除了计数之外，还有其他方法可以计算字符串中的重复次数吗？

Question

我正在做 CS50 DNA 题，python 计数函数不断返回值，我不确定为什么。我尝试使用查找，但我的实现是错误的

import csv, sys
#check if all arguments are provided
if len(sys.argv) != 3:
    print("Usage: python dna.py data.csv sequence.txt")
    exit()

#sets database to first argument
databaseFile = sys.argv[1]

#sequence is second file
sequenceFile = sys.argv[2]

#make list for data
data = []
database = []

#open csv file
with open(databaseFile, 'r') as csvfile:

    #make reader
    csvreader = csv.reader(csvfile)

    #read in the headers
    fields = next(csvreader)
    fields.remove("name")

    #read in the rows of data in database
    for row in csvreader:
        #add data, with names and database with just numbers
        data.append(row)
        database.append([int(i) for i in row[1:]])

#open sequence
sequence = open(sequenceFile, 'r').readline()

results = []
#for add repetitions to results
for field in fields:
    results.append(sequence.count(field))

print(results)
found = False
for i in database:
    if (results == i):
        print(data[i])
        found = True
if not found:
    print("No match")

还有什么方法可以按顺序计算'field'的重复次数例如当我加载时：

python dna.py databases/large.csv sequences/19.txt 我得到的结果是： [47, 40, 34, 11, 24, 31, 60, 26] No match

而不是弗雷德即：[37, 40, 10, 6, 5, 10, 28, 8]

可以在以下位置找到问题：https://cs50.harvard.edu/x/2020/psets/6/dna/

Answer 1

使用正则表达式查找连续的匹配项。

import re

s = 'AGTCAGTCAGTCTTTTAGCTAGTC'
STR = 'AGTC'

strands = re.findall(f'(?:{STR})+', s)
print(strands) # prints `['AGTCAGTCAGTC', 'AGTC']`

my_max = max(map(len, strands))//len(STR)
print(my_max)

打印 3 这是正确的，因为它连续出现 3 次（并且在序列末尾再次出现）。

我希望这段代码可以帮助您解决这部分问题。

除了计数之外，还有其他方法可以计算字符串中的重复次数吗？

Is there a different way to count repetitions in a string except count?

python

cs50