Python脚本执行报错：文件路径中出现多余的'b'字符

运行代码时出现如下报错：

Could not load source layer for INPUT: G:\Dropbox\temp\worklayers\b'hej0.tif' not found

相关代码片段：

# %% Definitions

path_root = normpath(r'G:\Dropbox\temp\')
path_start = normpath(r'G:\Dropbox\temp\worklayers\')
path_temp = normpath(r'G:\Dropbox\temp\templayers\')
path_temp2 = normpath(r'G:\Dropbox\temp\temp2layers\')
path_end = normpath(r'G:\Dropbox\temp\resultlayers\')
path_doc = normpath(r'G:\Dropbox\Documents\')

directory = os.fsencode(path_start)

df = pd.read_csv(path_doc+'\\DEM_masterfile.csv')

slope_list = [4, 4.9, 5.9, 7.1, 8.2, 10, 11.8, 13.8, 15.7, 17.9, 20.6, 25]
aspect_list_1 = [[0, 15], [15,30], [30, 45], [45, 60], [60, 75], [75, 90], [90, 105], [105, 120], [120, 135], [135, 150], [150, 165], [165, 180]]
aspect_list_2 = [[180, 195], [195, 210], [210, 225], [225, 240], [240, 255], [255, 270], [270, 285], [285, 300], [300, 315], [315, 330], [330, 345], [345, 360]]

# %% Generating the slope and aspect vector files from the DEM raster

for number in os.listdir(directory):
    
    processing.run("native:slope", {'INPUT':path_start+'\\'+str(number),'Z_FACTOR':1,'OUTPUT':path_temp+'\\'+'slope_'+str(number)})
    processing.run("native:aspect", {'INPUT':path_start+'\\'+str(number),'Z_FACTOR':1,'OUTPUT':path_temp+'\\'+'aspect_'+str(number)})

原因分析 #

报错里的"b"来自字节串的字符串转换：

• os.fsencode(path_start)会把路径转成字节串（bytes类型）
• os.listdir(directory)遍历返回的每个number都是字节串对象，比如b'hej0.tif'
• 当你用str(number)转换时，Python会把字节串的表示形式转成字符串，也就是直接带上b'...'的格式，拼接路径后就出现了多余的"b"。

解决方案 #

有两种可行的修复方式：

方式1：直接遍历字符串路径（推荐） #

去掉os.fsencode，直接用原始字符串路径遍历，得到的文件名本身就是字符串：

# 移除os.fsencode相关代码，直接遍历path_start
for filename in os.listdir(path_start):
    # 用os.path.join拼接路径，避免手动加斜杠的问题
    input_path = os.path.join(path_start, filename)
    slope_output = os.path.join(path_temp, f'slope_{filename}')
    aspect_output = os.path.join(path_temp, f'aspect_{filename}')
    
    processing.run("native:slope", {'INPUT': input_path, 'Z_FACTOR':1, 'OUTPUT': slope_output})
    processing.run("native:aspect", {'INPUT': input_path, 'Z_FACTOR':1, 'OUTPUT': aspect_output})

方式2：解码字节串为字符串 #

如果必须保留os.fsencode，需要把遍历到的字节串解码成正常字符串：

directory = os.fsencode(path_start)
for number in os.listdir(directory):
    # 把字节串解码为字符串（编码格式可根据系统调整，一般用utf-8即可）
    filename = number.decode('utf-8')
    input_path = os.path.join(path_start, filename)
    slope_output = os.path.join(path_temp, f'slope_{filename}')
    aspect_output = os.path.join(path_temp, f'aspect_{filename}')
    
    processing.run("native:slope", {'INPUT': input_path, 'Z_FACTOR':1, 'OUTPUT': slope_output})
    processing.run("native:aspect", {'INPUT': input_path, 'Z_FACTOR':1, 'OUTPUT': aspect_output})

额外建议：尽量用os.path.join拼接路径，比手动加\\更可靠，也能适配不同操作系统的路径分隔符。

内容的提问来源于stack exchange，提问作者Tobias Bowley