问 如何使用Python从JSON数组中删除元素？

第一个问题

但是，每当有两个以上的元素时，我输入任何高于两个的元素，它都不会删除任何内容。更糟糕的是，当我输入第一个时，它会删除除零索引之外的所有内容(每当数组中有两个以上的元素时)。

在 delete_data() 中，有两行代码读取 i = + 1 ，它只将 +1 (即 1 )指定给 i 。因此，你永远不会增加你的索引。您可能打算编写 i = i+1 或 i += 1 。

def delete_data():    # Deletes an element from the array
    view_data()
    new_data = []
    with open(filename, "r") as f:
        data = json.load(f)
        data_length = len(data) - 1
    print("Which index number would you like to delete?")
    delete_option = input(f"Select a number 0-{data_length}: ")
    i = 0
    for entry in data:
        if i == int(delete_option):
            i += 1  # <-- here
        else:
            new_data.append(entry)
            i += 1  # <-- and here
    with open(filename, "w") as f:
        json.dump(new_data, f, indent=4)

第二个问题:进一步改进

是否有更好的方法在我的Python脚本中实现这一点？

首先，您可以使用内置的 i 生成器手动增加 enumerate 。其次，您可以通过提供参数使函数可重用--代码示例中的文件名来自何处？

# view_data() should probably receive `filename` as a parameter
def view_data(filename: str):   # Prints JSON Array to screen
    with open(filename, "r") as f:
        data = json.load(f)
        # iterate over i and data simultaneously
        # alternatively, you could just remove i
        for i, item in enumerate(data):
            name = item["name"]
            chromebook = item["chromebook"]
            check_out = item["time&date"]
            print(f"Index Number: {i}")
            print(f"Name : {name}")
            print(f"Chromebook : {chromebook}")
            print(f"Time Of Checkout: {check_out} ")
            print("\n\n")
            # not needed anymore: i = i + 1
# view_data() should probably receive `filename` as a parameter
def delete_data(filename: str):    # Deletes an element from the array
    view_data()
    new_data = []
    with open(filename, "r") as f:
        data = json.load(f)
        data_length = len(data) - 1
    print("Which index number would you like to delete?")
    delete_option = input(f"Select a number 0-{data_length}: ")
    # iterate over i and data simultaneously
    for i, entry in enumerate(data):
        if i != int(delete_option):
            new_data.append(entry)
    with open(filename, "w") as f:
        json.dump(new_data, f, indent=4)

此外，你可以用一个列表理解来代替for-循环，有些人可能会认为它更"pythonic"：

new_data = [entry for i, entry in enumerate(data) if i != int(delete_option)]

有更简单的方法可以按索引从Python列表中删除元素。

给定 li = ["a", "b", "c"] ，您可以(至少)通过以下方式按索引删除元素1 ("b")：

li.pop(1) # pop takes an index (defaults to last) and removes and returns the element at that index
del li[1] # the del keyword will also remove an element from a list

下面是一些更新的代码：

def view_data():   # Prints JSON Array to screen
    with open(filename, "r") as f:
        data = json.load(f)
        i = 0
        for item in data:
            name = item["name"]
            chromebook = item["chromebook"]
            check_out = item["time&date"]
            print(f"Index Number: {i}")
            print(f"Name : {name}")
            print(f"Chromebook : {chromebook}")
            print(f"Time Of Checkout: {check_out} ")
            print("\n\n")
            i = i + 1
def delete_data():    # Deletes an element from the array
    view_data()
    with open(filename, "r") as f:
        data = json.load(f)
        data_length = len(data) - 1
    print("Which index number would you like to delete?")
    delete_option = input(f"Select a number 0-{data_length}: ")
    del data[int(delete_option)] # or data.pop(int(delete_option))