创建一个与列表相关联的字典，并通过循环对其进行更新

Question

我正在使用python2.7。我有一个包含染色体位置和实验ID的文件。目前，我将此信息存储在两个列表中：

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

我没有使用字典的原因是在多个实验中发现了多个位置-即这是一个多对多的关系。

我想找出每个位置发现了多少个实验。即获取如下列表：

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

等等。

由于列表的长度不同，我在两个列表上使用枚举(列表)循环都失败了。我确实试过了：

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)

在其他事情中。我还尝试使用与多个实验列表相关的字典。谁能给我指个方向？

Answer 1

如果我理解正确(如果位置可以用作字典键)

你可以这样做：

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

Answer 2

尝试使用defaultdict，即：

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)

将打印输出：

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

Answer 3

我还没有运行过，如果失败了，很抱歉。如果你说它是一个列表，比如[ location，实验，位置，实验]，那么：

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)