Python 如何拆分字符串，使其包含的字符数少于n个（带扭曲）

我有一个长字符串要保存到文件中。单词之间用空格隔开。给出了长字符串中的字数可以被3整除

基本上，我在寻找一种将字符串分割成块的方法。每个区块少于n个字符，区块中的字数也可被3整除

e、 g

假设最大线长度为n=30：

>>>split_string(longstring, 30)
['This is a very long string', 'and the sum of words is', 'divisible by three']

总之，这些规则是：

不超过n个字符的行

一个转折点是每一行必须包含3个单词的倍数

到目前为止，我尝试使用textwrap，但我不知道如何实现2

import textwrap    
textwrap.fill(long_line, width=69)

---

如果确定字符串中的总字数始终可以被3整除，则可以执行以下操作：

import sys
#long string; 84 words; divisible by 3
longString = "The charges are still sealed under orders from a federal judge. Plans were prepared Friday for anyone charged to be into custody as soon as Monday, the sources said. It is unclear what the charges are. A spokesman for the special counsel's office declined to comment. The White House also had no comment, a senior administration official said Saturday morning. A spokesman for the special counsel's office declined to comment. The White House also had no comment, a senior administration official said Saturday morning."
#convert string to list
listOfWords = longString.split()
#list to contain lines
lines = []
#make sure number of words is divisible by 3
if  len(listOfWords) % 3 != 0:
    #exit
    print "words number is not divisible by 3"
    sys.exit()
#keep going until list is empty
while listOfWords:

    i = 0
    line = ""
    #loop for every line
    while True:
        #puts the next 3 words into a string
        temp = " ".join(listOfWords[i:i+3])
        #check new length of line after adding the new 3 words, if it is still less than 70, add the words, otherwise break out of the loop
        if len(line) + len(temp) > 70:
            break
        line += "{} ".format(temp)
        i+=3
    #remove finished words from the list completely
    listOfWords = listOfWords[i:]
    #adds line into result list
    lines.append(line.strip())

#to make sure this works
for line in lines:
    print len(str(line))
    print "Number of words: {}".format(len(line.split()))
    print "number of chars: {}".format(len(line))
    print line
    print "----------------------------------------"

---

一个字符串中的总字数可以被3整除。我会把你的字符串分成几个字，然后针对每个字，测试它是否会使当前句子过长。如果是这样，冻结当前句子，并将该单词作为下一行的开头。

import sys
#long string; 84 words; divisible by 3
longString = "The charges are still sealed under orders from a federal judge. Plans were prepared Friday for anyone charged to be into custody as soon as Monday, the sources said. It is unclear what the charges are. A spokesman for the special counsel's office declined to comment. The White House also had no comment, a senior administration official said Saturday morning. A spokesman for the special counsel's office declined to comment. The White House also had no comment, a senior administration official said Saturday morning."
#convert string to list
listOfWords = longString.split()
#list to contain lines
lines = []
#make sure number of words is divisible by 3
if  len(listOfWords) % 3 != 0:
    #exit
    print "words number is not divisible by 3"
    sys.exit()
#keep going until list is empty
while listOfWords:

    i = 0
    line = ""
    #loop for every line
    while True:
        #puts the next 3 words into a string
        temp = " ".join(listOfWords[i:i+3])
        #check new length of line after adding the new 3 words, if it is still less than 70, add the words, otherwise break out of the loop
        if len(line) + len(temp) > 70:
            break
        line += "{} ".format(temp)
        i+=3
    #remove finished words from the list completely
    listOfWords = listOfWords[i:]
    #adds line into result list
    lines.append(line.strip())

#to make sure this works
for line in lines:
    print len(str(line))
    print "Number of words: {}".format(len(line.split()))
    print "number of chars: {}".format(len(line))
    print line
    print "----------------------------------------"