Parse flat-file (positional text-file) to read the wavelength

Question

I have the next txt with data:

FI R       83.0000m   34.960    1.1262      Fe 2      1.32055m   33.626    0.0522      N  
2      5754.61A   33.290    0.0241
TI R       1800.00m   33.092    0.0153      Fe 2      1.24854m   32.645    0.0054      N  
2      915.612A   31.997    0.0012
NI Ra      2.85000m   36.291   24.1132      Fe 2      7637.54A   33.077    0.0147      

what I want is to obtain the third column, is the wavelength of the emergent line, but my problem is when I put the condition in the if.

Name1,ion1,wavelength1,da1,de1,name2,ion2,
wavelength2,da2,de2,name3,ion3,wavelength3,da3,de3=np.genfromtxt('Emergent_line.txt', 
skip_header=3, delimiter="", unpack=True)

if(Name1=="Fe" and ion1==2):
    print(wavelength1)
elif(name2=="Fe" and ion2==2):
    print(wavelength2)
elif(name3=="Fe" and ion3==2):
    print(wavelength3)

In the txt I want to find the wavelength for Fe 2, but I think the problem is that the wavelength have a letter in the end, I don't want to delete, because I have a large list like that. I tried another froms, but I haven't solved it.

Answer 1

I think you are better off using regex

Example:

import re


text = '''FI R       83.0000m   34.960    1.1262      Fe 2      1.32055m   33.626    0.0522      N  
2      5754.61A   33.290    0.0241
TI R       1800.00m   33.092    0.0153      Fe 2      1.24854m   32.645    0.0054      N  
2      915.612A   31.997    0.0012
NI Ra      2.85000m   36.291   24.1132      Fe 2      7637.54A   33.077    0.0147'''

find_this = re.findall('(Fe 2.*?[0-9].*?)\s', text)
print(find_this)

Output:

['Fe 2      1.32055m', 'Fe 2      1.24854m', 'Fe 2      7637.54A']

[Program finished]

Or if you only want the values.

find_this = re.findall('Fe 2.*?([0-9].*?)\s', text)

Output:

['1.32055m', '1.24854m', '7637.54A']

[Program finished]

ANSWER TO NEW QUESTION

Here's an example of how you could achieve picking out values between 1.35 - 1.40 using a for loop and converting var into float. Now we can use conditions as in this line:

if (float_value >= 1.35) and (float_value <= 1.40):
    print(value)

if matched it prints the untouched string, keeping the ending letter.

Here's the full code: (I shortened the text for easier read)

import re


text = '''Fe 2      1.405A   33.077    0.0147
Fe 2      1.305A   33.077    0.0147
Fe 2      1.345A   33.077    0.0147
Fe 2      1.35A   33.077    0.0147
Fe 2      1.35623A   33.077    0.0147
Fe 2      1.40A   33.077    0.0147
Fe 2      1.37A   33.077    0.0147
Fe 2      1.41A   33.077    0.0147'''


find_this = re.findall('Fe 2.*?([0-9].*?)\s', text)

for value in find_this:
    del_letters = re.sub('[A-Za-z]', '', value)
    float_value = float(del_letters)
    if (float_value >= 1.35) and (float_value <= 1.40):
        print(value)

Output:

1.35A
1.35623A
1.40A
1.37A