我写了一个python程序以计算字符串出现频率，这个程序总是少算最后一行的最后一个字符，这是怎么回事？

问题遇到的现象和发生背景

>1
qq
>2
wwwwwwwwwwwwww
>3
qqqqqweqeq
>4
rrrrrrrrrrrrrrrrrr
>5
tttttttttttttttttttt
>6
ddssaa

问题相关代码，请勿粘贴截图

import pandas as pd
import os

leng=1
f = open("111.fna","r")
lines = f.readline()
chr = 0
l = 1

thefile = open("111.fna","r")

while True:
    buffer = thefile.read()
    if not buffer:
        break
    l += buffer.count('\n')
thefile.close()
lp = l + 1
h = 1   # 计算行数
while True:
    if ">" in lines:  # 如果有>号，
        chr = chr + 1
        lines = f.readline()  #则读取下一行
        h = h + 1

    exec("dic%s=dict()"%chr)
    for i in range(len(lines)-leng):
        sub = lines[i:i+leng]
        exec("x = dic%s.keys()"%chr)
        if sub in x:
            exec("dic%s[sub] += 1"%chr)
        else:
            exec("dic%s[sub] = 1"%chr)
    exec("df%s=pd.DataFrame([dic%s])"%(chr,chr))
    outputpath = "C"+str(chr)+"-"+str(leng)+'NCount.csv'
    exec("df%s.to_csv(outputpath,sep=',',index=False,header=True)"%chr)
    lines = f.readline()
    h = h + 1
    if h >= l + 1:
        break


f.close()

运行结果及报错内容

此时的
dic1={'q': 2}
dic2={'w': 14}
……（前5个字典均正常）……
dic6={'d': 2, 's': 2, 'a': 1}
少一个a。

我的解答思路和尝试过的方法

我用过直接readline，但是总是不能读取最后一行，才先计算行数再计数。

我想要达到的结果

dic6=dic6={'d': 2, 's': 2, 'a': 2}
注：用字典计算字符串频率的方法来自https://ask.csdn.net/questions/7405804?spm=1001.2014.3001.5501

因为最后一行没有回车，你还是减了一个leng

import pandas as pd 
from collections import Counter

with open(filename) as f:
    i = 0
    x = f.readline().replace("\n", '')
    while x:
        if ">" not in x:
            s = f"dic{i}=dict(Counter('" + x + "'))"
            exec(s)
            exec(f"print(dic{i})")
            exec(f"df=pd.DataFrame([dic{i}])")
            outputpath = dirname + f"\\C{i}"+'NCount.csv'
            ss =  "df.to_csv(r'" + outputpath + "',sep=',',encoding='utf-8',index=False,header=True)"
            exec(ss)
            i += 1       

        x = f.readline().replace("\n", '')