Hello,
I have been struggling a while trying to figure out how to modify a csv file
using the csv.DictWriter class. Let's suppose I have the following code:
import csv
outfile=open('template.csv','w') # This is a pre-existing file that
contains 3 variables (3 columns). The variables will (or will not) have a value
each.
x='new_value'
writing=csv.DictWriter(outfile,
fieldnames=['variable1','variable2','variable2'])
data={'variable1' : x} # What I intent to do here is to overwrite whatever
value exists for variable 1. There will always exist only one value per
variable.
writing.writerow(data)
I have several questions about how DictWriter works, and I am sorry if my
questions have a very obvious answer, which I am 'obviously' missing.
1. When I run the code above for the first time, the contents of the
pre-existing file disappear, if I run the script a second time, now I can see
the value of x.
2. The fieldnames don't appear in the csv file, only the values.
3. Is there a way to let the DictWriter know that the header of the csv file
corresponds to all the fieldnames? To avoid typing all the names.
As usual, thank you very much for your help.
Judith
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