Question 108976 in Json Question posted in
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Json – Create a hash of arrays from CSV with jq

I have the following CSV (truncated):

"adfebb","a-f-A-M-F-R-Z","95-00123","C560","USAF"
"ae0133","a-f-A-M-F-R-Z","97-00102","C560","USAF"

I need the following JSON:

{
    "adfebb":["a-f-A-M-F-R-Z","95-00123","C560","USAF"],
    "ae0133":["a-f-A-M-F-R-Z","97-00102","C560","USAF"]
}

I have been tinkering with jq and came close but I haven’t managed to get it just right. What I currently have is:

jq -R '
    inputs
    | . / "n"
    | (.[] | select(length > 0) | . / ",") as $fields
    | [$fields[1], $fields[2], $fields[3], $fields[4]] as $aircraft
    | {($fields[0]): $aircraft}
    
' >outfile.json

That produces

{
    "adfebb":["a-f-A-M-F-R-Z","95-00123","C560","USAF"]
}
{
    "ae0133":["a-f-A-M-F-R-Z","97-00102","C560","USAF"]
}

(Note the missing comma)…

I’m clearly missing something but I’m at the end of my wits…

Tags:

2

Answers


  1. 0

    I’m never sure if this is the simplest way, but I would write

    jq -R '[split(",")[] | fromjson] |
       [{key: .[0], value: .[1:]}] |
       from_entries' tmp.csv | jq -s 'add'

    An explanation…

    The first part of the filter produces a list of strings for each row. (It assumes you can treat a row as a comma-separated stream of JSON strings; jq isn’t really designed to parse CSV files.)

    $ jq -Rc '[split(",")[]|fromjson]' tmp.csv
["adfebb","a-f-A-M-F-R-Z","95-00123","C560","USAF"]
["ae0133","a-f-A-M-F-R-Z","97-00102","C560","USAF"]

    The second part of the filter creates a list of objects with key and value fields, using the first element of a list as the key and the remaining elements of a list as the value.

    $ jq -Rc '[split(",")[]|fromjson] | [{key: .[0], value: .[1:]}]' tmp.csv
[{"key":"adfebb","value":["a-f-A-M-F-R-Z","95-00123","C560","USAF"]}]
[{"key":"ae0133","value":["a-f-A-M-F-R-Z","97-00102","C560","USAF"]}]

    These lists are designed to be processed by from_entries to create the desired JSON objects.

    % jq -Rc '[split(",")[]|fromjson] | [{key: .[0], value: .[1:]}] | from_entries' tmp.csv
{"adfebb":["a-f-A-M-F-R-Z","95-00123","C560","USAF"]}
{"ae0133":["a-f-A-M-F-R-Z","97-00102","C560","USAF"]}

    The second jq command reads the objects into a single array, then "sums" them to create a single object with two keys.

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  2. 0

    With . / "," you are splitting at any occurring comma, regardless of it actually separating the columns, or being part of a column value. If you can assert that the latter won’t happen (data never contains commas), here’s an approach using reduce to successively build up your target object:

    jq -nR 'reduce (inputs / "," | map(fromjson)) as $i ({}; .[$i[0]] = $i[1:])'

    {
  "adfebb": [
    "a-f-A-M-F-R-Z",
    "95-00123",
    "C560",
    "USAF"
  ],
  "ae0133": [
    "a-f-A-M-F-R-Z",
    "97-00102",
    "C560",
    "USAF"
  ]
}
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