值错误：项目不在列表中，但显然是

Question

我有一个列表，abbreviations，里面装满了字符串对象。我正在尝试调用列表中字符串的.index。当我用字符串调用.index 方法时，我得到一个ValueError：'LING'不在列表中，而它显然在列表中。

我的代码：

for item in abbreviations:
    print item

print abbreviations.index("LING")

为什么“LING”不存在，而它清除存在？我添加了以下代码行，它在“缩写”中搜索字符串的索引。我很困惑——“LING”显然在我的缩写列表中。

编辑（附加代码）：

import csv 

myfile = open("/Users/it/Desktop/Classbook/classAbrevs.csv", "rU")

lines = [tuple(row) for row in csv.reader(myfile)]

longSubjectNames = [] 
abbreviations = [] 

masterAbrevs = []
for item in lines:
    longSubjectNames.append(item[0])
    abbreviations.append(item[1])

with open ("/Users/it/Desktop/Classbook/masterClassList.txt", "r") as myfile:
    masterSchedule = tuple(open("/Users/it/Desktop/Classbook/masterClassList.txt", 'r'))

for masterline in masterSchedule:
    masterline.strip()
    masterSplitLine = masterline.split("|")

    subjectAbrev = ""
    if masterSplitLine[0] != "STATUS":
        subjectAbrev = ''.join([i for i in masterSplitLine[2] if not i.isdigit()])
        masterAbrevs.append(subjectAbrev)

finalAbrevs = []
for subject in masterAbrevs:
    if (subject[-1] == 'W') and (subject[-2:] != 'UW'): 
        subject = subject[:-1]
    finalAbrevs.append(subject)

x = 0

for item in abbreviations:
    print item

print abbreviations.index("LING")

for item in finalAbrevs:
    if masterSplitLine[0] != "STATUS":
        concat = abbreviations.index(str(finalAbrevs[x]).strip())
        print "The abbreviation for " + str(item) + " is: " + longSubjectNames[concat]
    x = x + 1

输出：

masterAbrevs = []
for item in lines:
    longSubjectNames.append(item[0])
    abbreviations.append(item[1])

print '-'.join(abbreviations)

是：

ACA-ACCY-AFST-AMST-ANAT-ANTH-APSC-ARAB-AH-FA-ASTR-BIOC-BISC-BME-BMSC-BIOS-BADM-CHEM-CHIN-CE-CLAS-CCAS-COMM-CSCI-CFA-CNSL-CPED-DNSC-EALL-ECON-EDUC-ECE-EHS-ENGL-EAP-EMSE-ENRP-EPID-EXSC-FILM-FINA-FORS-FREN-GEOG-GEOL-GER-GREK-HCS-HSCI-HLWL-HSML-HEBR-HIST-HOMP-HONR-HDEV-HOL-HSSJ-ISTM-IDIS-IAD-INTD-IAFF-IBUS-ITAL-JAPN-JSTD-KOR-LATN-LAW-LSPA-LING	-MGT-MKTG-MBAD-MATH-MAE-MED-MICR-MMED-MSTD-MUS-NSC-ORSC-PSTD-PERS-PHAR-PHIL-PT-PA-PHYS-PMGT-PPSY-PSC-PORT-PSMB-PSYD-PSYC-PUBH-PPPA-REL-SEAS-SMPA-SLAV-SOC-SPAN-SPED-SPHR-STAT-SMPP-SUST-TRDA-TSTD-TURK-UW-WLP-WSTU
Traceback (most recent call last):
  File "/Users/it/Desktop/Classbook/sortClasses.py", line 25, in <module>
    with open ("/Users/it/Desktop/Classbook/masterClassList.txt", "r") as anything:
IOError: [Errno 2] No such file or directory: '/Users/it/Desktop/Classbook/masterClassList.txt'

Answer 1

myfile = open("/Users/it/Desktop/Classbook/classAbrevs.csv", "rU")

lines = [tuple(row) for row in csv.reader(myfile)]

longSubjectNames = [] 
abbreviations = [] 

masterAbrevs = []
for item in lines:
    longSubjectNames.append(item[0])
    abbreviations.append(item[1])

with open ("/Users/it/Desktop/Classbook/masterClassList.txt", "r") as myfile:

问题就在这里；

with open ("/Users/it/Desktop/Classbook/masterClassList.txt", "r") as myfile:

你在这里定义了myfile之前，

myfile = open("/Users/it/Desktop/Classbook/classAbrevs.csv", "rU")

所以实际上abbreviations = [] 并没有从classAbrevs.csv 获取数据。因为它是从masterClassList.txt 获取数据，正如你用这一行定义的myfile；

with open ("/Users/it/Desktop/Classbook/masterClassList.txt", "r") as myfile

这就是为什么您的字符串不在该列表中的原因。还有这一行；

for item in lines:
    longSubjectNames.append(item[0])
    abbreviations.append(item[1])

你确定item[1] 有你想要的所有字符串吗？

我尝试了这些代码，我只是从你的代码中复制粘贴，结果如下；

Answer 2

问题是，从你运行的结果来看：

“LING\t” 显示在您的列表中，而不是 “LING”

通过运行我得到所需的索引：

abbreviations.index("LING\t")

71

为了纠正这个问题，有很多方法可以去除 \t，我将展示其中一种：

abbreviations.append(item[1].strip())

通过更正此行，您的 item[1] 将在添加到您的 abbreviations 列表之前去除 \t。