CODEWITHSUNDEEP
pythonarraysjsonpython-2.7
SCO
SCO

Reputation: 1932

How to modify a Python JSON objects array

Let's assume the following :

sp_sample=[{"t":1434946093036,"v":54.0},{"t":1434946095013,"v":53.0},{"t":1434946096823,"v":52.0}

I wish I could get the following result :

sp_sample=[{"t":1434946093036,"v":5400.0},{"t":1434946095013,"v":5300.0},{"t":1434946096823,"v":5200.0}

In other words, I wish I could iterate through the array and multiple v by a 100 factor.

The following only performs the multiplication on the first item, ie yields 54000 :

for i, a in enumerate(sp_sample):
    a[i]['v'] =  a[i]['v'] * 100

The sp_sample is of type tuple. Using the following yields the whole array, which is not what I expect :

print sp_sample[0]

Also, tried printing sp_sample :

print sp_sample

Which returns the following (replaced the ....... for brevity) :

([{'t': 1434946093036, 'v': 54.0}, {'t': 1434946095013, 'v': 53.0}, {'t': 1434946096823, 'v': 52.0}, {'t': 1434946098612, 'v': 52.0}, {'t': 1434946100400, 'v': 51.0}, {'t': 1434946102372, 'v': 49.0},........, {'t': 1434947987823, 'v': 15.0}, {'t': 1434947989851, 'v': 12.0}, {'t': 1434947991899, 'v': 10.0}, {'t': 1434947993744, 'v': 5.0}, {'t': 1434947995599, 'v': 0.0}, {'t': 1434947997455, 'v': 0.0}, {'t': 1434947999494, 'v': 0.0}, {'t': 1434948001542, 'v': 0.0}, {'t': 1434948003417, 'v': 0.0}, {'t': 1434948005264, 'v': 0.0}, {'t': 1434948007120, 'v': 0.0}],)

print type(sp_sample) returns :

Upvotes: 2

Views: 2534

Answers (1)

mhawke
mhawke

Reputation: 87064

Simply iterate over the list and update the dictionaries as you go:

sp_sample = [{"t":1434946093036,"v":54.0},{"t":1434946095013,"v":53.0},{"t":1434946096823,"v":52.0}]

for d in sp_sample:
    d['v'] *= 100

>>> print(sp_sample)
[{'t': 1434946093036, 'v': 5400.0}, {'t': 1434946095013, 'v': 5300.0}, {'t': 1434946096823, 'v': 5200.0}]

This will bind in turn each dictionary in list (tuple?) sp_sample to d, which you then update in place. You do not need to use enumerate().

Note that you really need to multiply by 100, not 10000, to achieve the output that you have shown.

Update

sp_sample is actually a tuple with a list of dictionaries as its only item. So you need to access the list in the tuple like this:

sp_sample = ([{"t":1434946093036,"v":54.0},{"t":1434946095013,"v":53.0},{"t":1434946096823,"v":52.0}],)

for d in sp_sample[0]:    # N.B. access first item of tuple
    d['v'] *= 100
>>> print(sp_sample)
[{'t': 1434946093036, 'v': 5400.0}, {'t': 1434946095013, 'v': 5300.0}, {'t': 1434946096823, 'v': 5200.0}]

Or, since the tuple contains only a single item you could just get rid of the tuple by:

sp_sample = sp_sample[0]
for d in sp_sample:
    d['v'] *= 100

Upvotes: 8

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