Assembly Line

Numbers

From the manual

jq supports the same set of datatypes as JSON - numbers, strings, booleans, arrays, objects (which in JSON-speak are hashes with only string keys), and "null".

Let's focus on numbers.

Numbers and numeric operators

All numbers, whether integers or otherwise, are IEEE754 double precision floating point numbers. This limits us to 53 bits of precision.

The usual operators are available to use with numbers:

• arithmetic: +, -, *, /, %

• comparison: ==, !=, <, <=, >=, >

• standard math functions

  For one-input functions, pipe the value into the function

  $ jq -n '(1 | atan) * 4'
  3.141592653589793
  

  For two-input functions, the functions will ignore input and expect the inputs as parameters (recall parameters are separated by semicolons)

  $ jq -n 'pow(2; 10)'
  1024
  

  Semi-colon is the separator for function arguments, not comma.

Other jq expressions

To solve the exercise, you will need to know about conditional expressions.

Conditional Expressions

jq uses an if-then-else expression for conditional expressions. As an expression, it is placed in a pipeline.

Then syntax is: if CONDITION then TRUE_EXPR else FALSE_EXPR end.

The else clause is optional in jq v1.7, but it is required in jq v1.6.

42 | if . < 33 then "small" else "larger" end
# => "larger"

Additional conditions use elif

42 | if . < 33 then "small"
     elif . < 67 then "medium"
     else "large"
     end
# => "medium"