TypeError：’float’对象不可迭代,Python列表

spectrum_mass[second] = [1.0, 2.0, 3.0]
spectrum_intensity[second] = [4.0, 5.0, 6.0]
spectrum_mass[first] = [1.0, 34.0, 35.0]
spectrum_intensity[second] = [7.0, 8.0, 9.0]

for i in spectrum_mass[second]:
    if i not in spectrum_mass[first]:
        spectrum_intensity[first].extend(spectrum_intensity[second][spectrum_mass[second].index(i)])
        spectrum_mass[first].extend(i)

但是,当我尝试这样做时,我得到TypeError：’float’对象不可迭代
 在第3行.

为了清楚起见,spectrum_mass [second]是一个列表(在字典中,第二个和第一个是键),如spectrum_intensity [first],spectrum_intensity [second]和spectrum_mass [second].所有列表都包含浮点数.

spectrum_intensity[first].extend(spectrum_intensity[second][spectrum_mass[second].index(i)])

extend()函数需要一个可迭代的,但是你试图给它一个浮点数.在一个非常小的例子中相同的行为 –

>>> l = [1,2]
>>> l.extend(1.2)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'float' object is not iterable

你想使用.append()代替 –

spectrum_intensity[first].append(spectrum_intensity[second][spectrum_mass[second].index(i)])

同样的问题也在下一行中,使用append()而不是extend() –

spectrum_mass[first].extend(i)