CODEWITHSUNDEEP
pythonjsonpython-3.x
Oslo
Oslo

Reputation: 63

How can I call variables and strings together from a json file in Python?

I am trying to print variables and strings in a line. like [Hello! name How are you?] -> [Hello! John How are you?]

json file

#json01.json
{
"greet" : ["Hello! *name* How are you?"] # I don't know how to write this part..
}

and this is where I am..

import json

a = 'greet'
name = 'John'

with open('json01.json') as json_file:
json_dict = json.load(json_file)

if a in json_dict:
    print(json_dict[a]) # I don't know how to write this part as well..

How should I do to get the result I want?

Sorry for the poor explanation and Thank you!

Upvotes: 4

Views: 249

Answers (2)

kajakIYD
kajakIYD

Reputation: 91

In case you want to "substitute" more than only one variable into string, with pointing out explicitly what do you want to instantiate without typing many arguments in .format():

  1. Create a dictionary. Keys should be strings to be replaced in acquired string and values should be variables that will appear in place of keys.
  2. Use double asterisk ** to extract keys from namespace dictionary to "unpack" dictionary into .format() arguments list to substitute keys by values in acquired string

According to your example:

import json

a = 'greet'
name = 'John'
weight = 80
height = 190
age = 23
# 1.
namespace = {'name': name, 'age': age, 'weight': weight, 'height': height}

json_dict_all_keys = json.loads('{"greet" : "Hello! {name}, {age} years old, {height}cm, {weight}kg. How are you?"}')
json_dict_some_keys = json.loads('{"greet" : "Hello! {name}, {weight}kg. How are you?"}') 
json_dict_mixed_keys = json.loads('{"greet" : "Hello! {name}, {other} years old, {key}cm, {weight}kg. How are you?"}')
json_dict_none_of_keys = json.loads('{"greet" : "Hello! {some}, {other} years old, {key}cm, {here}kg. How are you?"}')

if a in json_dict:
    # 2.
    print(json_dict_all_keys[a].format(**namespace))  # Hello! John, 23 years old, 190cm, 80kg. How are you?
    print(json_dict_some_keys[a].format(**namespace))  # Hello! John, 80kg. How are you?
    print(json_dict_mixed_keys[a].format(**namespace))  # Raising KeyError!
    print(json_dict_none_of_keys[a].format(**namespace))  # Raising KeyError too!

As you can see, there is no requirement to use all of "keys" from namespace. But be careful - when in string you want to format appears "key" that is not included in namespace KeyError will occur.

To simplify explaination I used json.loads instead of loading json from file with json.load.

Upvotes: 0

shx2
shx2

Reputation: 64338

There are various ways to format strings in python.

Here are 3 examples:

"Hello! %s How are you?" % name
"Hello! %(name)s How are you?" % locals()
"Hello! {name} How are you?".format(name=name)

Search the web for "python string formatting", and you'll find plenty of useful stuff.

Upvotes: 5

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