Почему я не могу преобразовать список str в список с плавающей точкой?

#python #string #list #csv #floating-point

#python #строка #Список #csv #с плавающей запятой

Вопрос:

Я начинаю писать код, но в начале происходит сбой.

Это мой код:

 import csv
reader = csv.reader(open("QstartRefseqhg19.head"), dialect='excel-tab' )

for row in reader:
    C = row[1].split(",")[1:]
    C1 = [float(i) for i in C]

    print C1 
  

и в журнале ошибок написано:

 Traceback (most recent call last):
  File "/home/geparada/workspace/SJtag/src/TagGen.py", line 8, in <module>
    C1 = [float(i) for i in C]
ValueError: empty string for float()
  

Я также пытался

 import csv
reader = csv.reader(open("QstartRefseqhg19.head"), dialect='excel-tab' )

for row in reader:
    C = row[1].split(",")[1:]       
    C1 = map(float, C)        

    print C1
  

Мой входной файл выглядит следующим образом:

 NM_032291   0,227,291,316,388,445,500,676,688,700,725,777,863,956,1031,1532,1660,1787,1847,1959,2115,2248,2451,2516,2681,   tttctctcagcatcttcttggtagcctgcctgtaggtgaagaagcaccagcagcatccatggcctgtcttttggcttaacacttatctcctttggctttgacagcggacggaatagacctcagcagcggcgtggtgaggacttagctgggacctggaatcgtatcctcctgtgttttttcagactccttggaaattaaggaatgcaattctgccaccatgatggaaggattgaaaaaacgtacaaggaaggcctttggaatacggaagaaagaaaaggacactgattctacaggttcaccagatagagatggaattcagcccagcccacacgaaccaccctacaatagcaaagcagagtgtgcgcgtgaaggaggaaaaaaagtttcgaagaaaagcaatggggcaccaaatggattttatgcggaaattgattgggaaagatataactcacctgagctggatgaagaaggctacagcatcagacccgaggaacccggctctaccaaaggaaagcacttttattcttcaagtgaatcggaagaagaagaagaatcacataagaaatttaatatcaagattaaaccattgcaatctaaagacattcttaagaatgctgcaactgtagatgaattgaaggcatcaataggcaacatcgcactttccccatcaccagtgaggaaaagtccgaggcgcagcccgggtgcaattaaaaggaacttatccagtgaagaagtggcaagacccaggcgttccacaccaactccagaacttataagcaaaaagcctccagatgacactacggcccttgctcctctctttggcccaccactagaatcagcttttgatgaacagaagacagaagttcttttagatcagcctgagatatggggttcaggccaaccaattaatccaagcatggagtcgccaaagttaacaaggccttttcccactggaacacctccaccactgcctccaaaaaatgtaccagctaccccaccccgaacaggatcccccttaacaattggaccaggaaatgaccagtcagccacagaggtcaaaattgaaaaactaccatccatcaatgacttggacagcatttttgggccagtattgtcccccaagtctgttgctgttaatgctgaagaaaagtgggtccatttttctgatacatccccggaacatgttactccggagttgactccaagggaaaaagtggtgtccccaccagctacaccagacaacccagctgactccccagctccaggccctctcggccccccaggtcccacaggccccccagggcctcctgggcctcctcgcaatgtactatcgccgctcaatttagaagaagtccagaagaaagtcgctgagcagaccttcattaaagatgattacttagaaacaatctcatctcctaaagattttgggttgggacaaagagcaactccacctcccccaccaccacccacctacaggactgtggtttcgtcccccggacctggctcgggccctggtccggggaccaccagtggtgcatcatcccctgctcgaccagccactcctttggttccttgcagaagtaccactccacctccacctcctccccggcctccatcccggccaaagctacctccaggaaaacctggagttggagatgtgtccagaccttttagccctcccattcattcttccagccctcctccaatagcacccttagcgcgggctgaaagcacttcttcaatatcgtcaaccaattccttgagcgcagccaccactcccacagttgagaatgaacagccttccctcgtttggtttgacagaggaaagttttatttgacttttgaaggttcttccaggggacccagccccctaaccatgggagctcaggacactctccctgttgcagcagcatttacagaaacagtcaatgcctatttcaaaggagcagacccaagcaaatgtatcgttaagattaccggagaaatggtgttgtcatttcctgctggcatcaccagacactttgccaacaacccgtccccagctgctctgacttttcgggtgataaatttcagcaggttagaacacgtcctgccaaacccccaacttctctgctgtgataatacacaaaatgatgccaataccaaggaattctgggtaaacatgccaaatttgatgactcacctaaagaaagtgtctgaacaaaaaccccaggctacatattataacgttgacatgctcaaatatcaggtgtctgcccagggcattcagtccacacctctgaacctggcagtgaattggcgatgtgagccttcaagcactgacctgcgcatagattacaaatataatacagatgcaatgacgactgctgtggccctcaacaatgtgcagttcctggtccccatcgacggaggagtcaccaagctccaggcagtgctcccaccagcagtctggaatgctgaacaacagagaatattgtggaagattcctgatatctctcagaagtcagaaaatggaggggtgggttctttgttggcaagatttcagttatctgaaggcccaagcaaaccttctccattggttgtgcagttcacaagtgaaggaagcaccctttctggctgtgacattgaacttgttggagcagggtatcgattttcactcatcaagaaaaggtttgctgcaggaaaatacttggcagataactaatgaaatcttatgcaaggatttggaggattcatataatggagaactgatgtatgagaaacagattttaattttggtttgatgaaaacaaaccaatatctgcacttgggatatatcaggtggaaagtcaatgactttcatctgtgatttccctcacacactaccatgatgaccagtcctacagtatttacttctaggtgtaatattgttaatggttttaaaatgtaattattgtatttgtaaattgtactctcattccagtaaggcagttagacacttgagttttagcattttaccattcctgaaatggatgtaatttaaactgtggtatgtaaatttaatagtagtattgttgaatggcacaatgcttacagaggtagattgcattttgtcaatatataaaatttaaatataatattgatagctgtcataaagggggtgccacatattaaagaaacttaagtggaaccagaagaaaaagaaacaaacttacttttcttcaatgcttagtatgttttactctagtgctaaataaaaactctatcttcaaatgtttagtgggttaaattgagaaactatttcagaaaaaaattctaaggttacagcatattcaaagaaaagcattagttaccactttttaaaaagcttttttttcaaactgcaaatttcataaaaatgcaaactgtgtaaacagggcctcttatttttataacttgtgtaaaaagggaaagcaattcatatttaaagtttaagtatattaaattataatcaagagtaaagaagatgttgaagtcttaactacttgcccctctctacagtttcgcaaatgtggggattgctgaataatcagtcagactaaaaccaaaattgtgattttaagatttcaagactttccgtagttgaactggttaagaatttttgcttagttactctgaatagatgatcttactcatccagtatgggggaatgatacctcacgtcttcctctttacccacaggaatcaaaacgctgagactgagaattttagggaaaaaaaagtccactgtttagatccagaaggagagttttaatcattgtttatatcatttgagaatgaaaaaataagcttcataaatgaaattctattcacattactgtgtaataaatttccttttggatgattaggattcattgtataaaactgtaaatctttgccattcttggagaagcaaaaggagagttatcaaaaatgtatgtcgtttcatcgttgcaaggtataataaaaactgtaattattcaatctggccctgccatatgaacatttagaaagacaaacttcttcgggagtctcagttgtaaaaccttccctcattaatatctgaaaatgttagtcttcctttaagtcatagaacttatttaaacataaaccaatttctattacaggttatgctattaaatagctgtaattattaagttattatttttataattagttgttaaatttcattttacacccactcaaatttaacaaagaatctttagcccctttaaattttagaattaaattaaatttttaaagttttacttctaaaatgagattgtgactggcaattgtttatagtgaaactttttaaattaatctttgtactcctctatcagtgcttgctaccaagagaatgtccaaaatgatttgttttaccatgggaaaattcttactattcaacaaactctcagttggccccctacagcagtctggtgttgaagtttctttgaacgaactaaatatactcattttatgtaaaggtatccaatttgattttgaaaccaaaatagaaaatgcaaaattctaaattccatgaaacatggaatttatgacaccaaaatcaatggagagtaagcagcagcaaactgagaattatccagcatatgaatataacaatgtgtttttaagtaatcaattcatttaaaaaattgaatattaatacaaagcatattaaaaacatgtaaatatta
NM_001080397    0,397,490,715,1443,1597,1774,1980,  atgatccccgcagccagcagcaccccgccgggagatgccctcttccccagcgtggccccacaggacttctggaggtcccaggtcacgggctactcggggtccgtgacacgacacctcagtcaccgggccaacaacttcaaacgacaccccaagaggaggaagtgcattcgtccctccccacccccgccccccaacaccccgtgcccgcttgagctggtggacttcggggacctgcacccccagaggtccttccgggagctgcttttcaacggctgcattctctttggcatcgagttcagctacgccatggagacggcgtacgtgaccccggtgctcctgcagatgggcctgcccgaccagctctacagcctggtgtggttcatcagccccatcctcggattcctactgcagcctctgttgggtgcttggagtgaccggtgtacctcaaggtttggaaggagacgccctttcattcttgtcctggctataggggcactgctgggcctctcgctcttgctgaatggccgggacattggcatcgccctggctgacgtgaccgggaaccacaagtggggcctgctgctgaccgtgtgcggtgtggtgctgatggactttagcgccgactcggcggacaaccccagccacgcctacatgatggacgtgtgcagccccgcagaccaggaccgaggcctgaacatccacgccctcctggcaggtctcggaggaggctttggatacgtggtcggcggaatccactgggataaaacgggcttcgggagggccctggggggacagctccgagtcatttacctcttcactgcggtcaccctgagcgtcaccaccgtcctgaccctggtcagcatccctgagaggccgctgcggccgccgagtgagaagcgggcagccatgaagagccccagcctcccgctgcccccgtccccacccgtcctgccagaggaaggccctggcgacagcctcccgtcgcacacggccaccaacttctccagccccatctcgccgcccagccccctcacgcccaagtacggcagcttcatcagcagggacagctccctgacgggcatcagcgagttcgcctcatcctttggcacggccaacatagacagcgtcctcattgactgcttcacgggcggccacgacagctacctggccatccctggcagcgtccccaggccgcccatcagcgtcagcttcccccgggcccccgacggcttctaccgccaggaccgtggacttctggagggcagagagggtgccctgacctccggctgtgacggggacattctgagggtgggctccttggacacctctaagccgaggtcatcagggattctgaagagacctcagaccttggccatcccggacgcagccggaggagggggtcccgaaaccagcaggagaaggaatgtgaccttcagtcagcaggtggccaatatcctgctcaacggcgtgaagtatgagagcgagctgacgggctccagcgagcgcgcggagcagcctctgtccgtggggcgcctctgctccaccatctgcaacatgcccaaggcgctacgcaccctctgcgtcaaccacttcctggggtggctctcattcgaggggatgttgctcttctacacagacttcatgggcgaggtggtgtttcagggggaccccaaggccccgcacacatcagaggcgtatcagaagtacaacagcggcgtgaccatgggctgctggggcatgtgtatctacgccttcagtgctgccttctactcagctatcctggagaagctggaggagttcctcagcgtccgcaccctctacttcatcgcctatctcgccttcggcctggggaccgggcttgccaccctctccaggaacctctacgtggtcctgtcgctctgcataacctacgggattttattttccaccctgtgcaccttgccttactcgctgctctgcgattactatcagagtaagaagtttgcagggtccagtgcggacggcacccggcggggcatgggcgtggacatctctctgctgagctgccagtacttcctggctcagattctggtctccctggtcctggggcccctgacctcggccgtgggcagtgccaacggggtgatgtacttctccagcctcgtgtccttcctgggctgcctgtactcctccctgtttgtcatttatgaaattcctcccagcgacgctgcagacgaggagcaccggcccctcctgctgaacgtctgacatcgcggagcctcgactccggacacgcgcctgcacctgggggtctggagcaggccgaccagtgaggaccaaagggccttgttggacagggggactggctgcctactggaatgtaaatatgtgataaaataataaatgacagcggcaaagccta
NM_001145277    0,182,283,388,470,579,757,  gaaacctggtcagagagtcgcaccgcttccgtccgtcggacagaggaacggtggaagtcgccggaagttcggtgggctccaggcgtcgcgatggaggagagcgggtacgagtcggtgctctgtgtcaagcctgacgtccacgtctaccgcatccctccgcgggctaccaaccgtggctacagggctgcggagtggcagctggaccagccatcatggagtggccggctgaggatcactgcaaagggacagatggcctacatcaagctggaggacaggacgtcaggggagctctttgctcaggccccggtggatcagtttcctggcacagctgtggagagtgtgacggattccagcaggtacttcgtgatccgcatcgaagatggaaatgggcgacgggcgtttattggaattggcttcggggaccgaggtgatgcctttgacttcaatgttgcattgcaggaccatttcaagtgggtgaaacagcagtgtgaatttgcaaaacaagcccagaacccagaccaaggccctaaactggacctgggcttcaaggagggccagaccatcaagctcaacatcgcaaacatgaagaagaaggaaggagcagctgggaatccccgagtccggcctgccagcacaggagggctgagcctgcttccccctcccccaggggggaaaacctccaccctgatccctccccctggggagcagttggctgtggggggatccctcgtccagccagcagttgctcccagttcagatcaacttccagccagacccagccaggcacaggctgggtccagttctgacctgagcacggtttttcctcatgtgacttctgggaaggcgctccctcatctgggccaaaggaaggaggacgaagccctcctcagctggcctgtgtttggggcatgaatctctcctctcctccttgtctggctctgttgacaaaccgggcatgtttggcagtaaattggcaccgtgtcacactgtttcctgggattcaagtatgcaaccagaacacaggagaagaaaagctccaggatccctgtccccatctgtcctcttgatgtgagagagactctgagacttcttccatcgcaatgacctgtattaaacacaagccccccaagcaaaagaagaggttgagtttgctgccaggattcagatcagcccttcccagggtctgcaggtgtcacatgatcacagttcagcgggaggctttccgtacccacactggctgtagccacttcagtccatctgccctccagaggaggggtttcttcctgatttttagcaggtttagaggctgcagcttgagctacaatcaggagggaaattggaaggattagcagcttttaaaaatgtttaaatattttgctttgctaatgtgctgatccgcactaactcatctttgcaaaaggaactgctccctcggcgtgccccagctggggcctctgaagggattcctcactgtgggcagctgccctgagcttcaggcagcagtgtttatctctggccagttgtctggtttccatgtattctaggccaggtaggcaacacagagccaaggcgggtgctggaagccagacggaacagtgttggggcaggaaggtggatgctgttgtcatggagctgtgggagttggcactctgtctgctggtggccctctcggctcacatgttcacagtgcagctcctggcagacttgggttttctctttggtggtttctaaagtgccttatctgcaaacaacttcttttctccttcaggaactgtgaatggctagaagaaggagctcagtaaactagaagtccagggttgcttggtttactggtttataagaaatctgaaagcacctctgacattccttttattaactcacctctcagttgaaagatttcttctttgaaaggtcaagaccgtgaactgaaaaaagtgttggcctttttgcgggaccagatttttaagataaaataaatatttttacttctgtcattgtatgtgaaaaaaaaaaaaa
  

Я стек, спасибо за ваше время!!

Комментарии:

1. совет по отладке: перед операцией failing выполните print "C:", C

Ответ №1:

Ваша строка ввода заканчивается запятой, например:

 0,182,283,388,470,579,757,
  

Естественно, это будет разделено на:

 ['0', '182', '283', '388', '470', '579', '757', '']
  

Последним элементом всегда будет пустая строка, '' . Вам нужно было бы учесть это. Один из способов — просто игнорировать это:

 C1 = [float(i) for i in C if i]
  

Или путем вырезания последнего элемента перед приведением:

 C = row[1].split(",")[1:-1]   # the slice will exclude first and last elements
  

Комментарии:

1. Или вы можете сначала использовать strip() метод: C = row[1].strip(',').split(',')[1:]

2. @Blair: Я должен был это сказать. Спасибо, что указали на это. Кажется, вчера в какой-то момент мой разум сломался. Надеюсь, теперь это исправлено.

Ответ №2:

вы могли бы использовать try / except при преобразовании в float и перехватывать ValueErrors.

 C = row[1].split(",")[1:] 
    for item in C:
    try:
        convert=float(item)
    except ValueError:
        print "not a number"