Python读取CSV文件报错：文件未找到问题求助

Hey there, let's troubleshoot why your rail length data file isn't being recognized by Python—even after moving it to the D drive. Here are the most likely issues and fixes:

1. Escape Character Messing Up Your Path #

On Windows, the backslash \ in file paths is an escape character (like \r gets interpreted as a carriage return). That means your path 'd:\rail-length-km-at-end-of-year' isn't being read correctly by Python.

Fix it in one of three ways:

• Use double backslashes: 'd:\\rail-length-km-at-end-of-year.csv'
• Use a raw string (prefix with r): r'd:\rail-length-km-at-end-of-year.csv'
• Use forward slashes instead: 'd:/rail-length-km-at-end-of-year.csv'

2. Missing File Extension #

Did you forget to add the .csv suffix? If your actual file is named rail-length-km-at-end-of-year.csv (most CSV files have this extension), your code is looking for a file with no extension at all—hence the "not found" error.

3. Verify the Exact File Path #

Double-check that you're using the correct filename and path. You can:

• Right-click the CSV file → Go to Properties → Copy the full path from the "Location" field
• Paste that exact path into your code (making sure to handle escape characters as mentioned above)

Modified Working Code #

Here's your code with the path fixed (using raw string and adding .csv—adjust if your filename has a different extension):

import numpy as np
import matplotlib.pyplot as plt

title = "Length of rails"
titlelen = len(title)
print("{:*^{titlelen}}".format(title, titlelen=titlelen+6))
print()

# Fixed path using raw string and adding .csv extension
data = np.genfromtxt(r'd:\rail-length-km-at-end-of-year.csv', 
                     skip_header=1, 
                     dtype=[('year','U10'),('rail_type','U50'), ('length','i8')], 
                     delimiter=",", 
                     missing_values=['na','-'],
                     filling_values=[0])

x_public = data[data['rail_type']=='public sector']['year']
y_public = data[data['rail_type']=='public sector']['length']
x_private = data[data['rail_type']=='Private Sector']['year']
y_private = data[data['rail_type']=='Private Sector']['length']

fig = plt.figure()
ax1 = fig.add_subplot(111)
ax1.plot(x_public, y_public, c='b', label='Public Sector')
ax1.plot(x_private,y_private, c='r', label='Private Sector')
plt.ylabel('rail length')
plt.legend(loc='upper left')
plt.show()

Quick Debug Tip #

If you're still stuck, run this to check Python's current working directory—maybe it's looking in the wrong place by default:

import os
print(os.getcwd())

内容的提问来源于stack exchange，提问作者Askar Mujhib