仅读取txt文件python中的数字

Question

I have a text file that contains these some words and a number written with a point in it. For example
hello! 54.123

Now I only want the number 54.123 to be extracted an converted so that the outcome is 54123

The code I tried is

import re
exp = re.compile(r'^[\+]?[0-9]')

my_list = []
with open('file.txt') as f:
    lines = f.readlines()
    for line in lines:
        if re.match(exp, line.strip()):
            my_list.append(int(line.strip()))

#convert to a string
listToStr = ' '.join([str(elem) for elem in my_list])
print(listToStr)

But this returns the error: ValueError: invalid literal for int() with base 10: '54.123'

Does anyone know a solution for this?

Answer 1

This may help I am now getting numbers from the file I guess you were trying to use split in place of strip

import re
exp = re.compile(r'[0-9]')

my_list = []
with open('file.txt') as f:
    lines = f.readlines()
    for line in lines:
        for numbers in line.split():
            if re.match(exp, numbers):
                my_list.append(numbers)

#convert to a string
listToStr = ' '.join([str(elem) for elem in my_list])
print(listToStr)

Answer 2

You can check if a given line is a string representing a number using the isdigit() function.

From what I can tell you need to just check if there is a number as isdigit() works on integers only (floats contain "." which isn't a number and it returns False).

For example:

def numCheck(string):
  # Checks if the input string contains numbers
  return any(i.isdigit() for i in string)

string = '54.123'
print(numCheck(string)) # True

string = 'hello'
print(numCheck(string)) # False

Note: if your data contains things like 123ab56 then this won't be good for you.

---

To convert 54.123 to 54123 you could use the replace(old, new) function.

For example:

string = 54.123
new_string = string.replace('.', '') # replace . with nothing
print(new_string) # 54123

Answer 3

You can try to convert the current line to a float. In case the line does not contain a legit float number it returns a ValueError exception that you can catch and just pass. If no exception is thrown just split the line at the dot, join the 2 parts, convert to int and add to the array.

my_list = []
with open('file.txt') as f:
    lines = f.readlines()
    for line in lines:
        try:
            tmp = float(line)
            num = int(''.join(line.split(".")))
            my_list.append(num)
        except ValueError:
            pass

#convert to a string
listToStr = ' '.join([str(elem) for elem in my_list])
print(listToStr)