FILES
Opening a file in write mode clears out old data if the files exists.
# Open a file in wrrite mode (default is read)
#
# The old data is cleared if the files exists.
# If the file doesn't exists a new one is created.
#
# The os module ...
# provides functions for working with files and directories.
import os
dir_path = os.path.dirname(os.path.realpath(__file__))
file = dir_path + "/data/myfile1.txt"
fp = open(file, "w")
fp.write("New line 1 \n")
fp.write("New line 2 \n")
fp.close()
f = open(file)
print(f.read())
# New line 1
# New line 2
Csv
The os module provides functions for working with files and directories.
# Write and read csv
import os
import csv
DIR = os.path.dirname(os.path.realpath(__file__))
FILE = DIR + "/data/myfile2.csv"
f = open(FILE, "w")
f.write("c1, c2, c3 \n")
f.write("11, 12, 13 \n")
f.write("12, 22, 23 \n")
f.write("13, 32, 33 \n")
f.close()
f = open(FILE, "r")
assert f.readline().strip() == "c1, c2, c3"
assert f.readline().strip() == "11, 12, 13"
# Walk - Read directories and files
for root, dirs, files in os.walk(DIR + "/data/"):
for name in files:
if name.endswith(".csv"):
path = os.path.join(root, name)
assert path.endswith(".csv")
assert name == "myfile2.csv"
# Csv - reader
file = DIR + "/data/myfile2.csv"
data = list(csv.reader(open(file), delimiter=","))
assert data[0] == ['c1', ' c2', ' c3 ']
assert data[1] == ['11', ' 12', ' 13 ']
Exceptions
A lot of things can go wrong when working with files.
# Exception
#
# Handling an error with try statement is called ...
# catching an exception.
try:
fp = open("/var/www/python/") # Error: not a file
except:
print("Error: not a file")
Last update: 302 days ago
