Question

我正在尝试在字符串上使用ast.literal_eval，但是收到内存错误。列表是否嵌套太多或问题是什么？还有其他选择吗？

MemoryError                               Traceback (most recent call last)
<ipython-input-138-3ea9110f7dc3> in <module>()
      1 s = "[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[['Xenophrys_bairdii'],'Vulpanser_spaldingi'],'Vipera_yeltoniensis'],'Vipera_minutus'],'Vanellus_vegans'],'Vanellus_bedriagai'],'Ursus_gratiosa'],'Uroplatus_flavomaculatus'],'Trionyx_leporosum'],'Tringa_aspera'],'Trachemys_sirtalis'],'Terpsihone_varius'],'Spermophilus_hassanica'],'Siniperca_decor'],'Scolopendra_marcianus'],'Rufibrenta_montela'],'Riparia_clinatus'],'Rhinolophus_tuberculosus'],'Rhacodactylus_citrsola'],'Remiz_niloticus'],'Pterinochilus_physalus'],'Procellaria_truncatus'],'Procellaria_lutris'],'Poephagus_indica'],'Platemys_albopillosum'],'Pica_totanus'],'Pica_mexicana'],'Phrynomerus_pelagicus'],'Philothamnus_tuberculosus'],'Petrocincla_acuta'],'Pelomedusa_rusticolus'],'Pagophila_metallica'],'Pachytriton_sibiricus'],'Otis_moschata'],'Otis_franckii'],'Otis_emarginatus'],'Opheodrys_clarus'],'Mylopharyngodon_diffidens'],'Mergus_carinata'],'Meles_carbonaria'],'Mabuya_carnivorus'],'Lystrophis_siebenrocki'],'Lyrurus_tinctorius'],'Lycodon_dendrophila'],'Lutra_plathyrhychos'],'Leptopelis_plumipes'],'Leptopelis_licin'],'Leiurus_grossmani'],'Lasiodora_hipposideros'],'Larus_pulchripes'],'Kinosternon_guineti'],'Kassina_canorus'],'Hysterocrates_chukar'],'Hydrochelidon_euptilura'],'Hemitheconyx_pulchripes'],'Haplopelma_arcticus'],'Hadrurus_dominus'],'Gypaetus_schneideri'],'Glareola_leucophyllata'],'Gerrhosaurus_ruficollis'],'Geochelone_filipjevi'],'Gallinago_pallasii'],'Eutamias_multifasciata'],'Eulabeia_tinnunculus'],'Eudrornias_penelope'],'Eudramias_tadorna'],'Eschrichtius_pulchra'],'Eremophila_similis'],'Equus_fluviatilis'],'Epicrates_carinatus'],'Emydura_avosetta'],'Emberiza_japonica'],'Dyscophus_rubicola'],'Dendrelaphis_griseus'],'Cypselus_ceterus'],'Cynops_rutila'],'Cygnus_rubicola'],'Ctenosaura_sphenocercus'],'Coenobita_variabilis'],'Clemmys_caudata'],'Cervus_comicus'],'Castor_prominanus'],'Casarca_holbrooki'],'Capella_aestivus'],'Buthus_nebularia'],'Bronchocela_bicoloratum'],'Branta_ferrumequinum'],'Balaenoptera_piscator'],'Athene_musculus'],'Argynnis_versicolor'],'Arenaria_javanica'],'Anthropoides_aestivus'],'Anolis_medirostris'],'Anodonta_infrafrenata'],'Ambystoma_alcinous'],'Acanthoceros_euptilura']"
----> 2 ast.literal_eval(s)

~\Anaconda3\lib\ast.py in literal_eval(node_or_string)
     46     """
     47     if isinstance(node_or_string, str):
---> 48         node_or_string = parse(node_or_string, mode='eval')
     49     if isinstance(node_or_string, Expression):
     50         node_or_string = node_or_string.body

~\Anaconda3\lib\ast.py in parse(source, filename, mode)
     33     Equivalent to compile(source, filename, mode, PyCF_ONLY_AST).
     34     """
---> 35     return compile(source, filename, mode, PyCF_ONLY_AST)
     36 
     37 

MemoryError:

Answer 1

显然解析器在解析嵌套列表时有一些限制（在我们的示例中，但很可能也适用于其他容器）。它打破ast.literal_eval和eval（不安全），并且它们都具有相同的限制这一事实告诉我他们都使用了一些公共代码（也可能影响其他领域）。
在我的情况下，它是 92 （ 93 打破它），但是因为快速 Python 源代码搜索没有显示任何相关内容（如常量，#define或smth类似），此值可能与我的环境（机器，堆栈， OS ， Python 版本等）。
请注意，嵌套列表可以具有更高的嵌套级别（受[Python]: sys.getrecursionlimit()限制 - 对于我尝试创建 999 （或更高）级嵌套列表，已提出RecursionError）。

无论如何，作为替代方案，我使用[Python]: json - JSON encoder and decoder，它有效（通过一些处理）。请注意，尽管此方法适用于您的场景，但它并不完美;例如：如果其中一个字符串包含引号（简单或双重），则将不再起作用。

code.py ：

import sys import ast import json import traceback LIST_NESTING_LIMIT = 92 def generate_nested_list(count): if count <= 0: return None ret = ["0"] for i in range(1, count): ret = [ret, "{:d}".format(i)] return ret def test_parse_nested_list(count, parse_func): nested_list_str = str(generate_nested_list(count)) try: parsed = parse_func(nested_list_str) except: traceback.print_exc(limit=0) else: return parsed def json_loads_wrapper(nested_list_str): return json.loads(nested_list_str.replace("'", "\"")) def main(): for func in (ast.literal_eval, eval, json_loads_wrapper): for i in (LIST_NESTING_LIMIT, LIST_NESTING_LIMIT + 1): print("\nTrying to parse a {:d} level nested list using '{:s}':".format(i, func.__name__)) result = test_parse_nested_list(i, func) if result is not None: print(result) print("\nOriginal list:") s = "[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[['Xenophrys_bairdii'],'Vulpanser_spaldingi'],'Vipera_yeltoniensis'],'Vipera_minutus'],'Vanellus_vegans'],'Vanellus_bedriagai'],'Ursus_gratiosa'],'Uroplatus_flavomaculatus'],'Trionyx_leporosum'],'Tringa_aspera'],'Trachemys_sirtalis'],'Terpsihone_varius'],'Spermophilus_hassanica'],'Siniperca_decor'],'Scolopendra_marcianus'],'Rufibrenta_montela'],'Riparia_clinatus'],'Rhinolophus_tuberculosus'],'Rhacodactylus_citrsola'],'Remiz_niloticus'],'Pterinochilus_physalus'],'Procellaria_truncatus'],'Procellaria_lutris'],'Poephagus_indica'],'Platemys_albopillosum'],'Pica_totanus'],'Pica_mexicana'],'Phrynomerus_pelagicus'],'Philothamnus_tuberculosus'],'Petrocincla_acuta'],'Pelomedusa_rusticolus'],'Pagophila_metallica'],'Pachytriton_sibiricus'],'Otis_moschata'],'Otis_franckii'],'Otis_emarginatus'],'Opheodrys_clarus'],'Mylopharyngodon_diffidens'],'Mergus_carinata'],'Meles_carbonaria'],'Mabuya_carnivorus'],'Lystrophis_siebenrocki'],'Lyrurus_tinctorius'],'Lycodon_dendrophila'],'Lutra_plathyrhychos'],'Leptopelis_plumipes'],'Leptopelis_licin'],'Leiurus_grossmani'],'Lasiodora_hipposideros'],'Larus_pulchripes'],'Kinosternon_guineti'],'Kassina_canorus'],'Hysterocrates_chukar'],'Hydrochelidon_euptilura'],'Hemitheconyx_pulchripes'],'Haplopelma_arcticus'],'Hadrurus_dominus'],'Gypaetus_schneideri'],'Glareola_leucophyllata'],'Gerrhosaurus_ruficollis'],'Geochelone_filipjevi'],'Gallinago_pallasii'],'Eutamias_multifasciata'],'Eulabeia_tinnunculus'],'Eudrornias_penelope'],'Eudramias_tadorna'],'Eschrichtius_pulchra'],'Eremophila_similis'],'Equus_fluviatilis'],'Epicrates_carinatus'],'Emydura_avosetta'],'Emberiza_japonica'],'Dyscophus_rubicola'],'Dendrelaphis_griseus'],'Cypselus_ceterus'],'Cynops_rutila'],'Cygnus_rubicola'],'Ctenosaura_sphenocercus'],'Coenobita_variabilis'],'Clemmys_caudata'],'Cervus_comicus'],'Castor_prominanus'],'Casarca_holbrooki'],'Capella_aestivus'],'Buthus_nebularia'],'Bronchocela_bicoloratum'],'Branta_ferrumequinum'],'Balaenoptera_piscator'],'Athene_musculus'],'Argynnis_versicolor'],'Arenaria_javanica'],'Anthropoides_aestivus'],'Anolis_medirostris'],'Anodonta_infrafrenata'],'Ambystoma_alcinous'],'Acanthoceros_euptilura']" print(json_loads_wrapper(s)) if __name__ == "__main__": print("Python {:s} on {:s}\n".format(sys.version, sys.platform)) main()

<强>输出：

(py35x64_test) e:\Work\Dev\StackOverflow\q050709371>"e:\Work\Dev\VEnvs\py35x64_test\Scripts\python.exe" code.py Python 3.5.4 (v3.5.4:3f56838, Aug 8 2017, 02:17:05) [MSC v.1900 64 bit (AMD64)] on win32 Trying to parse a 92 level nested list using 'literal_eval': [[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[['0'], '1'], '2'], '3'], '4'], '5'], '6'], '7'], '8'], '9'], '10'], '11'], '12'], '13'], '14'], '15'], '16'], '17'], '18'], '19'], '20'], '21'], '22'], '23'], '24'], '25'], '26'], '27'], '28'], '29'], '30'], '31'], '32'], '33'], '34'], '35'], '36'], '37'], '38'], '39'], '40'], '41'], '42'], '43'], '44'], '45'], '46'], '47'], '48'], '49'], '50'], '51'], '52'], '53'], '54'], '55'], '56'], '57'], '58'], '59'], '60'], '61'], '62'], '63'], '64'], '65'], '66'], '67'], '68'], '69'], '70'], '71'], '72'], '73'], '74'], '75'], '76'], '77'], '78'], '79'], '80'], '81'], '82'], '83'], '84'], '85'], '86'], '87'], '88'], '89'], '90'], '91'] Trying to parse a 93 level nested list using 'literal_eval': s_push: parser stack overflow Traceback (most recent call last): MemoryError Trying to parse a 92 level nested list using 'eval': [[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[['0'], '1'], '2'], '3'], '4'], '5'], '6'], '7'], '8'], '9'], '10'], '11'], '12'], '13'], '14'], '15'], '16'], '17'], '18'], '19'], '20'], '21'], '22'], '23'], '24'], '25'], '26'], '27'], '28'], '29'], '30'], '31'], '32'], '33'], '34'], '35'], '36'], '37'], '38'], '39'], '40'], '41'], '42'], '43'], '44'], '45'], '46'], '47'], '48'], '49'], '50'], '51'], '52'], '53'], '54'], '55'], '56'], '57'], '58'], '59'], '60'], '61'], '62'], '63'], '64'], '65'], '66'], '67'], '68'], '69'], '70'], '71'], '72'], '73'], '74'], '75'], '76'], '77'], '78'], '79'], '80'], '81'], '82'], '83'], '84'], '85'], '86'], '87'], '88'], '89'], '90'], '91'] Trying to parse a 93 level nested list using 'eval': s_push: parser stack overflow Traceback (most recent call last): MemoryError Trying to parse a 92 level nested list using 'json_loads_wrapper': [[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[['0'], '1'], '2'], '3'], '4'], '5'], '6'], '7'], '8'], '9'], '10'], '11'], '12'], '13'], '14'], '15'], '16'], '17'], '18'], '19'], '20'], '21'], '22'], '23'], '24'], '25'], '26'], '27'], '28'], '29'], '30'], '31'], '32'], '33'], '34'], '35'], '36'], '37'], '38'], '39'], '40'], '41'], '42'], '43'], '44'], '45'], '46'], '47'], '48'], '49'], '50'], '51'], '52'], '53'], '54'], '55'], '56'], '57'], '58'], '59'], '60'], '61'], '62'], '63'], '64'], '65'], '66'], '67'], '68'], '69'], '70'], '71'], '72'], '73'], '74'], '75'], '76'], '77'], '78'], '79'], '80'], '81'], '82'], '83'], '84'], '85'], '86'], '87'], '88'], '89'], '90'], '91'] Trying to parse a 93 level nested list using 'json_loads_wrapper': [[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[['0'], '1'], '2'], '3'], '4'], '5'], '6'], '7'], '8'], '9'], '10'], '11'], '12'], '13'], '14'], '15'], '16'], '17'], '18'], '19'], '20'], '21'], '22'], '23'], '24'], '25'], '26'], '27'], '28'], '29'], '30'], '31'], '32'], '33'], '34'], '35'], '36'], '37'], '38'], '39'], '40'], '41'], '42'], '43'], '44'], '45'], '46'], '47'], '48'], '49'], '50'], '51'], '52'], '53'], '54'], '55'], '56'], '57'], '58'], '59'], '60'], '61'], '62'], '63'], '64'], '65'], '66'], '67'], '68'], '69'], '70'], '71'], '72'], '73'], '74'], '75'], '76'], '77'], '78'], '79'], '80'], '81'], '82'], '83'], '84'], '85'], '86'], '87'], '88'], '89'], '90'], '91'], '92'] Original list: [[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[['Xenophrys_bairdii'], 'Vulpanser_spaldingi'], 'Vipera_yeltoniensis'], 'Vipera_minutus'], 'Vanellus_vegans'], 'Vanellus_bedriagai'], 'Ursus_gratiosa'], 'Uroplatus_flavomaculatus'], 'Trionyx_leporosum'], 'Tringa_aspera'], 'Trachemys_sirtalis'], 'Terpsihone_varius'], 'Spermophilus_hassanica'], 'Siniperca_decor'], 'Scolopendra_marcianus'], 'Rufibrenta_montela'], 'Riparia_clinatus'], 'Rhinolophus_tuberculosus'], 'Rhacodactylus_citrsola'], 'Remiz_niloticus'], 'Pterinochilus_physalus'], 'Procellaria_truncatus'], 'Procellaria_lutris'], 'Poephagus_indica'], 'Platemys_albopillosum'], 'Pica_totanus'], 'Pica_mexicana'], 'Phrynomerus_pelagicus'], 'Philothamnus_tuberculosus'], 'Petrocincla_acuta'], 'Pelomedusa_rusticolus'], 'Pagophila_metallica'], 'Pachytriton_sibiricus'], 'Otis_moschata'], 'Otis_franckii'], 'Otis_emarginatus'], 'Opheodrys_clarus'], 'Mylopharyngodon_diffidens'], 'Mergus_carinata'], 'Meles_carbonaria'], 'Mabuya_carnivorus'], 'Lystrophis_siebenrocki'], 'Lyrurus_tinctorius'], 'Lycodon_dendrophila'], 'Lutra_plathyrhychos'], 'Leptopelis_plumipes'], 'Leptopelis_licin'], 'Leiurus_grossmani'], 'Lasiodora_hipposideros'], 'Larus_pulchripes'], 'Kinosternon_guineti'], 'Kassina_canorus'], 'Hysterocrates_chukar'], 'Hydrochelidon_euptilura'], 'Hemitheconyx_pulchripes'], 'Haplopelma_arcticus'], 'Hadrurus_dominus'], 'Gypaetus_schneideri'], 'Glareola_leucophyllata'], 'Gerrhosaurus_ruficollis'], 'Geochelone_filipjevi'], 'Gallinago_pallasii'], 'Eutamias_multifasciata'], 'Eulabeia_tinnunculus'], 'Eudrornias_penelope'], 'Eudramias_tadorna'], 'Eschrichtius_pulchra'], 'Eremophila_similis'], 'Equus_fluviatilis'], 'Epicrates_carinatus'], 'Emydura_avosetta'], 'Emberiza_japonica'], 'Dyscophus_rubicola'], 'Dendrelaphis_griseus'], 'Cypselus_ceterus'], 'Cynops_rutila'], 'Cygnus_rubicola'], 'Ctenosaura_sphenocercus'], 'Coenobita_variabilis'], 'Clemmys_caudata'], 'Cervus_comicus'], 'Castor_prominanus'], 'Casarca_holbrooki'], 'Capella_aestivus'], 'Buthus_nebularia'], 'Bronchocela_bicoloratum'], 'Branta_ferrumequinum'], 'Balaenoptera_piscator'], 'Athene_musculus'], 'Argynnis_versicolor'], 'Arenaria_javanica'], 'Anthropoides_aestivus'], 'Anolis_medirostris'], 'Anodonta_infrafrenata'], 'Ambystoma_alcinous'], 'Acanthoceros_euptilura']

嵌套列表中的ast.literal_eval内存错误

1 个答案: