_name.lower

`_name.lower()` 是一个字符串的方法，用于将字符串中的所有字符转换为小写字母。

示例用法：

name = "Hello World"
lower_name = name.lower()
print(lower_name)  # 输出: hello world

在上述示例中，`lower()` 方法将字符串 `name` 中的所有字符转换为小写字母，并将结果赋给变量 `lower_name`。然后，通过 `print()` 函数打印出转换后的字符串 "hello world"。

相关问题

import os from PyQt5.QtCore import Qt from PyQt5.QtGui import QPixmap, QIcon from PyQt5.QtWidgets import QApplication, QWidget, QLabel, QVBoxLayout, QHBoxLayout, QTreeView, QFileSystemModel class ImageViewer(QWidget): def init(self, folder_path): super().init() self.folder_path = folder_path self.image_dict = {} self.current_image = None self.setWindowTitle("Image Viewer") self.setFixedSize(1000, 600) self.image_label = QLabel(self) self.image_label.setAlignment(Qt.AlignCenter) self.tree_view = QTreeView() self.tree_view.setMinimumWidth(250) self.tree_view.setMaximumWidth(250) self.model = QFileSystemModel() self.model.setRootPath(folder_path) self.tree_view.setModel(self.model) self.tree_view.setRootIndex(self.model.index(folder_path)) self.tree_view.setHeaderHidden(True) self.tree_view.setColumnHidden(1, True) self.tree_view.setColumnHidden(2, True) self.tree_view.setColumnHidden(3, True) self.tree_view.doubleClicked.connect(self.tree_item_double_clicked) self.main_layout = QHBoxLayout(self) self.main_layout.addWidget(self.tree_view) self.main_layout.addWidget(self.image_label) self.load_images() self.update_image() def load_images(self): for file_name in os.listdir(self.folder_path): if file_name.lower().endswith((".jpg", ".jpeg", ".png", ".gif", ".bmp")): file_path = os.path.join(self.folder_path, file_name) self.image_dict[file_name] = file_path current_image = list(self.image_dict.keys())[0] def update_image(self): if self.current_image is not None: pixmap = QPixmap(self.image_dict[self.current_image]) self.image_label.setPixmap(pixmap.scaled(self.width() - self.tree_view.width(), self.height(), Qt.KeepAspectRatio, Qt.SmoothTransformation)) def tree_item_double_clicked(self, index): file_name = self.model.fileName(index) if file_name in self.image_dict: self.current_image = file_name self.update_image() def keyPressEvent(self, event): if event.key() == Qt.Key_A: self.previous_image() elif event.key() == Qt.Key_D: self.next_image() elif event.key() in [Qt.Key_1, Qt.Key_2, Qt.Key_3, Qt.Key_4, Qt.Key_5]: self.save_text_file(event.key() - Qt.Key_0) def previous_image(self): if self.current_image is not None: file_names = list(self.image_dict.keys()) current_index = file_names.index(self.current_image) if current_index > 0: self.current_image = file_names[current_index - 1] else: self.current_image = file_names[-1] self.update_image() def next_image(self): if self.current_image is not None: file_names = list(self.image_dict.keys()) current_index = file_names.index(self.current_image) if current_index < len(file_names) - 1: self.current_image = file_names[current_index + 1] else: self.current_image = file_names[0] self.update_image() def save_text_file(self, number): if self.current_image is not None: file_name = self.current_image txt_file_path = os.path.join(self.folder_path, os.path.splitext(file_name)[0] + ".txt") with open(txt_file_path, "w") as file: file.write(str(number)) if name == "main": import sys app = QApplication(sys.argv) viewer = ImageViewer("D:/图片/wallpaper") viewer.show() sys.exit(app.exec_())这份代码实现不了使用键盘的A键向上翻页以及D键向下翻页，也实现不了键盘数字键生成相应txt文档，帮我分析一下错在哪里

这份代码在实现键盘事件的时候，使用了错误的函数名称。应该使用`keyPressEvent`而不是`key_press_event`函数。另外，在`save_text_file`函数中，应该先判断当前图片是否为`None`，再执行后续的代码。以下是修改后的代码：

import os 
from PyQt5.QtCore import Qt 
from PyQt5.QtGui import QPixmap, QIcon 
from PyQt5.QtWidgets import QApplication, QWidget, QLabel, QVBoxLayout, QHBoxLayout, QTreeView, QFileSystemModel 

class ImageViewer(QWidget): 
    def __init__(self, folder_path): 
        super().__init__() 
        self.folder_path = folder_path 
        self.image_dict = {} 
        self.current_image = None 
        self.setWindowTitle("Image Viewer") 
        self.setFixedSize(1000, 600) 
        self.image_label = QLabel(self) 
        self.image_label.setAlignment(Qt.AlignCenter) 
        self.tree_view = QTreeView() 
        self.tree_view.setMinimumWidth(250) 
        self.tree_view.setMaximumWidth(250) 
        self.model = QFileSystemModel() 
        self.model.setRootPath(folder_path) 
        self.tree_view.setModel(self.model) 
        self.tree_view.setRootIndex(self.model.index(folder_path)) 
        self.tree_view.setHeaderHidden(True) 
        self.tree_view.setColumnHidden(1, True) 
        self.tree_view.setColumnHidden(2, True) 
        self.tree_view.setColumnHidden(3, True) 
        self.tree_view.doubleClicked.connect(self.tree_item_double_clicked) 
        self.main_layout = QHBoxLayout(self) 
        self.main_layout.addWidget(self.tree_view) 
        self.main_layout.addWidget(self.image_label) 
        self.load_images() 
        self.update_image() 

    def load_images(self): 
        for file_name in os.listdir(self.folder_path): 
            if file_name.lower().endswith((".jpg", ".jpeg", ".png", ".gif", ".bmp")): 
                file_path = os.path.join(self.folder_path, file_name) 
                self.image_dict[file_name] = file_path 
        self.current_image = list(self.image_dict.keys())[0] 

    def update_image(self): 
        if self.current_image is not None: 
            pixmap = QPixmap(self.image_dict[self.current_image]) 
            self.image_label.setPixmap(pixmap.scaled(self.width() - self.tree_view.width(), self.height(), Qt.KeepAspectRatio, Qt.SmoothTransformation)) 

    def tree_item_double_clicked(self, index): 
        file_name = self.model.fileName(index) 
        if file_name in self.image_dict: 
            self.current_image = file_name 
            self.update_image() 

    def keyPressEvent(self, event): 
        if event.key() == Qt.Key_A: 
            self.previous_image() 
        elif event.key() == Qt.Key_D: 
            self.next_image() 
        elif event.key() in [Qt.Key_1, Qt.Key_2, Qt.Key_3, Qt.Key_4, Qt.Key_5]: 
            self.save_text_file(event.key() - Qt.Key_0) 

    def previous_image(self): 
        if self.current_image is not None: 
            file_names = list(self.image_dict.keys()) 
            current_index = file_names.index(self.current_image) 
            if current_index > 0: 
                self.current_image = file_names[current_index - 1] 
            else: 
                self.current_image = file_names[-1] 
            self.update_image() 

    def next_image(self): 
        if self.current_image is not None: 
            file_names = list(self.image_dict.keys()) 
            current_index = file_names.index(self.current_image) 
            if current_index < len(file_names) - 1: 
                self.current_image = file_names[current_index + 1] 
            else: 
                self.current_image = file_names[0] 
            self.update_image() 

    def save_text_file(self, number): 
        if self.current_image is not None: 
            file_name = self.current_image 
            txt_file_path = os.path.join(self.folder_path, os.path.splitext(file_name)[0] + ".txt") 
            with open(txt_file_path, "w") as file: 
                file.write(str(number)) 

if __name__ == "__main__": 
    import sys 
    app = QApplication(sys.argv) 
    viewer = ImageViewer("D:/图片/wallpaper") 
    viewer.show() 
    sys.exit(app.exec_()) 

请解释以下代码： module_name = d if d.find('DIV2K-Q') < 0 else 'DIV2KJPEG' m = import_module('data.' + module_name.lower()) testset = getattr(m, module_name)(args, train=False, name=d)

这段代码的作用是从 Python 的模块系统中加载一个模块并实例化一个类，用于进行某些任务。

首先，它通过判断字符串 `d` 中是否包含 'DIV2K-Q' 来决定模块的名称，如果不包含则模块名为 `d`，否则为 'DIV2KJPEG'。

然后，它通过使用内置的 `import_module` 函数加载了名称为 `'data.' + module_name.lower()` 的模块，其中 `module_name.lower()` 将模块名称转换为小写。

最后，它通过使用内置的 `getattr` 函数获取模块中名称为 `module_name` 的类，并使用这个类实例化一个对象 `testset`，最终的实例化方式为 `testset = getattr(m, module_name)(args, train=False, name=d)`。