Python create csv file if not exist

1._

with open[saveAddr + ".csv", 'a'] as allpckts:

If you want to check file exists

os.path.isfile['/path/to/csv']

#check
if dir exist
if not create it
def check_dir[file_name]:
   directory = os.path.dirname[file_name]
if not os.path.exists[directory]:
   os.makedirs[directory]

def save[file_name, records]:
   check_dir[file_name]
csv_file = open[file_name, 'w+']
csvWriter = csv.writer[csv_file, delimiter = ',']
count = 0
for record in records:
   csvWriter.writerow[[record]]
count += 1

print[count, " record saved to ", file_name]
return count enter code here

directory = os.path.abspath[os.path.join[os.path.curdir]]
save[directory + "/data/filename.csv", your_list]

In this article, we will discuss how to append a row to an existing csv file using csv module’s reader / writer & DictReader / DictWriter classes.,This writer object has a function writerow[] , pass the list to it and it will add list’s contents as a new row in the associated csv file,csv module provides a class writer, which can write lists into csv file as rows. Let’s see how to use it for appending a new row in csv,,csv module provides a class DictWriter, which can write dictionaries into csv file as rows. Let’s see how to use it for appending a new row in csv,

Suppose we have a CSV file students.csv, whose contents are,

Id, Name, Course, City, Session
21, Mark, Python, London, Morning
22, John, Python, Tokyo, Evening
23, Sam, Python, Paris, Morning

Suppose we have a list of strings,

# List of strings
row_contents = [32, 'Shaun', 'Java', 'Tokyo', 'Morning']

The above steps will append out list as a row in the csv. To make the process simple, we have created a separate function with the above steps,

from csv
import writer

def append_list_as_row[file_name, list_of_elem]:
   # Open file in append mode
with open[file_name, 'a+', newline = ''] as write_obj:
   # Create a writer object from csv module
csv_writer = writer[write_obj]
# Add contents of list as last row in the csv file
csv_writer.writerow[list_of_elem]

Last Updated : 26 Nov, 2020,Technical Scripter 2020

Let’s take one List that we want to add as a new row.

List = [6, 'William', 5532, 1, 'UAE']

Let’s take one Dictionary that we want to add as a new row.

dict = {
   'ID': 6,
   'NAME': 'William',
   'RANK': 5532,
   'ARTICLE': 1,
   'COUNTRY': 'UAE'
}

This program will create a new file named test.txt in the current directory if it does not exist. If it does exist, it is overwritten.,This method is not entirely safe. If an exception occurs when we are performing some operation with the file, the code exits without closing the file.,Writing a string or sequence of bytes [for binary files] is done using the write[] method. This method returns the number of characters written to the file.,In this tutorial, you'll learn about Python file operations. More specifically, opening a file, reading from it, writing into it, closing it, and various file methods that you should be aware of.

Python has a built-in open[] function to open a file. This function returns a file object, also called a handle, as it is used to read or modify the file accordingly.

>>> f = open["test.txt"] # open file in current directory >>>
   f = open["C:/Python38/README.txt"] # specifying full path

2._

f = open["test.txt"] # equivalent to 'r'
or 'rt'
f = open["test.txt", 'w'] # write in text mode
f = open["img.bmp", 'r+b'] # read and write in binary mode

Hence, when working with files in text mode, it is highly recommended to specify the encoding type.

f = open["test.txt", mode = 'r', encoding = 'utf-8']

If the file you specified does not exist, then the writing function creates and writes data to a new file.,If the file you specified does not exist, then the writing function creates a new file and writes the input data to the first sheet.,'overwrite' [default] — Overwrite the file.,If the file you specified does not exist, then the writing function performs the same actions as 'replacefile'.

T = table[['M';
   'F';
   'M'
], [45 45;41 32;40 34], ...{
   'NY';
   'CA';
   'MA'
}, [true;false;false]]

T = 3× 4 table
Var1 Var2 Var3 Var4
____ ________ ______ _____

M 45 45 {
   'NY'
}
true
F 41 32 {
   'CA'
}
false
M 40 34 {
   'MA'
}
false

Var1, Var2_1, Var2_2, Var3, Var4
M, 45, 45, NY, 1
F, 41, 32, CA, 0
M, 40, 34, MA, 0

writetable[T, 'myData.txt', 'Delimiter', ' ']
type 'myData.txt'