当我在代码块中创建文件时，为什么会出现“没有此类文件或目录错误？”

Question

我有一个要读取的csv文件目录，提取所需的信息，然后将其另存为另一个目录中的csv文件。我已经定义了代码块来完成所需的过程，但是在尝试测试一个文件时遇到了“无文件或目录”错误。据我所知，我正在代码中创建所需的文件，因此我不理解为什么文件不存在。

def writeFormPage(file, path):
    '''
    Input:
        Index CSV
    Output:
        Page CSV
    '''
    with open(file, 'r') as rf:
        reader = csv.reader(rf)

        base_name = os.path.basename(file)
        file_path = os.path.join(path, base_name)

        with open(file_path, 'w') as wf:
            writer = csv.writer(wf, delimiter = ',')

            for line in reader:
                url = line[-1]
                page_data = (parseFormPage(url))
                writer.writerow(page_data)

                time.sleep(3 + random.random() * 3)

os.chdir(PAGE_DIR)
demo_index_csv = '/Users/alexajones/index/2018Q4.csv'

# testing!!!
writeFormPage(demo_index_csv, PAGE_DIR)

FileNotFoundError                         Traceback (most recent call last)
<ipython-input-14-81e495544fd6> in <module>
      4 
      5 # testing!!!
----> 6 writeFormPage(demo_index_csv, PAGE_DIR)

<ipython-input-12-ff5447b72e24> in writeFormPage(file, path)
     13         file_path = os.path.join(path, base_name)
     14 
---> 15         with open(file_path, 'w') as wf:
     16             writer = csv.writer(wf, delimiter = ',')
     17 

FileNotFoundError: [Errno 2] No such file or directory: './page/2018Q4.csv'

我绝对可以确定我犯了一些愚蠢的错误，因为我是一个绝对的初学者，但是到目前为止我还没有找到它。我想确保代码能正常工作，因为最终我将编写一个循环以完成目录中所有csv文件的处理。任何帮助将不胜感激。

回应Barmar和Martineau的回答；我已经在程序中进一步创建了该子目录，一次创建了3个目录，尽管这些子目录存在很多“不存在”的问题。根据您的建议，我决定按需创建每个目录，如下所示，尽管我现在在一段可以正常工作的代码中出现“不存在”错误。这些目录在做什么错？附带说明，我需要这些在其他人的PC上工作，所以我无法指定整个路径。

# Create a new directory to hold CSV files
indx_dir = './index'
if not os.path.isdir(indx_dir):
    os.makedirs(indx_dir)
os.chdir(indx_dir)

#Create new list to store URLs from csv files
sec_urls = []

# For each csv file, open and locate URL in line 4 and add to newly created list
for filename in os.listdir(indx_dir):
    if filename.endswith('.csv'):
        with open(os.path.join(indx_dir, filename), newline='') as csvfile:
            reader = csv.reader(csvfile, delimiter=',')
            for line in reader:
                url = line[4].strip()
                sec_urls.append(url)
                print(url, 'downloaded and added to list')

---------------------------------------------------------------------------
FileNotFoundError                         Traceback (most recent call last)
<ipython-input-24-281ad84b64c7> in <module>
      3 
      4 # For each csv file, open and locate URL in line 4 and add to newly created list
----> 5 for filename in os.listdir(indx_dir):
      6     if filename.endswith('.csv'):
      7         with open(os.path.join(indx_dir, filename), newline='') as csvfile:

FileNotFoundError: [Errno 2] No such file or directory: './index'

Answer 1

谢谢巴尔马尔，这个问题现在已经解决。我最初询问的问题的代码已更改为：

# Define a function to collect form page data and save as a new csv file
def writeFormPage(file, path):
    '''
    Input:
        Index CSV
    Output:
        Page CSV
    '''
    with open(file, 'r') as rf:
        reader = csv.reader(rf)

        base_name = os.path.basename(file)
        file_path = os.path.join(path, base_name)

        with open(file_path, 'w') as wf:
            writer = csv.writer(wf, delimiter = ',')

            for line in reader:
                url = line[-1]
                page_data = (parseFormPage(url))
                writer.writerow(page_data)

                time.sleep(3 + random.random() * 3)

# Create a new directory to save new CSV files
page_dir = './page'
if not os.path.isdir(page_dir):
    os.makedirs(page_dir)
os.path.isdir(page_dir)

demo_index_csv = './index/2018Q4.csv'

# testing!!!
writeFormPage(demo_index_csv, page_dir)