Question

下面是完整的代码，该代码将字典中的书面字符转换为乐谱。我想知道是否有人可以向我解释for循环的工作原理。

char2notes = { 
  ' ':("a4 a4 ", "r2 "),
  'a':("<c a>2 ", "<e' a'>2 "),
  'b':("e2 ", "e'4 <e' g'> "),
  'c':("g2 ", "d'4 e' "), 
  'd':("e2 ", "e'4 a' "),
  'e':("<c g>2 ", "a'4 <a' c'> "),
  'f':("a2 ", "<g' a'>4 c'' "),
  'g':("a2 ", "<g' a'>4 a' "),
  'h':("r4 g ", " r4 g' "),
  'i':("<c e>2 ", "d'4 g' "),
  'j':("a4 a ", "g'4 g' "),
  'k':("a2 ", "<g' a'>4 g' "),
  'l':("e4 g ", "a'4 a' "),
  'm':("c4 e ", "a'4 g' "),
  'n':("e4 c ", "a'4 g' "),
  'o':("<c a g>2  ", "a'2 "),
  'p':("a2 ", "e'4 <e' g'> "),
  'q':("a2 ", "a'4 a' "),
  'r':("g4 e ", "a'4 a' "),
  's':("a2 ", "g'4 a' "),
  't':("g2 ", "e'4 c' "),
  'u':("<c e g>2  ", "<a' g'>2"),
  'v':("e4 e ", "a'4 c' "),
  'w':("e4 a ", "a'4 c' "),
  'x':("r4 <c d> ", "g' a' "),
  'y':("<c g>2  ", "<a' g'>2"),
  'z':("<e a>2 ", "g'4 a' "),
  '\n':("r1 r1 ", "r1 r1 "),
  ',':("r2 ", "r2"),
  '.':("<c e a>2 ", "<a c' e'>2")
}

txt = "Love one another and you will be happy. It is as simple as that."

upper_staff = ""
lower_staff = "" 
for i in txt.lower():
    (l,u) = char2notes[i]
    upper_staff += u
    lower_staff += l

staff = "{\n\\new PianoStaff << \n"
staff += "  \\new Staff {" + upper_staff + "}\n"  
staff += "  \\new Staff { \clef bass " + lower_staff + "}\n"  
staff += ">>\n}\n"

title = """\header {
  title = "Love One Another"
  composer = "Bernd Klein using Python"
  tagline = "Copyright: Bernd Klein"
}"""

print (title + staff)

Answer 1

# Loop over the characters ("i") in txt.lower() - txt converted to lowercase.
for i in txt.lower():

    # Assign the values in the char2notes dictionary value corresponding to the key 
    # (the character within txt.lower()) to variables l and u.
    (l,u) = char2notes[i]

    # Append u to the upper_staff string
    upper_staff += u

    # Append l to the lower_staff string
    lower_staff += l

Answer 2

字符串实际上只是字符列表，因此您的for循环遍历字符串中的每个字符，找到与该字符对应的元组（或该字符为大写的小写字母），然后将元组的第一个元素附加到使用+ =运算符输入您的lower_staff字符串，并对第二个元素和upper_staff进行相同操作。

这个for循环有什么作用？ -乐谱

2 个答案: