I am trying to read a 3 column csv into a dictionary with the code below. The 1st column is the unique identifier, and the following 2 are information related.
d = dict()
with open('filemane.csv', 'r') as infile:
reader = csv.reader(infile)
mydict = dict((rows[0:3]) for rows in reader)
print mydict
When I run this code I get this error:
Traceback (most recent call last):
File "commissionsecurity.py", line 34, in <module>
mydict = dict((rows[0:3]) for rows in reader)
ValueError: dictionary update sequence element #0 has length 3; 2 is required
Dictionaries need to get a key along with a value. When you have
mydict = dict((rows[0:3]) for rows in reader)
^^^^^^^^^
ambiguous
You are passing in a list that is of length 3 which is not of the length 2 (key, value)
format that is expected. The error message hints at this by saying that the length required is 2 and not the 3 that was provided. To fix this make the key be rows[0]
and the associated value be rows[1:3]
:
mydict = dict((rows[0], rows[1:3]) for rows in reader)
^^^^^^ ^^^^^^^^^
key value
You can do something along the lines of:
with open('filemane.csv', 'r') as infile:
reader = csv.reader(infield)
d={row[0]:row[1:] for row in reader}
Or,
d=dict()
with open('filemane.csv', 'r') as infile:
reader = csv.reader(infield)
for row in reader:
d[row[0]]=row[1:]
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