Python csv.reader: How do I return to the top of the file?
PythonCsvPython Problem Overview
When I'm moving through a file with a csv.reader, how do I return to the top of the file. If I were doing it with a normal file I could just do something like "file.seek(0)". Is there anything like that for the csv module?
Thanks ahead of time ;)
Python Solutions
Solution 1 - Python
You can seek the file directly. For example:
>>> f = open("csv.txt")
>>> c = csv.reader(f)
>>> for row in c: print row
['1', '2', '3']
['4', '5', '6']
>>> f.seek(0)
>>> for row in c: print row # again
['1', '2', '3']
['4', '5', '6']
Solution 2 - Python
You can still use file.seek(0). For instance, look at the following:
import csv
file_handle = open("somefile.csv", "r")
reader = csv.reader(file_handle)
# Do stuff with reader
file_handle.seek(0)
# Do more stuff with reader as it is back at the beginning now
This should work since csv.reader is working with the same.
Solution 3 - Python
I've found the csv.reader and csv.DictReader a little difficult to work with because of the current line_num. making a list from the first read works well:
>>> import csv
>>> f = open('csv.txt')
>>> lines = list( csv.reader(f) ) # <-- list from csvReader
>>>
>>> for line in lines:
... print(line)
['1', '2', '3']
['4', '5', '6']
>>>
>>> for line in lines:
... print(line)
['1', '2', '3']
['4', '5', '6']
>>>
>>>lines[1]
['4', '5', '6']
this captures the optional first row used by the dictReader but lets you work with the list again and again and even inspect individual rows.