Avoid accessing wrong column in csv
I was parsing few csv files. All were from same provider. Format is
Date, Name, Email, Company, City etc in one file. I made an assumption all the downloaded files are in the same format. For my surprise few files had same format and others din’t.
with open(filename, 'rb') as f: reader = csv.reader(f) reader.next() # first row contains column names for row in reader: name, email, company = row, row, row #save to db
In the above code the fundamental mistake is fixing the position of the columns in csv file. What happens if
company position is interchanged? In simple
How can I avoid these situations ?
with open(filename, 'rb') as f: reader = csv.reader(f) header = reader.next() #reader is not list name_pos, email_pos, company_pos = header.index("Name"),header.index("Email"),header.index("Company") with open(filename, 'rb') as f: reader = csv.reader(f) reader.next() for row in reader: name, email, company = row[name_pos], row[email_pos], row[company_pos] #save to db
The code is bit longer here, but robost. The above snippet doesn’t rely on column position but only relies on column name in the first line. Ofcourse
header.index will raise
ValueError you can wrap the exception. First all the required column positions are retrieved, file is reopened, first row is omitted and other details are accessed.
- Five reasons to use Py.test
- Build Plugins with Pluggy
- Render local images in datasette using datasette-render-local-images
- Parameterize Python Tests
- “Don’t touch your face” - Neural Network will warn you
This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.