python循环字典值引用更新所有值

Question

我在更新 python 字典中的值时遇到问题。我正在尝试更新单个拳头级键的嵌套值(作为 int 或列表)，但我更新了所有第一级键的值。

我从创建字典开始:

kmerdict = {}
innerdict = {'endcover':0, 'coverdict':{}, 'coverholder':[], 'uncovered':0, 'lowstart':0,'totaluncover':0, 'totalbases':0}
for kmer in kmerlist: # build kmerdict
    kmerdict [kmer] = {}
    for chrom in fas:  #open file and read line
        chromnum = chrom[3:-3]
        kmerdict [kmer][chromnum] = innerdict

然后我从列表(fas，未显示)中遍历染色体(作为纯文本文件)，并将 7mer 字符串 (k=7) 作为键。如果该键在我要查找的键列表 (kmerlist) 中并尝试使用它来引用嵌套在字典中的单个值:

for chrom in fas:  #open file and read line
    chromnum = chrom[3:-3]
    p = 0  #chromosome position counter
    thisfile = "/var/store/fa/" + chrom
    thischrom = open(thisfile)
    thischrom.readline()
    thisline = thischrom.readline()
    thisline = string.strip(thisline.lower())
    l=0  #line counter
    workline = thisline
    while(thisline):
        if len(workline) > k-1:
            thiskmer = ''
            thiskmer = workline[0:k] #read five bases
            if thiskmer in kmerlist:
                thisuncovered = kmerdict[thiskmer][chromnum]['uncovered']
                thisendcover =  kmerdict[thiskmer][chromnum]['endcover']
                thiscoverholder = kmerdict[thiskmer][chromnum]['coverholder']
                if p >= thisendcover:
                    thisuncovered += (p - thisendcover)
                    thisendcover = ((p+k) + ext)
                    thiscoverholder.append(p)
                elif p < thisendcover:
                    thisendcover = ((p+k) + ext)
                    thiscoverholder.append(p)
            print kmerdict[thiskmer]
            p += 1
            workline = workline[1:]
        else:
            thisline = thischrom.readline()
            thisline = string.strip(thisline.lower())
            workline = workline+thisline
            l+=1
print kmerdict

但是当我打印字典时，所有“thiskmer”级别都会更新为相同的值。我不太会用字典，我也看不出我的方法有什么错误，但它们很深奥!谁能赐教一下？

希望我已经说得足够清楚了。我已经修改这段代码太久了:(

Answer 1

忏悔 -- 我没有花时间弄清楚你的所有代码 -- 只有第一部分。您遇到的第一个问题是在设置中:

kmerdict = {}
innerdict = {'endcover':0, 'coverdict':{}, 'coverholder':[], 'uncovered':0, 
             'lowstart':0,'totaluncover':0, 'totalbases':0}
for kmer in kmerlist: # build kmerdict
    kmerdict [kmer] = {}
    for chrom in fas:  #open file and read line
        chromnum = chrom[3:-3]
        kmerdict [kmer][chromnum] = innerdict

您创建了一次innerdict，然后又继续使用同一个字典。换句话说，每个 kmerdict[kmer][chromnum] 都指向相同的对象。也许将最后一行更改为:

kmerdict [kmer][chromnum] = copy.deepcopy(innerdict)

会有所帮助(在文件顶部适当导入 copy)吗？或者，您可以将 innerdict 的创建移动到注释中指出的内部循环中:

def get_inner_dict():
    return {'endcover':0, 'coverdict':{}, 'coverholder':[], 'uncovered':0, 
            'lowstart':0,'totaluncover':0, 'totalbases':0}

kmerdict = {}
for kmer in kmerlist: # build kmerdict
    kmerdict [kmer] = {}
    for chrom in fas:  #open file and read line
        chromnum = chrom[3:-3]
        kmerdict [kmer][chromnum] = get_inner_dict()

-- 我决定使用一个函数来使其更易于阅读:)。