带有字符串和函数的python return语句

Question

def intron_comparison(retained_introns_file, non_retained_introns_file): 
    with open(retained_introns_file, 'r') as r, open(non_retained_introns_file, 'r') as nr: 
     r_gc = avg_gc(r) 
     nr_gc = avg_gc(nr) 
     r_avglen = intlength(r) 
     nr_avglen = intlength(nr) 
     r_percdiv = intdiv(r) 
     nr_percdiv = intdiv(nr) 
    return ('The GC content for non retained introns is ' + nr_gc + '\n' + 
     'The GC content for retained introns is ' + r_gc + '\n' + 
     'The average length of non retained introns is ' + nr_avglen + '\n' + 
     'The average length of retained introns is ' + r_avglen + '\n' + 
     'The percent of non retained introns divisible by 3 is ' + nr_percdiv + '\n' + 
     'The percent of retained introns divisible by 3 is ' + r_percdiv + '.') 

上面是我写的一个函数，它将3个其他函数合并在一起，并在它们之间比较2个文件。我想在return语句前值来表示一个描述符，你可以看到，但我收到以下错误：

TypeError: Can't convert 'NoneType' object to str implicitly 

关于最后一行。我错过了什么？

编辑：代码奇妙地工作，我只是有这个返回语句的问题 - 我认为这是我失踪的一些小事情？预先感谢您的帮助！

Answer 1

对于像你所做的一些事情的大字符串。

首先使用“”“”“”而不是试图按照自己的方式来构建它。

第二次使用％样式或格式将值内插到字符串中。较新的python建议是使用格式。

return """The GC content for non retained introns is {nr_gc} 
The GC content for retained introns is {r_gc} 
The average length of non retained introns is {nr_avglen} 
The average length of retained introns is {r_avglen} 
The percent of non retained introns divisible by 3 is {nr_percdiv} 
The percent of retained introns divisible by 3 is {r_percdiv}. 
""".format(r_gc = avg_gc(r), 
      nr_gc = avg_gc(nr), 
      r_avglen = intlength(r), 
      nr_avglen = intlength(nr), 
      r_percdiv = intdiv(r) 
      nr_percdiv = intdiv(nr))