在 Python 中，我的 .split() 行中有一个值错误，returns 1 expected 2。添加白色 space 没有帮助。 data.txt 有问题？

Question

如果该标题含糊不清，我们深表歉意。首先，我想说的是，我已经通读了所有我能找到的关于 python 中的值错误的论坛，我已经实现了它们，但我的程序仍然无法通过第 22 行。在底部但首先我会给你 "DL" 哈哈。

我正在编写一个读取 data.txt 文件并显示输出的程序。这是项目的目标

Your output should look like: Reading vertices for a polygon with 5 vertices... Vertex 1 has coordinates at (1.70, 4.90) Vertex 2 has coordinates at (6.10, 6.20) Vertex 5 has coordinates at (1.50, 1.40)

Reading vertices for a rectangle having, (of course), 4 vertices... Vertex 1 has coordinates at (7.00, 5.00) ... Your program only needs to echo check the data; there is no requirement during this lab to construct polygon objects, rectangle objects, to do transformations, to undo transformations, or to find and print perimeter.

我的命令行错误是：

Reading vertices for polygon with 5 vertices...
Vertex 1 has coordinates at (1.7, 4)
Vertex 2 has coordinates at (.9, 6.1)
Vertex 3 has coordinates at (6.2, 7.0)
Vertex 4 has coordinates at (2.8, 4.8)
Vertex 5 has coordinates at (0.1, 1.)
Reading vertices for polygon with 1 vertices...
Traceback (most recent call last):
File "Read.py", line 22, in <module>
  x, y = file.read(8).split( )
  ValueError: too many values to unpack (expected 2)

我写的代码是：

file = open("data.txt")

line = file.read(1).strip()

while line != 'Q':

    numVertices = file.read(3).strip()
    numVertices = int(numVertices)

if numVertices != 4:
    print("Reading vertices for polygon with " + 
str(numVertices) + " vertices...") 

else:
    print("Reading vertices for rectangle having " + 
str(numVertices) + " vertices...")

for i in range(int(numVertices)):

    x, y = file.read(8).split( )
    print("Vertex " + str(i + 1) + " has coordinates at (" + x + ", " + y + ")")

line = file.read(1).strip()

file.close()

并且 data.txt 文件包含：

P  5
1.7   4.9
6.1  6.2
7.0  2.8
4.8  0.1
1.5  1.4
R  4
7.0  5.0
1.0  5.0
1.0  3.0
7.0  3.0
P  4
4.1  5.4
6.9  2.5
2.9  0.8
0.9   2.5
P  3
1.2  4.7
6.5  4.2
4.0  1.7
Q

在第 22 行我尝试添加到 .split()，我添加了 (" "), (", ") none 其中成功了。我试图将变量从 int 更改为 float，但我无法连接字符串。所以我很茫然，有人介意帮我找出问题所在吗？非常感谢！

Answer 1

我修复了您代码中的缩进，凭直觉知道 while 循环在文件处理中结束的位置。我还更改了 file 变量名称，因为 file 是您所做的预定义类型 而不是 真的想重新定义。

该程序似乎有效。

in_file = open("data.txt")

line = in_file.read(1).strip()

while line != 'Q':

    numVertices = in_file.read(3).strip()
    numVertices = int(numVertices)

    if numVertices != 4:
        print("Reading vertices for polygon with " +
    str(numVertices) + " vertices...")

    else:
        print("Reading vertices for rectangle having " +
    str(numVertices) + " vertices...")

    for i in range(int(numVertices)):

        x, y = in_file.read(8).split( )
        print("Vertex " + str(i + 1) + " has coordinates at (" + x + ", " + y + ")")

    line = in_file.read(1).strip()

in_file.close()

输出：

Reading vertices for polygon with 5 vertices...
Vertex 1 has coordinates at (1.7, 4.9)
Vertex 2 has coordinates at (6.1, 6.2)
Vertex 3 has coordinates at (7.0, 2.8)
Vertex 4 has coordinates at (4.8, 0.1)
Vertex 5 has coordinates at (1.5, 1.4)
Reading vertices for rectangle having 4 vertices...
Vertex 1 has coordinates at (7.0, 5.0)
Vertex 2 has coordinates at (1.0, 5.0)
Vertex 3 has coordinates at (1.0, 3.0)
Vertex 4 has coordinates at (7.0, 3.0)
Reading vertices for rectangle having 4 vertices...
Vertex 1 has coordinates at (4.1, 5.4)
Vertex 2 has coordinates at (6.9, 2.5)
Vertex 3 has coordinates at (2.9, 0.8)
Vertex 4 has coordinates at (0.9, 2.5)
Reading vertices for polygon with 3 vertices...
Vertex 1 has coordinates at (1.2, 4.7)
Vertex 2 has coordinates at (6.5, 4.2)
Vertex 3 has coordinates at (4.0, 1.7)

Answer 2

您的代码存在问题，它需要非常指定的格式。观察你的所作所为：

read(1)

正好读取一个字节。大概期待 polygon/quit 的类型。那么：

read(3).strip()

为什么是 3 个字节？好吧，您可能希望字母后有一个 space，然后是指定顶点数量的数字，必须为 1 位，最后是换行符。总共 3 个字节。最后，对于每个顶点，你

read(8)

8 个字节 - 每个坐标（数字、小数点、数字）3 个字节，它们之间有一个 space，最后是新行。

如果有任何字符不合适，它会破坏你的代码。您期待准确的格式。如果您不必使用 read，那么就不要使用 - 有更简单的方法，特别是逐行阅读。如果必须使用读取，请确保文件格式正确。您提供的示例中至少有 2 spaces，并且 有时有 3 spaces - 这会破坏您的代码。最后，始终尝试使用打印调试小程序 - 放入 for 循环：

for i in range(int(numVertices)):
    res = file.read(8).split()
    print(res)
    x,y = res

会准确地打印出您正在中断的内容，并为您提供有关如何继续的提示。

Answer 3

Welp 好像问题解决了。

我正在研究它并想出了替代解决方案。

喜欢的话点个赞吧，我来分解我的方法

file = open("data.txt")

line = file.readlines()
for i in range(len(line)):
    if 'P' in line[i] or 'R' in line[i]:
        x = line[i].split()
        n_verts = x[1]
        n_verts = int(n_verts)
        print("-"*47)
        print(f"Reading vertices for polygon with {n_verts} vertices...\n")
        for a in range(1, n_verts + 1): 
            verts = line[i+a].split()
            verts = ', '.join(verts)
            print(f"Vertex {a} has coordinates ({verts})")

-----------------------------------------------
Reading vertices for polygon with 5 vertices...

Vertex 1 has coordinates (1.7, 4.9)
Vertex 2 has coordinates (6.1, 6.2)
Vertex 3 has coordinates (7.0, 2.8)
Vertex 4 has coordinates (4.8, 0.1)
Vertex 5 has coordinates (1.5, 1.4)
-----------------------------------------------
Reading vertices for polygon with 4 vertices...

Vertex 1 has coordinates (7.0, 5.0)
Vertex 2 has coordinates (1.0, 5.0)
Vertex 3 has coordinates (1.0, 3.0)
Vertex 4 has coordinates (7.0, 3.0)
-----------------------------------------------
Reading vertices for polygon with 4 vertices...

Vertex 1 has coordinates (4.1, 5.4)
Vertex 2 has coordinates (6.9, 2.5)
Vertex 3 has coordinates (2.9, 0.8)
Vertex 4 has coordinates (0.9, 2.5)
-----------------------------------------------
Reading vertices for polygon with 3 vertices...

Vertex 1 has coordinates (1.2, 4.7)
Vertex 2 has coordinates (6.5, 4.2)
Vertex 3 has coordinates (4.0, 1.7)

在 Python 中，我的 .split() 行中有一个值错误，returns 1 expected 2。添加白色 space 没有帮助。 data.txt 有问题？

In Python, I have a Value Error in my line with .split(), returns 1 expected 2. Adding white space doesn't help. Issue with data.txt?

python

command-line

compiler-errors

readfile

valueerror