Python - read json file

Question

I am trying to read the JSON file in python and it is successfully however some top values are skipped. I am trying to debug the reason. Here is the the code.

data = json.load(open('pre.txt'))

for key,val in data['outputs'].items():
    print key
    print data['outputs'][key]['feat_left']

EDIT Here is the snapshot the file. I want to read key and feat_left for outputs

{
  "outputs": {
    "/home/113267806.jpg": {
      "feat_left": [
        2.369331121444702, 
        -1.1544183492660522
      ], 
      "feat_right": [
        2.2432730197906494, 
        -0.896904468536377
      ]
    }, 
    "/home/115061965.jpg": {
      "feat_left": [
        1.8996189832687378, 
        -1.3713303804397583
      ], 
      "feat_right": [
        1.908974051475525, 
        -1.4422794580459595
      ]
    }, 
    "/home/119306609.jpg": {
      "feat_left": [
        -0.7765399217605591, 
        -1.690917730331421
      ], 
      "feat_right": [
        -1.1964678764343262, 
        -1.9359161853790283
      ]
    }
  }
 }

P.S: Thanks to Rahul K P for the code

please provide a minimal reproducible example, that shouldn't be too hard, and don't link to external file. — Jean-François Fabre
– Jean-François Fabre ♦, Commented Feb 20, 2017 at 16:48
Can you make a small example json string and post it here? We can't log into your dropbox. — tdelaney
– tdelaney, Commented Feb 20, 2017 at 16:49
Pls define the exptected output what you await. At the moment, you print the keys and the array that is stored below the key "feat_left". Also, you can output "feat_left" by using val["feat_leaft"] and val["feat_right"] because the object containing the "feat"-arrays will be converted to value by using the shown for loop. — Supahupe
– Supahupe, Commented Feb 20, 2017 at 16:51
I want to /home/113267806.jpg and feat_left @Supahupe for outputs — cpwah
– cpwah, Commented Feb 20, 2017 at 16:55
113267806.jpg is in the output. dict is unordered, so it won't appear in the same position as in the original json, but it is there. — tdelaney
– tdelaney, Commented Feb 20, 2017 at 17:01

Hossein · Accepted Answer · 2017-02-20 16:59:20Z

2

No top values are skipped. There are 45875 items in your data['output'] object. Try the following code:

len(data['outputs'].items())

And there are exactly 45875 items in your JSON file. Just note that JSON object is an unordered collection in python, like dict.

answered Feb 20, 2017 at 16:59

Hossein

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1 Comment

cpwah Over a year ago

the answer just kill me, as I was expecting it to be an ordered list. Thanks. @Hossein

aidanmelen · Accepted Answer · 2017-02-20 17:00:25Z

2

i think you want:

for key, val in data['outputs'].items():
    if 'feat_left' in val:
        print key, data['outputs'][key]['feat_left']

answered Feb 20, 2017 at 17:00

aidanmelen

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3 Comments

Supahupe Over a year ago

This is a better solution than mine above - didnt do python for some weeks

cpwah Over a year ago

I think Hossein is the one I am looking for. There is no problem with the code. Just note that JSON object is an unordered collection in python, like dict.

aidanmelen Over a year ago

If you need ordered dictionary keys, I would recommend using a collections.OrderedDict

Supahupe · Accepted Answer · 2017-02-20 17:00:05Z

If you just want to print the content of the file by using a for-loop, you can try like this:

data = json.load(open('pre.txt')
for key,val in data['outputs'].items():
      print key
      print val[0] #this will print the array and its values below "feat_left", if the json is consistent

A more robust solution could look like this:

data = json.load(open('pre.txt')
for key,val in data['outputs'].items():
      print key
      for feat_key, feat_val in val.items():
            if feat_key == 'feat_left':
                 print feat_val

Code is untested, give it a try.

Andrea D'Urso · Accepted Answer · 2017-02-20 17:43:31Z

0

Try this:

for key, val in data['outputs'].items():
    print key, val['feat_left'] 
#output /home/119306609.jpg [-0.7765399217605591, -1.690917730331421]

This get every key and element within 'feat_left' Then you can display in the page however you like

answered Feb 20, 2017 at 17:43

Andrea D'Urso

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