Write to csv and I get error : _csv.Error: sequence expected

Question

Please help. I get an error when I want to write my dict AllListInstance to csv file. This is my code:

AllListInstance= {frozenset(['OFFENSE INVOLVING CHILDREN']): [(95,), (96,), (35,), (80,), (100,)], frozenset(['BATTERY', 'THEFT']): [(173, 209), (173, 224)]}

with open('test1.csv', 'wb') as csv_file:
   for key in AllListInstance.keys():
    csv_writer = csv.writer(csv_file)
    csv_writer.writerow(len(AllListInstance[key]))
    for y in range(len(key)):
        csv_writer.writerow([x[y] for x in key])
        csv_writer.writerow(x[y] for x in AllListInstance[key])

output expected:

5   # len(AllListInstance["OFFENSE INVOLVING CHILDREN"]) count of member
OFFENSE INVOLVING CHILDREN
95
96
35
80
100
2 # len(AllListInstance['BATTERY','THIEF']) count of member
BATTERY        THIEF
173            209
173            224

Error:

    csv_writer.writerow(len(AllListInstance[key]))
_csv.Error: sequence expected

Solusion for my expected ouput:

with open('test8.csv', 'wb') as csv_file:
  for key in AllListInstance.keys():
    csv_writer = csv.writer(csv_file)
    csv_writer.writerow([len(key),len(AllListInstance[key])])
    csv_writer.writerow(list(key))
    for x in AllListInstance[key]:
        csv_writer.writerow(list(x))

Martijn Pieters · Accepted Answer · 2016-01-16 00:48:48Z

1

You are passing in a single integer:

len(AllListInstance[key])

That's not a sequence, which is what csv_writer.writerow() expects. If you want to write one column with the length value, wrap that in a list:

csv_writer.writerow([len(AllListInstance[key])])

answered Jan 16, 2016 at 0:48

Martijn Pieters

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6 Comments

Erna Piantari Over a year ago

next error comes : csv_writer.writerow(x[y] for x in key) _csv.Error: sequence expected

Martijn Pieters Over a year ago

@ErnaPiantari: again, add [...] brackets; a generator expression isn't supported, the result of a list comprehension is.

Erna Piantari Over a year ago

for csv_writer.writerow([x[y] for x in key]) my expected output is print string OFFENSE INVOLVING CHILDREN, But using my code , the output is only the first character O. Can you give me suggestion?

Martijn Pieters Over a year ago

Why not just use csv_writer.writerow(key) instead? No need to loop there. You can write the value for each key with csv_writer.writerows(AllListInstance[key]).

Erna Piantari Over a year ago

AllListInstance.values() is frozen set. When I print csv_writer.writerow(key) the output is frozenset(['BATTERY', 'THEFT']). I want to split become BATTERY and THEAF and print to different coloum.

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