将double for循环转换为列表理解

Question

我有以下json对象：

{u'trailerAvailable': False, u'number': 10, u'watched': False, u'starringCast': u'Jan Fedder,Anja Nejarri', u'genres': [u'Krimi'], u'title': u'S\xfc\xdfes Jenseits', u'ancestorTitles': [{u'contentType': u'SERIES', u'titleId': u'B00ILY1FWE', u'title': u'Gro\xdfstadtrevier'}, {u'contentType': u'SEASON', u'number': 19, u'titleId': u'B00ILZTVXI', u'title': u'Gro\xdfstadtrevier - Staffel 19'}], u'restricted': False, u'synopsis': u"Dirk Matthies und Katja Metz erhalten einen entscheidenden Tipp, um endlich Hannes Rogolski alias 'die Ziege' zu fassen. Allerdings bringt der schwer kranke Informant dadurch seine Lebensgef\xe4hrtin Hilde in Gefahr.", u'titleId': u'B00ILZOQWE', u'watchCompleted': False, u'creditsStartTimeMillis': 2836000, u'customerReviewsCollectionIncluded': True, u'contentType': u'EPISODE', u'childTitles': [], u'studioOrNetwork': u'ARD', u'amazonRating': {u'count': 0, u'rating': 0.0}, u'watchedPositionMillis': {u'valueMillis': 0}, u'listInfo': [], u'previewAvailable': False, u'subtitles': {u'content': {u'languages': []}, u'preview': {u'languages': []}, u'trailer': {u'languages': []}}, u'restrictions': [], u'regulatoryRating': u'12', u'releaseOrFirstAiringDate': {u'valueFormatted': u'2005-03-21T00:00:00', u'valueDate': 1111363200000000}, u'hasSubtitles': False, u'formats': [{u'hasMobileTrailerEncode': False, u'videoAspectRatio': 0.0, u'offers': [{u'asin': u'B0043YVHMY', u'offerType': u'SUBSCRIPTION', u'buyable': False}, {u'asin': u'B00ILZOQWE', u'price': {u'valueFormatted': u'1,49\u20ac', u'valueLong': 149.0}, u'offerType': u'PURCHASE', u'purchaseButtonText': u'Buy episode - 1,49\u20ac', u'buyable': True}, {u'rentalExpiryTermFromPurchase': {u'valueMillis': 2592000000, u'valueFormatted': u'30 days to start watching'}, u'asin': u'B00QVECS4U', u'rentalExpiryTermFromStart': {u'valueMillis': 86400000, u'valueFormatted': u'24 hours to complete watching'}, u'offerType': u'RENTAL', u'buyable': False}], u'audioFormatTypes': [u'STEREO'], u'videoFormatType': u'SD', u'hasMobileEncode': True, u'images': [{u'heightPx': 0, u'widthPx': 0, u'type': u'COVER_ART_TV', u'uri': u'http://ecx.images-amazon.com/images/I/51a8c53GcjL._UR667,500_V1_PJStripe-Prime-Only-500px,TopLeft,0,0_.jpg'}, {u'heightPx': 0, u'widthPx': 0, u'type': u'COVER_ART_TV', u'uri': u'http://ecx.images-amazon.com/images/I/51a8c53GcjL._UR667,500_V1_PJStripe-Prime-Only-500px,TopLeft,0,0_.jpg'}], u'hasTrailerEncode': False, u'hasEncode': True}, {u'hasMobileTrailerEncode': False, u'videoAspectRatio': 0.0, u'offers': [{u'asin': u'B0043YVHMY', u'offerType': u'SUBSCRIPTION', u'buyable': False}, {u'asin': u'B00ILZOR9Q', u'offerType': u'PURCHASE', u'buyable': False}, {u'rentalExpiryTermFromPurchase': {u'valueMillis': 2592000000, u'valueFormatted': u'30 days to start watching'}, u'asin': u'B00QVFSN0W', u'rentalExpiryTermFromStart': {u'valueMillis': 86400000, u'valueFormatted': u'24 hours to complete watching'}, u'offerType': u'RENTAL', u'buyable': False}], u'audioFormatTypes': [u'STEREO'], u'videoFormatType': u'HD', u'hasMobileEncode': False, u'images': [{u'heightPx': 0, u'widthPx': 0, u'type': u'COVER_ART_TV', u'uri': u'http://ecx.images-amazon.com/images/I/51a8c53GcjL._UR667,500_V1_PJStripe-Prime-Only-500px,TopLeft,0,0_.jpg'}, {u'heightPx': 0, u'widthPx': 0, u'type': u'COVER_ART_TV', u'uri': u'http://ecx.images-amazon.com/images/I/51a8c53GcjL._UR667,500_V1_PJStripe-Prime-Only-500px,TopLeft,0,0_.jpg'}], u'hasTrailerEncode': False, u'hasEncode': False}], u'customerReviewCollection': {u'customerReviews': [], u'customerReviewSummary': {u'totalReviewCount': 0, u'threeStarReviewCount': 0, u'averageOverallRating': 0.0, u'twoStarReviewCount': 0, u'fiveStarReviewCount': 0, u'oneStarReviewCount': 0, u'fourStarReviewCount': 0}}, u'runtime': {u'valueMillis': 2820000, u'valueFormatted': u'47m'}, u'contractID': u'UXSG4'}

我正在尝试通过以下方式获得所有asin ：

possible_episode_ids = []
for item in t['formats']:
    for i in item['offers']:
        possible_episode_ids.append(i['asin']) 

>>> possible_episode_ids
[u'B0043YVHMY', u'B00ILZOQWE', u'B00QVECS4U', u'B0043YVHMY', u'B00ILZOR9Q', u'B00QVFSN0W']

如何使用列表理解功能？

Answer 1

只需复制现有行：

possible_episode_ids = [
    i['asin']
    for item in t['formats']
    for i in item['offers']
]

Answer 2

尝试这个：

possible_episode_ids=[offer['asin']  for fmt in t['formats'] for offer in fmt['offers']]

Answer 3

possible_episode_ids = [j['asin'] for i in t['formats'] for j in i['offers']]