[Purdue-pm] reading JSON with different programming languages

derrick derrick at csociety.org
Mon Apr 28 10:35:51 PDT 2014

Wow, I think I really messed this one up!

I was working on the first part of the challenge problem this weekend 
and had a huge brain fart. I need your help to getting this sample json 
file cleaned up.

In our last meeting we learned about the JSON file format. I created the 
sample json file I wanted to use for the first part of the challenge, 
but I accidentally mixed up some of values while I was writing the file. 
To make things worst, my favorite text editor mysteriously now opens 
json files in read only mode, so I can't just go in and fix it by hand 
(ugh, technology).

I uploaded the file here:

While I sort things out with my system, if you have a bit of extra time, 
can you write a program that will do the following:

1) Read and Parse the JSON file.

Read the json file into memory and parse it into data structures that 
best fit the programming language you are using. There are 6 data types 
you need to worry about:

Primitive Types:
* null
* booleans
* strings
* numbers

Structured Types:
* arrays
* objects

More information about the json file format can be found here:

The file represents a dictionary, or hash table, or associative array.

There is probably a library available in your programming language, you 
can use to quickly read and parse the file. The json.org website has a 
list of some libraries for popular programming languages.

After parsing the file into your language's data structures, you should 
print the values stored in the data structures to stdout or another file 
to make sure you are reading the data properly. don't just print the 
file after reading it.

2) Fix the JSON file and write it back to disk.

Here is where it gets tricky. Even though the json file was 
syntactically correct, I made some mistakes in the data that is stored 
in it. Here is a summary of what I wanted for each key in the dictionary :

* null_value should be a json NULL or None value, not a string.
* boolean_true should be a json true value, not false
* boolean_false should be a json false value, not true
* integer_number should be the integer representation of its current 
value, not the floating point representation (ie 3)
* number_examples -> "not a number" should not even be in the 
dictionary, lets remove it.
* in "array", the string "value5" should read "value4" to match "key4"

Can you write a program to make these specific changes? Don't forget to 
comment your code. If you find an interesting way of addressing elements 
inside of the structure, please highlight that in your code. For 
example, how would you find the value for "key4" in the file? If there 
were multiple dictionary keys named "key4" in the file, how could you 
make sure you were addressing the correct one?

The data in the outputted file should look something like like this:

     "null_value": null,
     "boolean_true": true,
     "boolean_false": false,
     "string": "this is my string.",
     "integer_number": 3,
     "number_examples": {
         "positive integer": 9,
         "negative integer": -1,
         "float": 2.3,
         "positive_exponent": 4.35e+58,
         "negative_exponent": 4.3508e-93
     "array": [true,null,["value3"],{"key4":"value4"}]

Note that the order of the keys (null_value, boolean_true, 
boolean_false, ...) does not matter since the pairs of a json object are 

We'll discuss how to perform these actions in the different programming 
languages people chose to use in the next meeting on May 20, 2014.


On 04/15/2014 02:30 PM, Mark Senn wrote:
> Derrick Kearney is going to prepare some JSON and the following people
> will talk and/or write about how they read it with the following
> programming languages before or at the Purdue Perl Mongers meeting on
> May 20, 2014.  Send email to markiest at purdue.edu (remove "iest" from
> the email address) with any corrections or additions to the below list.
> Mathematica    Mark Senn
> Perl           Dave Jacoby
> PHP            Chris Orr
> pro            Mark Senn
> Python         Joe Kline
> Ruby           Rick Westerman
> Mark Senn, Systems Programmer, Engineering Computer Network, Purdue University

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