How to Iterate Tuples though OrderedDict-CodePudding

I have a list of OrderedDict as follows:

    power = [OrderedDict([('i', '1'), ('p', '-9.11')]), OrderedDict([('i', '2'), ('p', '-9.11')]), OrderedDict([('i', '3'), ('p', '-9.1')]), OrderedDict([('i', '4'), ('p', '-9.1')]), OrderedDict([('i', '5'), ('p', '-9.1')]), OrderedDict([('i', '6'), ('p', '-9.1')]), OrderedDict([('i', '7'), ('p', '-9.09')]), OrderedDict([('i', '8'), ('p', '-9.09')]), OrderedDict([('i', '9'), ('p', '-9.09')]), OrderedDict([('i', '10'), ('p', '-9.09')]), OrderedDict([('i', '11'), ('p', '-9.08')]), OrderedDict([('i', '12')]]

I want the get the 'i' number such as 1,2,3 and also the 'p' value '-9.11', '-9.1' .. I have tried

for i,j in power:
    print(i,":", j)

but it returns i:p Any idea how to execute that?

CodePudding user response：

You could try:

for i, j in (d.values() for d in power):
    print(f'{i} : {j}')

Assuming each OrederedDict in power has a length of 2.

CodePudding user response：

There are no tuples in your OrderedDict. When you do call OrderedDict(iterable) (e.g. in your case the iterable is a list), it expects that each element of iterable gives you a key-value pair. So in your case, each element of the list is a tuple, and the first element of that tuple is the key, the second item is the value to set in the OrderedDict.

When you do for item in power, each item is an OrderedDict. When you try to unpack it in that same line with for i, j in power, the OrderedDict called item gets unpacked into the variables i and j. When you unpack a dict, you get its keys, so the variable i gets the first key (which is the string "i"), and the variable p gets the second key (which is the string "p"). You could unpack the values using ssp's answer, but I suggest you should actually access the keys of the dict.

Once you have item, you can simply access its keys using item[key]. So do:

for item in power:
    print(item["i"], ":", item["p"])

If you want to create a new dictionary where the values of the i key are keys and the values of the p key are values, do:

d = dict()
for item in power:
    key = item["i"]
    value = item["p"]
    d[key] = value

Or, as a dict comprehension:

d = {item["i"]: item["p"] for item in power}

Which gives:

{'1': '-9.11',
 '2': '-9.11',
 '3': '-9.1',
 '4': '-9.1',
 '5': '-9.1',
 '6': '-9.1',
 '7': '-9.09',
 '8': '-9.09',
 '9': '-9.09',
 '10': '-9.09',
 '11': '-9.08'}

If you want the keys to be integers and the values to be floats, explicitly convert them:

d = {int(item["i"]): float(item["p"]) for item in power}