Splitting a list of dictionaries into several lists of dictionaries

Question

I\'ve been whacking away at this for a while to no avail... Any help would be greatly appreciated.

I have:

[{\'event\': 0, \'voltage\': 1, \'time\':         


        

Answer 1

I think what you really want is to filter them:

elist = [{'event': 0, 'voltage': 1, 'time': 0},
{'event': 0, 'voltage': 2, 'time': 1},
{'event': 1, 'voltage': 1, 'time': 2},
{'event': 1, 'voltage': 2, 'time': 3},
{'event': 2, 'voltage': 1, 'time': 4},
{'event': 2, 'voltage': 2, 'time': 5}]


from itertools import ifilter

def get_events(elist, n):
    return ifilter( lambda d: d['event'] == n , elist)

for e in get_events(elist,0):
    print e

this solution will not create additional structures. (think in case of HUGE event list)

Another very nice solution is to use groupby:

from itertools import groupby
from operator import itemgetter
for group in groupby(elist, itemgetter('event')):
    id, event_list = group
    for e in event_list:
        print e

{'time': 0, 'event': 0, 'voltage': 1}
{'time': 1, 'event': 0, 'voltage': 2}
{'time': 2, 'event': 1, 'voltage': 1}
{'time': 3, 'event': 1, 'voltage': 2}
{'time': 4, 'event': 2, 'voltage': 1}
{'time': 5, 'event': 2, 'voltage': 2}