python - 根据分组变量从文件加载列表列表？

Question

如果我有文件:

A pgm1
A pgm2
A pgm3
Z pgm4
Z pgm5
C pgm6
C pgm7
C pgm8
C pgm9

如何创建列表:

[['pgm1','pgm2','pgm3'],['pgm4','pgm5'],['pgm6','pgm7','pgm8','pgm9']]

我需要保留加载文件中的原始顺序。所以 [pgm4, pgm5] 必须是第二个子列表。

我的偏好是，当分组变量与前一个变量发生变化时(即“A、Z、C”)，会触发新的子列表。但如果分组变量必须是连续的，即“1,2,3”，我可以接受。

(这是为了支持同时运行每个子列表中的程序，但要等待所有上游程序完成才能继续下一个列表。)

我在 RHEL 2.6.32 上使用 Python 2.6.6

Answer 1

只需使用 collections.defaultdict() 。

代码:

import collections
d = collections.defaultdict(list)

infile = 'filename'
with open(infile) as f:
    a = [i.strip() for i in f]

a = [i.split() for i in a]

for key, value in a:
    d[key].append(value)

l = list(d.values())

演示:

>>> import collections
>>> d = collections.defaultdict(list)

>>> infile = 'filename'
>>> with open(infile) as f:
...     a = [i.strip() for i in f]

>>> a = [i.split() for i in a]
>>> a
[['A', 'pgm1'], ['A', 'pgm2'], ['A', 'pgm3'], ['Z', 'pgm4'], ['Z', 'pgm5'], ['C', 'pgm6'], ['C', 'pgm7'], ['C', 'pgm8'], ['C', 'pgm9']]

>>> for key, value in a:
...     d[key].append(value)

>>> d
defaultdict(<class 'list'>, {'A': ['pgm1', 'pgm2', 'pgm3'], 'C': ['pgm6', 'pgm7', 'pgm8', 'pgm9'], 'Z': ['pgm4', 'pgm5']})

>>> d.values()
dict_values([['pgm1', 'pgm2', 'pgm3'], ['pgm6', 'pgm7', 'pgm8', 'pgm9'], ['pgm4', 'pgm5']])

>>> list(d.values())
[['pgm1', 'pgm2', 'pgm3'], ['pgm6', 'pgm7', 'pgm8', 'pgm9'], ['pgm4', 'pgm5']]
>>> 

<小时/>

下面的代码与上面的代码执行相同的操作，但保持顺序:

infile = 'filename'
with open(infile) as f:
    a = [i.strip() for i in f]

a = [i.split() for i in a]

def orderset(seq):
    seen = set()
    seen_add = seen.add
    return [ x for x in seq if not (x in seen or seen_add(x))]

l = []
for i in orderset([i[0] for i in a]):
    l.append([j[1] for j in a if j[0] == i])