的Python：字符串格式化其中线长度可以变化

Question

所以，我有下面的脚本：

def single_to_tripple(res): 
    aa = {'R':'ARG','H':'HIS','K':'LYS','D':'ASP','E':'GLU','S':'SER','T':'THR','N':'ASN','Q':'GLN','C':'CYS','U':'SEC','G':'GLY','P':'PRO','A':'ALA','I':'ILE','L':'LEU','M':'MET','F':'PHE','W':'TRP','Y':'TYR','V':'VAL'} 
    return(aa[res]) 
seq = 'ASALKDYYAIMGVKPTDDLKTIKTAYRRLARKYHPDVSKEPDAEARFKEVAEAWEVLSDEQRRAEYDQMWQHRNDPQFNRQFHHGDGQSFNAEDFDDIFSSIFGQHARQSRQRPATRGHDIEIEVAVFLEETLTEHKRTISYNLPVYNAFGMIEQEIPKTLNVKIPAGVGNGQRIRLKGQGTPGENGGPNGDLWLVIHIAPHPLFDIVGQDLEIVVPVSPWEAALGAKVTVPTLKESILLTIPPGSQAGQRLRVKGKGLVSKKQTGDLYAVLKIVMPPKPDENTAALWQQLADAQSSFDPRKDWGKA' 
length = len(seq) 

for i,v in enumerate(xrange(0,len(seq),13)): 
    line = seq[v:v+13] 
    out_line = ('{:<3} '*13).format(single_to_tripple(line[0]),single_to_tripple(line[1]),single_to_tripple(line[2]),single_to_tripple(line[3]),single_to_tripple(line[4]),single_to_tripple(line[5]),single_to_tripple(line[6]),single_to_tripple(line[7]),single_to_tripple(line[8]),single_to_tripple(line[9]),single_to_tripple(line[10]),single_to_tripple(line[11]),single_to_tripple(line[12])) 
    print out_line 

我使用的脚本来拼接seq串每隔13个元素，然后将每个元件从所述拼接字符串中其单字母代码在single_to_tripple的三位字母代码中。我的数据输出需要包含13个由空格分隔的列。如果拼接不包含13个元素，则会在最后一个拼接处发生问题。我怎样才能抓住这一点，并像往常一样格式化字符串？

我在我的for循环中使用了enumerate，因为我需要在以后添加行号。

我当前的代码输出：

ALA SER ALA LEU LYS ASP TYR TYR ALA ILE MET GLY VAL 
LYS PRO THR ASP ASP LEU LYS THR ILE LYS THR ALA TYR 
ARG ARG LEU ALA ARG LYS TYR HIS PRO ASP VAL SER LYS 
GLU PRO ASP ALA GLU ALA ARG PHE LYS GLU VAL ALA GLU 
ALA TRP GLU VAL LEU SER ASP GLU GLN ARG ARG ALA GLU 
TYR ASP GLN MET TRP GLN HIS ARG ASN ASP PRO GLN PHE 
ASN ARG GLN PHE HIS HIS GLY ASP GLY GLN SER PHE ASN 
ALA GLU ASP PHE ASP ASP ILE PHE SER SER ILE PHE GLY 
GLN HIS ALA ARG GLN SER ARG GLN ARG PRO ALA THR ARG 
GLY HIS ASP ILE GLU ILE GLU VAL ALA VAL PHE LEU GLU 
GLU THR LEU THR GLU HIS LYS ARG THR ILE SER TYR ASN 
LEU PRO VAL TYR ASN ALA PHE GLY MET ILE GLU GLN GLU 
ILE PRO LYS THR LEU ASN VAL LYS ILE PRO ALA GLY VAL 
GLY ASN GLY GLN ARG ILE ARG LEU LYS GLY GLN GLY THR 
PRO GLY GLU ASN GLY GLY PRO ASN GLY ASP LEU TRP LEU 
VAL ILE HIS ILE ALA PRO HIS PRO LEU PHE ASP ILE VAL 
GLY GLN ASP LEU GLU ILE VAL VAL PRO VAL SER PRO TRP 
GLU ALA ALA LEU GLY ALA LYS VAL THR VAL PRO THR LEU 
LYS GLU SER ILE LEU LEU THR ILE PRO PRO GLY SER GLN 
ALA GLY GLN ARG LEU ARG VAL LYS GLY LYS GLY LEU VAL 
SER LYS LYS GLN THR GLY ASP LEU TYR ALA VAL LEU LYS 
ILE VAL MET PRO PRO LYS PRO ASP GLU ASN THR ALA ALA 
LEU TRP GLN GLN LEU ALA ASP ALA GLN SER SER PHE ASP 
Traceback (most recent call last): 
    File "make_seq_res.py", line 10, in <module> 
    out_line = ('{:<3} '*13).format(single_to_tripple(line[0]),single_to_tripple(line[1]),single_to_tripple(line[2]),single_to_tripple(line[3]),single_to_tripple(line[4]),single_to_tripple(line[5]),single_to_tripple(line[6]),single_to_tripple(line[7]),single_to_tripple(line[8]),single_to_tripple(line[9]),single_to_tripple(line[10]),single_to_tripple(line[11]),single_to_tripple(line[12])) 
IndexError: string index out of range 

Answer 1

，你必须键入了许多变数手动应该给你，你正在做的比必要的做法，以产生输出暗示的事实。

没有太大变化的原密码，能做到这一点是这样的：

for i,v in enumerate(xrange(0,len(seq),13)): 
    line = seq[v:v+13] 
    out_line = ' '.join('{:<3}'.format(single_to_tripple(part)) for part in line) 
    print out_line 

正如马亭指出，三胞胎总是三个字符，所以实际上你可以跳过格式：

out_line = ' '.join(single_to_tripple(part) for part in line) 

Answer 2

您可以保存您的线路长度，比使用它：

def single_to_tripple(res): 
    aa = {'R':'ARG','H':'HIS','K':'LYS','D':'ASP','E':'GLU','S':'SER','T':'THR','N':'ASN','Q':'GLN','C':'CYS','U':'SEC','G':'GLY','P':'PRO','A':'ALA','I':'ILE','L':'LEU','M':'MET','F':'PHE','W':'TRP','Y':'TYR','V':'VAL'} 
    return(aa[res]) 

seq = 'ASALKDYYAIMGVKPTDDLKTIKTAYRRLARKYHPDVSKEPDAEARFKEVAEAWEVLSDEQRRAEYDQMWQHRNDPQFNRQFHHGDGQSFNAEDFDDIFSSIFGQHARQSRQRPATRGHDIEIEVAVFLEETLTEHKRTISYNLPVYNAFGMIEQEIPKTLNVKIPAGVGNGQRIRLKGQGTPGENGGPNGDLWLVIHIAPHPLFDIVGQDLEIVVPVSPWEAALGAKVTVPTLKESILLTIPPGSQAGQRLRVKGKGLVSKKQTGDLYAVLKIVMPPKPDENTAALWQQLADAQSSFDPRKDWGKA' 
length = len(seq) 

for i,v in enumerate(xrange(0,len(seq),13)): 
    line = seq[v:v+13] 
    length = len(line) 
    out_line = ('{:<3} '*length).format(*[single_to_tripple(a) for a in line]) 
    print out_line 

Answer 3

你仅仅局限于N不需要格式化：

for i,v in enumerate(xrange(0,len(seq),13)): 
    line = seq[v:v+13] 
    print ' '.join([single_to_tripple(part) for part in line]) 

没有必要在这里过分复杂。 :-)

注意，使用str.join()时，使用列表理解了生成器表达式（所以包括[...]）为.join()将转换为一个列表反正上榜理解得更快。

结果（最后3行）：

ILE VAL MET PRO PRO LYS PRO ASP GLU ASN THR ALA ALA 
LEU TRP GLN GLN LEU ALA ASP ALA GLN SER SER PHE ASP 
PRO ARG LYS ASP TRP GLY LYS ALA 

你也可以使用一个基于itertools石斑鱼，以简化你的循环：

from itertools import izip_longest 

def grouper(n, iterable, padvalue=None): 
    "grouper(3, 'abcdefg', 'x') --> ('a','b','c'), ('d','e','f'), ('g','x','x')" 
    return izip_longest(*[iter(iterable)]*n, fillvalue=padvalue) 

aa = {'R':'ARG','H':'HIS','K':'LYS','D':'ASP','E':'GLU','S':'SER','T':'THR','N':'ASN','Q':'GLN','C':'CYS','U':'SEC','G':'GLY','P':'PRO','A':'ALA','I':'ILE','L':'LEU','M':'MET','F':'PHE','W':'TRP','Y':'TYR','V':'VAL', None: ''} 
def single_to_tripple(res): 
    return(aa[res]) 

for line in grouper(13, seq): 
    print ' '.join([single_to_tripple(part) for part in line]) 

，我通过移动映射增进了你的single_to_tripple()功能出的功能（不需要定义它每个和每时间你称它），一个d增加一个None键（石斑填补None值的最后一组）。