"[Errno 2] No such file or directory" Issue

Question

So my prof. gave me this code as the solution of my homework but when I run it it gives me an error. Can you please help me out? I guess I didn't specify the location of the file but not sure if that's the case.The objective of this question is to generate and read files that contain a list of random numbers.

import random
import os
import time


def fillFile(fileSize, fileName):

    # Delete file if exists
    if os.path.exists(fileName):
        os.remove(fileName)
    # Open file
    FILE = open(fileName, "w")

    # Write to file
    for i in range(fileSize):
        r = random.randint(0,fileSize+1000)
        FILE.write(str(r) + "\n")
    FILE.close()


def readFile(fileName):
    # Open file
    if os.path.exists(fileName):
        FILE = open(fileName,"r")
    else:
        print(fileName + " does not exist!")
        exit()

    # Read File
    alist = []
    for line in FILE:
        alist.append(int(line))

    FILE.close()

    return alist


def mainForFiles():
    # Dosyaları oluştur
    fileSizes = [1000, 5000, 10000, 25000, 50000, 100000, 200000]
    dirName = ".\\filesForAssignment1\\"

    # Delete fileStats.txt file if exists
    statFileName = "fileStats.txt"
    if os.path.exists(statFileName):
        os.remove(statFileName)

    # open stat file
    statFile = open(statFileName, "w")
    statFile.write("fillFile")

    print("WRITING TO FILES")

    for i in fileSizes:
        start = time.time()
        fillFile(i, dirName+"file"+str(i))
        finish = time.time()

        statFile.write("  " + str(finish-start))
        print("File Size = " + str(i) + "   Write Time = " + str(finish-start))

    statFile.write("\n")

    print("READING FILES")
    statFile.write("readFile")

    for i in fileSizes:

        fileName = dirName+"file"+str(i)

        # Dosyayı oku
        finish = time.time()
        alist = readFile(fileName)
        start = time.time()

        statFile.write("  " + str(finish-start))
        print ("File Size = " + str(i)+ "   Dosya Okuma Zamanı = " + str(finish-start))

    statFile.write("\n")
    statFile.close()


mainForFiles()

  File "C:/Users/emrea/PycharmProjects/helloworld/hello2.py", line 84, in 
<module>
    mainForFiles()
  File "C:/Users/emrea/PycharmProjects/helloworld/hello2.py", line 57, in mainForFiles
    fillFile(i, dirName+"file"+str(i))
  File "C:/Users/emrea/PycharmProjects/helloworld/hello2.py", line 12, in fillFile
    FILE = open(fileName, "w")
FileNotFoundError: [Errno 2] No such file or directory: '.\\filesForAssignment1\\file1000'

Answer 1

FileNotFoundError: [Errno 2] No such file or directory: '.\\filesForAssignment1\\file1000'

The w mode causes the file to be created if it doesn't exist (and truncated if it does so the os.remove is not actually useful there), however it does expect intermediate directories to exist.

This means you should ensure the path to the file ('.\\filesForAssignment1) does exist before trying to create the file.

os.makedirs(os.path.dirname(fileName), exists_ok=True)

should do the trick, or

pathlib.Path(fileName).parent.mkdir(parents=True, exists_ok=True)

for a somewhat more modern take on it.

There's a bunch of other minor issues in the script:

• the main function should generally be "gated" so modules can be imported without running them
• explicitly closing files has fallen out of favor as it's unreliable
• when opening files in "text" mode (the default) you should always provide an encoding
• pathlib is fun, also that way you should not have to deal with path separators and all that crap
• unless it's required to handle that case, I'd just let open(fname, 'r') error out if the file doesn't exist

Here's a version I think should be slightly improved:

import pathlib
import random
import os
import time


def fillFile(fileSize, fileName):
    with fileName.open('w', encoding='utf-8') as f:
        for i in range(fileSize):
            r = random.randint(0,fileSize+1000)
            f.write(f"{r}\n")

def readFile(fileName):
    with fileName.open(encoding='utf-8') as f:
        return [int(line) for line in f]

OUT_DIR = pathlib.Path.cwd().joinpath("filesForAssignment1")
FILE_SIZES = [1000, 5000, 10000, 25000, 50000, 100000, 200000]
def mainForFiles():
    # Dosyaları oluştur
    OUT_DIR.mkdir(parents=True, exist_ok=True) # make sure the directory exists

    statFilePath = pathlib.Path("fileStats.txt")
    with statFilePath.open('w', encoding='utf-8') as statFile:
        statFile.write("fillFile")

        print("WRITING TO FILES")

        for i in FILE_SIZES:
            start = time.time()
            fillFile(i, OUT_DIR.joinpath(f'file{i}'))
            finish = time.time()

            statFile.write(f"  {finish-start}")
            print(f"File Size = {i}   Write Time = {finish-start})")

        statFile.write("\n")

        print("READING FILES")
        statFile.write("readFile")

        for i in FILE_SIZES:
            f = OUT_DIR.joinpath(f'file{i}')

            # Dosyayı oku
            start = time.time()
            alist = readFile(f)
            finish = time.time()

            statFile.write(f"  {finish-start}")
            print (f"File Size = {i}   Dosya Okuma Zamanı = {finish-start}")

        statFile.write("\n")

if __name__ == '__main__':
    mainForFiles()

Answer 2

exit() is not doing what you want, it continues with the code.

def readFile(fileName):
    # Open file
    if os.path.exists(fileName):
        FILE = open(fileName,"r")
    else:
        print(fileName + " does not exist!")

        return

    # Read File
    alist = []
    for line in FILE:
        alist.append(int(line))

    FILE.close()

    return alist