Using regex to find and delete data - python-3.x

Question

Need to search through data and delete customer Social Security Numbers.
with open('customerdata.csv') as csvfile:
reader = csv.DictReader(csvfile)
for row in reader:
data.append(row)
for row in customerdata.csv:
results = re.search(r'\d{3}-\d{2}-\d{4}', row)
re.replace(results, "", row)
print(results)
New to scripting and not sure what it is I need to do to fix this.

Answer 1

This is not a job for a regex.
You are using a csv.DictReader, which is awesome. This means you have access to the column names in your csv file. What you should do is make a note of the column that contains the SSN, then write out the row without it. Something like this (not tested):
with open('customerdata.csv') as csvfile:
reader = csv.DictReader(csvfile)
for row in reader:
del row['SSN']
print(row)
If you need to keep the data but blank it out, then something like:
with open('customerdata.csv') as csvfile:
reader = csv.DictReader(csvfile)
for row in reader:
row['SSN'] = ''
print(row)
Hopefully you can take things from here; for example, rather than printing, you might want to use a csv dict writer. Depends on your use case. Though, do stick with csv operations and definitely avoid regexes here. Your data is in csv format. Think about the data as rows and columns, not as individual strings to be regexed upon. :)

Answer 2

I'm not seeing a replace function for re in the Python 3.6.5 docs.
I believe the function you would want to use is re.sub:
re.sub(pattern, repl, string, count=0, flags=0)
Return the string obtained by replacing the leftmost non-overlapping occurrences of pattern in string by the replacement repl. If the pattern isn’t found, string is returned unchanged.
This means that all you need in your second for loop is:
for row in customerdata.csv:
results = re.sub(r'\d{3}-\d{2}-\d{4}', row, '')
print(results)