CODEWITHSUNDEEP
pythonarrayslistdictionary
trouselife
trouselife

Reputation: 969

Create a dictionary that is associated with lists and update this through a loop

I am using python2.7. I have a file which contains a chromosomal location and an experiment ID. I have got this information stored at the moment in two lists:

unique_locations - containing a single value for each location
location_exp - containing lists of [location, experiment]

The reason I have not used a dictionary is that there are multiple locations found in multiple experiments - i.e this is a many-many relationship.

I would like to find out on how many experiments each location is found. I.e get a list like:

[
    [location1, [experiment1, experiment2, experiment3]], 
    [location2, [experiment2, experiment3, experiment4]]
                                                             ]

etc.

As the lengths of the lists are different I have failed using an enumerate(list) loop on either lists. I did try:

location_experiment_sorted = []
for i, item in enumerate(unique_experiment):
    location = item[0]
    exp = item[1]
    if location not in location_experiment_sorted:
        location_experiment_sorted.append([location, exp])
    else:
        location_experiment_sorted[i].append(exp)

Amongst other things. I have also tried using a dictionary which relates to a list of multiple experiments. Can anyone point me in the right direction?

Upvotes: 2

Views: 77

Answers (4)

Iron Fist
Iron Fist

Reputation: 10951

Here is another working example, using built-in dict and groupby from itertools:

>>> from itertools import groupby
>>> d = {}
>>> location_exp = [
    ("location1", "experiment1"),
    ("location1", "experiment2"),
    ("location1", "experiment3"),
    ("location2", "experiment2"),
    ("location2", "experiment3"),
    ("location2", "experiment4")
]
>>> for k,v in groupby(location_exp, itemgetter(0)):
        d.setdefault(k,[])
        d[k].extend([loc for _, loc in v])


[]
[]
>>> d
{'location2': ['experiment2', 'experiment3', 'experiment4'], 'location1': ['experiment1', 'experiment2', 'experiment3']}
>>> 
>>> d2 = {}
>>> location_exp2 = [
    ("location1", "experiment1"),
    ("location2", "experiment2"),
    ("location3", "experiment3"),
    ("location1", "experiment2"),
    ("location2", "experiment3"),
    ("location3", "experiment4")
]
>>> for k,v in groupby(location_exp2, itemgetter(0)):
        d2.setdefault(k,[])
        d2[k].extend([loc for _, loc in v])


[]
[]
[]
['experiment1']
['experiment2']
['experiment3']
>>> d2
{'location2': ['experiment2', 'experiment3'], 'location1': ['experiment1', 'experiment2'], 'location3': ['experiment3', 'experiment4']}

Upvotes: 1

janbrohl
janbrohl

Reputation: 2656

If I do understand you correctly (if locations can be used as dict keys)

you could do:

location_experiments={}
for location, experiment in location_exp:
    location_experiments.setdefault(location,[]).append(experiment)

Upvotes: 2

petrs
petrs

Reputation: 405

Try defaultdict, ie:

from collections import defaultdict

unique_locations = ["location1", "location2"]
location_exp = [
    ("location1", "experiment1"),
    ("location1", "experiment2"),
    ("location1", "experiment3"),
    ("location2", "experiment2"),
    ("location2", "experiment3"),
    ("location2", "experiment4")
]

location_experiment_dict = defaultdict(list)
for location, exp in location_exp:
    location_experiment_dict[location].append(exp)

print(location_experiment_dict)

will print-out:

defaultdict(<type 'list'>, {
    'location2': ['experiment2', 'experiment3', 'experiment4'],
    'location1': ['experiment1', 'experiment2', 'experiment3']
})

Upvotes: 2

Keef Baker
Keef Baker

Reputation: 641

I haven't run this, so apologies if it fails. if you say it's a list of lists like [ [location, experiment], [location, experiment] ] then:

locationList = {}
for item in unique_experiment:
    location = item[0]
    exp = item[1]
    if location not in locationList:
        locationList[location] = []
        locationList[location].append(exp)
    else:
        locationList[location].append(exp)

Upvotes: 1

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