflow.

My question is how can I use a try statement on a variable and append it to a list?

In the sample below, I'm trying to obtain index labels using pandas from a list of files. I want to convert each one into a variable, append them all into a list and concatenate them. However I'm struggling to understand how I can try "parsed_file.loc["Staff" : "Total Staff"].copy()", and convert it into a variable to be appended to a list.

I sort of understand that in the example below I'm trying to use a local scope variable in global scope which would throw a NameError. I could use a function and return the variable within the function, but I then get a 'TypeError: cannot concatenate a non-NDFrame object'. I tried to convert the variable into a DataFrame in the function but it returns the same error.

Not all files will have the index label, therefore I'm using the except: KeyError to skip those files, and print the file location.

for file_ in allFiles:
        parsed_file = read_workbook(file_)
        parsed_file['filename'] = os.path.basename(file_)
        parsed_file.set_index(0, inplace = True)
        parsed_file.index.str.strip()

        try: Staff_ = parsed_file.loc["Staff" : "Total Staff"].copy()
        except KeyError: 
            print(file_)

        list_.append(Staff_)
frame = pd.concat(list_)

Upvotes: 0

Views: 6409

Answers (1)

StefanE
StefanE

Reputation: 7630

Everything inside an try block will execute line by line and if an exception occures it will stop execution and jump to the except block. So I have changed your code a bit and if there is an exception on the line where you execute Staff_ = parsed_file.loc["Staff" : "Total Staff"].copy() it wont execute the rest of the lines within the try block. Documentation here describes try Python Try Catch

for file_ in allFiles:
        parsed_file = read_workbook(file_)
        parsed_file['filename'] = os.path.basename(file_)
        parsed_file.set_index(0, inplace = True)
        parsed_file.index.str.strip()

        try: 
            Staff_ = parsed_file.loc["Staff" : "Total Staff"].copy()
            # Line below won't be executed in case of an exception
            list_.append(Staff_)
        except KeyError: 
            print(file_)

frame = pd.concat(list_)

Upvotes: 1

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