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February 7, 2013 21:25
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Python: CSV reading in python
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# Use reader() to create a an object for reading data from a CSV file. The reader can be used as an iterator | |
# to process the rows of the file in order. For example: | |
import csv | |
import sys | |
f = open(sys.argv[1], 'rt') | |
try: | |
reader = csv.reader(f) | |
for row in reader: | |
print row | |
finally: | |
f.close() | |
# the original file: | |
"Title 1","Title 2","Title 3" | |
1,"a",08/18/07 | |
2,"b",08/19/07 | |
3,"c",08/20/07 | |
4,"d",08/21/07 | |
5,"e",08/22/07 | |
6,"f",08/23/07 | |
7,"g",08/24/07 | |
8,"h",08/25/07 | |
9,"i",08/26/07 | |
# the result: | |
$ python csv_reader.py testdata.csv | |
['Title 1', 'Title 2', 'Title 3'] | |
['1', 'a', '08/18/07'] | |
['2', 'b', '08/19/07'] | |
['3', 'c', '08/20/07'] | |
['4', 'd', '08/21/07'] | |
['5', 'e', '08/22/07'] | |
['6', 'f', '08/23/07'] | |
['7', 'g', '08/24/07'] | |
['8', 'h', '08/25/07'] | |
['9', 'i', '08/26/07'] | |
# In addition to working with sequences of data, the csv module includes classes for working # with rows as dictionaries so that the fields can be named. The DictReader and DictWriter # # classes translate rows to dictionaries instead of lists. Keys for the dictionary can be # # passed in, or inferred from the first row in the input (when the row contains headers). | |
import csv | |
import sys | |
f = open(sys.argv[1], 'rt') | |
try: | |
reader = csv.DictReader(f) | |
for row in reader: | |
print row | |
finally: | |
f.close() | |
# returns: | |
$ python csv_dictreader.py testdata.csv | |
{'Title 1': '1', 'Title 3': '08/18/07', 'Title 2': 'a'} | |
{'Title 1': '2', 'Title 3': '08/19/07', 'Title 2': 'b'} | |
{'Title 1': '3', 'Title 3': '08/20/07', 'Title 2': 'c'} | |
{'Title 1': '4', 'Title 3': '08/21/07', 'Title 2': 'd'} | |
{'Title 1': '5', 'Title 3': '08/22/07', 'Title 2': 'e'} | |
{'Title 1': '6', 'Title 3': '08/23/07', 'Title 2': 'f'} | |
{'Title 1': '7', 'Title 3': '08/24/07', 'Title 2': 'g'} | |
{'Title 1': '8', 'Title 3': '08/25/07', 'Title 2': 'h'} | |
{'Title 1': '9', 'Title 3': '08/26/07', 'Title 2': 'i'} |
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