想要将复数的文本文件转换为Python中的数字列表

Question

I have a text file of complex numbers called output.txt in the form:

[-3.74483279909056 + 2.54872970226369*I]
[-3.64042002652517 + 0.733996349939531*I]
[-3.50037473491252 + 2.83784532111642*I]
[-3.80592861109028 + 3.50296053533826*I]
[-4.90750592116062 + 1.24920836601026*I]
[-3.82560512449716 + 1.34414866823615*I]
etc...

I want to create a list from these (read in as a string in Python) of complex numbers.

Here is my code:

data = [line.strip() for line in open("output.txt", 'r')]
for i in data:
    m = map(complex,i)

However, I'm getting the error:

ValueError: complex() arg is a malformed string

Any help is appreciated.

Answer 1

From the help information, for the complex builtin function:

>>> help(complex)
class complex(object)
 |  complex(real[, imag]) -> complex number
 |
 |  Create a complex number from a real part and an optional imaginary part.
 |  This is equivalent to (real + imag*1j) where imag defaults to 0.

So you need to format the string properly, and pass the real and imaginary parts as separate arguments.

---

Example:

num = "[-3.74483279909056 + 2.54872970226369*I]".translate(None, '[]*I').split(None, 1)
real, im = num
print real, im
>>> -3.74483279909056 + 2.54872970226369
im = im.replace(" ", "") # remove whitespace
c = complex(float(real), float(im))
print c
>>> (-3.74483279909+2.54872970226j)

Answer 2

Try this:

numbers = []
with open("output.txt", 'r') as data:
    for line in data.splitlines():
        parts = line.split('+')
        real, imag = tuple( parts[0].strip(' ['), parts[1].strip(' *I]') )
        numbers.append(complex(float(real), float(imag)))

The problem with your original approach is that your input file contains lines of text that complex() does not know how to process. We first need to break each line down to a pair of numbers - real and imag. To do that, we need to do a little string manipulation (split and strip). Finally, we convert the real and imag strings to floats as we pass them into the complex() function.

Answer 3

这是创建复杂值列表的简洁方法（基于dal102答案）：

data = [complex(*map(float,line.translate(None, ' []*I').split('+'))) for line in open("output.txt")]