Iterate over multiple lines

Question

I have a large text file i.e. pre.txt and I have want to read feat_left points over multiple lines using python. Here is the snapshot of the text file.

{
  "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
      ]
    },

your file is `json`: you don't want to parse it line by line, use `json.load()` to get the corresponding python structure. — Jean-François Fabre, Feb 20 '17 at 12:42
Do you want to read the file in blocks? What is your actual question? — Elodin, Feb 20 '17 at 12:45
could you please provide a snippet to read feat_left @Jean-FrançoisFabre — cpwah, Feb 20 '17 at 12:45
not reopening, but this ain't a duplicate of the mentionned question. It's more a duplicate of "how to read json file"... — Jean-François Fabre, Feb 20 '17 at 12:58
unfortunately, the starting key and values and skipped, can you please explain reason. @Jean-FrançoisFabre — cpwah, Feb 20 '17 at 15:38

Rahul K P · Accepted Answer · 2017-02-20T13:21:17.947

3

Read the json and iterate like this,

import json
data = json.load(open('file_name.json'))
for val in data['outputs'].values():
     print(val['feat_left'])

Result will be like this,

[-0.7765399217605591, -1.690917730331421]
[2.369331121444702, -1.1544183492660522]
[1.8996189832687378, -1.3713303804397583]

Edit You can use like this for image path,

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

And it will give liek this

('/home/119306609.jpg', [-0.7765399217605591, -1.690917730331421])
('/home/113267806.jpg', [2.369331121444702, -1.1544183492660522])
('/home/115061965.jpg', [1.8996189832687378, -1.3713303804397583])

edited Feb 20 '17 at 13:21

answered Feb 20 '17 at 12:48

Rahul K P

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2

providing the code to load the `json` file as well will make that a decent answer (also make it python 3 compliant) – Jean-François Fabre Feb 20 '17 at 12:49
I am not sure about duplication part? @Jean-FrançoisFabre – cpwah Feb 20 '17 at 12:55
?? anyway: post edited. Hey who upvoted before me ? :) – Jean-François Fabre Feb 20 '17 at 12:56
1

@Jean-FrançoisFabre Thank you :) – Rahul K P Feb 20 '17 at 12:57
is it possible to read "/home/119306609.jpg" for every outputs? @RahulKP – cpwah Feb 20 '17 at 13:16
1

Yeah, `data['outputs'].items()` will give `key` and `values`, So the `key` will be you image path. Answer updated. – Rahul K P Feb 20 '17 at 13:18
can you please check if it is duplication, I doubt that? was extremely considering it as text file.@RahulKP – cpwah Feb 20 '17 at 13:26
As we are iterating through the dictionary duplication is not possible. And i didn't read from any file. – Rahul K P Feb 20 '17 at 13:28
unfortunately, the starting key and values and skipped, I am trying to find the bug. @RahulKP – cpwah Feb 20 '17 at 14:31
Let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/136168/discussion-between-cpwah-and-rahul-k-p). – cpwah Feb 20 '17 at 15:32

Iterate over multiple lines

1 Answers1