Writing with Python's built-in .csv module

Question

[Please note that this is a different question from the already answered How to replace a column using Python’s built-in .csv writer module?]

I need to do a find and rep

Answer 1

You cannot read and write the same file.

source = open("PALTemplateData.csv","rb")
reader = csv.reader(source , dialect)

target = open("AnotherFile.csv","wb")
writer = csv.writer(target , dialect)

The normal approach to ALL file manipulation is to create a modified COPY of the original file. Don't try to update files in place. It's just a bad plan.

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Edit

In the lines

source = open("PALTemplateData.csv","rb")

target = open("AnotherFile.csv","wb")

The "rb" and "wb" are absolutely required. Every time you ignore those, you open the file for reading in the wrong format.

You must use "rb" to read a .CSV file. There is no choice with Python 2.x. With Python 3.x, you can omit this, but use "r" explicitly to make it clear.

You must use "wb" to write a .CSV file. There is no choice with Python 2.x. With Python 3.x, you must use "w".

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Edit

It appears you are using Python3. You'll need to drop the "b" from "rb" and "wb".

Read this: http://docs.python.org/3.0/library/functions.html#open