Extract a specific value from a text file

Question

Total newbie here. I have a .txt file and I want to extract a specific value....

The .txt file is structure like this:

{
"animal": "Cat",
"colour": "golden",
...and so on
}

I can open and print he whole file ...... but how do I print just the "animal" plus its value which in this case is "cat" bit?

The file itself has hundreds of entries and I want to know how to extract and print all the "animal"s for example.

Any help greatly appreciated.

Answer 1

The text file you provided seems to be a dictionary itself. So I suggest you use ast module in order to change the format of this text file from string to a valid dictionary and then call animal key from this dictionary:

import ast
with open("myText.txt") as f:
  myFile = f.read()
  myDict = ast.literal_eval(myFile)
  print(myDict["animal"])

Output

Cat

Note that, I have named the text file myText.txt. It might be different in your machine, so change it to the valid path of your text file.

Answer 2

If you have "animal": ... in separated lines then you could read line by line and check if "animal" in line and later split(":") and remove " ", to get only text Cat, etc.

Minimal working example. I use io only to simulate file but you should use open()

text = '''{
"animal": "Cat",
"colour": "golden",
#...and so on
}
{
"animal": "Dog",
"colour": "black",
#...and so on
}
'''

import io

#f = open(filename)
f = io.StringIO(text)

for line in f:
    line = line.strip(' \n,')  # remove spaces, tabs but also `,`
    
    #if 'animal' in line:            # it get `animal` in any place - ie. 'small animals'
    if line.startswith('"animal"'):  # it get only "animal" (with `" "`) at the beginning of line
        parts = line.split(':')
        print(parts[1].strip(' "'))

Result:

Cat
Dog

But this way you get only value for animal and you would need much more code to get all values in records - so it would need more code to display colour only for Cat.

---

But your data looks similar to JSON so maybe you have all records inside [ ] and with , between records - like

[
{
"animal": "Cat",
"colour": "golden",
#...and so on
},
{
"animal": "Dog",
"colour": "black",
#...and so on
}
]

and then you could use module json to get it as list with dictionares and use for-loop to check every record and get animal. And it could be simpler to get other values - ie. get colour only for Cat.

text = '''[
{
"animal": "Cat",
"colour": "golden"
},
{
"animal": "Dog",
"colour": "black"
}
]
'''

import io
import json

#f = open(filename)
f = io.StringIO(text)

data = json.load(f)

for record in data:
    print(record['animal'])
    if record['animal'] == 'Cat':
        print('  colour:', record['colour'])

Result:

Cat
  colour: golden
Dog

---

If you create this file with records then you could use module json to write data.