Yesterday’s task was opening a very large JSON data file.

JSON is a serialized text format. It has only one line so we can’t display the first or last lines with head or tail. But, it’s still text, so we You can give it a quick look with cat

cat FILE

and just stare at words on the screen. Not very useful, let’s see the first 1000 characters

grep -o '^.\{1000\}' FILE

We can see the beginning part but it really isn’t saying much. What we want to see is the structure of the file, the keys of the key-value pairs.

We can do that with python

import json

jsf="" # the json file name
with open (jsf) as f:
    data=json.load(f)
    print(data.keys)

For the nested key-value pairs, we can look inside the same way.

For example, suppose we have a property called “summary” whose value is {"key1":value1,"key2":value2,...} within this structure. This is how to display the keys:

import json

jsf="" # the json file name
with open (jsf) as f:
    data=json.load(f)
    print(data['summary'].keys)