如何遍历字符串列表并识别整数和浮点数，然后将它们添加到列表中？

Question

I am trying to iterate over list of strings to add both floats and ints to another list. My code below works for ints, but not for floats and I don't know why.

My pseudo code would be: for element in list, if element is float or int, add to list.

So in the code below I use these two inputs, but you will see the issues. How can I fix this?

theInput1 = "3.2+.4*5.67/6.145="
theInput2 = "11.897/3.4+9.2-0.4*6.9/12.6-16.7="

And here is my code below when I use the first input:

import re
a = "3.2+.4*5.67/6.145="
a2 = [x for x in re.split("(\d*\.?\d*)", a) if x != '']

s = []

for i in a2:
  if i >='0' and i <='9':
    s.append(i)

print(s)

This is the output that I get:

['3.2', '5.67', '6.145']

I'm not sure what happened to the 0.4?

The result for the second input:

['11.897', '3.4', '0.4', '6.9', '12.6', '16.7']

Again the 9.2 is missing...

For this input without floats it works fine:

"(12+3)*(56/2)/(34-4)="

I get this output which works:

['12', '3', '56', '2', '34', '4']

Answer 1

Another option is to use re.findall instead of split:

import re


def get_numbers(s):
    floats = []
    ints = []
    for x in re.findall(r"\d*\.?\d+", s):
        if '.' in x:
            floats.append(float(x))
        else:
            ints.append(int(x))
    return floats, ints


# For Display
print('Floats', get_numbers("11.897/3.4+9.2-0.4*6.9/12.6-16.7="))  # Floats Only
print('Ints  ', get_numbers("(12+3)*(56/2)/(34-4)="))  # Ints Only
print('Mixed ', get_numbers("(12+.3)*(56.36/2.15)/(34-4)="))  # Mixed

Output:

Floats ([11.897, 3.4, 9.2, 0.4, 6.9, 12.6, 16.7], [])
Ints   ([], [12, 3, 56, 2, 34, 4])
Mixed  ([0.3, 56.36, 2.15], [12, 34, 4])

---

The individual lists can be accessed like so:

f, i = get_numbers("(12+.3)*(56.36/2.15)/(34-4)=")

Answer 2

The problem is in comparison i <= "9" . Obviously "9.2" fails the check so it isn't added to the list.

You can try:

import re

a = "11.897/3.4+9.2-0.4*6.9/12.6-16.7="
a2 = [x for x in re.split(r"(\d*\.?\d*)", a) if x != ""]
s = []

for i in a2:
    try:
        s.append(float(i))
    except ValueError:
        continue

print(s)

Prints:

[11.897, 3.4, 9.2, 0.4, 6.9, 12.6, 16.7]