条件文件加载和标签 python

Question

我正在尝试制作一个从目录加载某些图像的函数。条件是如果图像名称包含特定数字，则应将其作为对象加载（具有名称和数字）。

这是我目前所做的：

get_image_data([71,72,82,105...])
directory = os.listdir("/Users/Me/Desktop/path2images/")


#Sample of files
0070_pressure_pred.png 
0070_pressure_target.png 
0070_velX_pred.png 
0070_velX_target.png 
0070_velY_pred.png 
0070_velY_target.png 
0071_pressure_pred.png 
0071_pressure_target.png 
0071_velX_pred.png 
0071_velX_target.png 
0071_velY_pred.png 
0071_velY_target.png 
0072_pressure_pred.png 
0072_pressure_target.png 
0072_velX_pred.png

函数：

def get_pressure_prediction(file_numbers):
#takes  a list of image number and returns them 
for files in directory:
    for x in file_numbers:
        if str(x) in files[:4]:
            print("File '{}' matched".format(files))  #Code functions fine until here
            if str(pressure_pred) in files:
                "pp{}".format(x) = mpimg.imread(path + files) #attempting to load image and label it with pp{image number}
            elif str(pressure_target) in files:
                "pt{}".format(x) = mpimg.imread(path + files)
            elif str(velX_pred) in files:
                "vxp{}".format(x) = mpimg.imread(path + files)
            elif str(velX_target) in files:
                "vxt{}".format(x) = mpimg.imread(path + files)
            elif str(velY_pred) in files:
                "vyp{}".format(x) = mpimg.imread(path + files)
            elif str(velY_target) in files:
                "vyt{}".format(x) = mpimg.imread(path + files)   
            break

我收到此错误消息：

    "vyt{}".format(x) = mpimg.imread(path + files)
^
SyntaxError: can't assign to function call

Answer 1

您不能为字符串（"vyt{}".format(x) 是字符串）分配另一个值。我建议您将函数输出分配给字典中的指定键：

mapping = dict()
if str(pressure_pred) in files:
                mapping["pp{}".format(x)] = mpimg.imread(path + files) 
elif ...
...

# You will have to change it in all your conditions
# and then you will be able to access it as follows:
res = mapping["vytX"] # where vytX is the desired variable

Answer 2

您不能有条件地标记变量。

"pp{}".format(x) 是一个字符串，变量名不能是字符串。例如 "foo" = 0 会给你一个语法错误。

这是另一个不起作用的例子：

for i in range(5):
    "variable{i}" = i

我建议创建一个 class 来存储图像的名称和路径，然后将图像附加到列表中，然后您可以对列表中的图像做任何您想做的事情。示例：

class Image:
    def __init__(self, label, filePath):
        self.label = label
        self.image = mpimg.imread(filePath)

images = []  

if str(x) in files[:4]:
    print("File '{}' matched".format(files))  
    if str(pressure_pred) in files:
        images.append(Image("pp{}".format(x), path + files)) 
    elif str(pressure_target) in files:
        images.append(Image("pt{}".format(x), path + files))
    elif str(velX_pred) in files:
        images.append(Image("vxp{}".format(x), path + files))
    elif str(velX_target) in files:
        images.append(Image("vxt{}".format(x), path + files))
    elif str(velY_pred) in files:
        images.append(Image("vyp{}".format(x), path + files))
    elif str(velY_target) in files:
        images.append(Image("vyt{}".format(x), path + files))
    break

条件文件加载和标签 python

Conditional file loading and labeling python

python

if-statement

format-string

python-3.x