Why can't I convert the str list to a list of floats?

Question

I am starting to write code, but it does not work in the beginning.

This is my code:

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 

, and the error log says:

 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() 

I also tried

 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 

My input file is as follows:

 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 

I'm stop, thanks for your time!

Answer 1

Your input line ends with a comma, for example:

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

So naturally, this will be divided into:

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

The last item will always be an empty string, '' . You will need to explain this. One way is to simply ignore this:

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

Or by cutting the last item before casting:

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

Answer 2

you can use try / except when converting to float and catch ValueErrors.

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