如何在正则表达式中定义几个浮点组？

Question

I would like to match a string such as :

 k-point    1 :    0.00000000 0.00000000 0.00000000     weight = 0.01562500

I wrote that regex :

kpt_patt = re.compile("^\s*k-point\s+(\d+) :\s+" +
                      "([+-]?\d+\.\d+)\s+" +
                      "([+-]?\d+\.\d+)\s+" +
                      "([+-]?\d+\.\d+)\s+" +
                      "weight = (\d+\.\d+)")

line = " k-point    1 :    0.00000000 0.00000000 0.00000000     weight = 0.01562500"
m = kpt_patt.match(line)
print(m.groups())

In [1]: m.groups()
Out[1]: ('1', '0.00000000', '0.00000000', '0.00000000', '0.01562500')

It works but is there a better way to said that I want this group ([+-]?\\d+\\.\\d+)\\s+ several times ? Or a better way to write the whole regex of course.

Answer 1

Use string multiplication. I've added the r prefix to your regex strings.

float_rx = r"([+-]?\d+\.\d+)\s+"

kpt_patt = re.compile(r"^\s*k-point\s+(\d+) :\s+" +
                      float_rx * 3 +
                      r"weight = (\d+\.\d+)")

Also, your regex will not match numbers like .123 or 1 . You may or may not care about this. This is what I typically use to match a float: r"(\\d+(?:\\.\\d*)?|\\.\\d+)" . It will match numbers of these forms: 1 , 1. , 1.1 , and .1 , without matching . .