Python语句中的语法无效

Question

我正在尝试运行下面的代码，当我运行python tfidf.py（Python 2.6.9）时，我在下面的行中出现SyntaxError: invalid syntax错误，指向for语句。我做错了什么？

def produceVector(blob, bloblist):
    ##### SYNTAXERROR: invalid syntax in the "for" in the line below #####
    scores = {word: tfidf(word, blob, bloblist) for word in blob.words}
    return scores

def tf(word, blob):
    return blob.words.count(word) / len(blob.words)

def n_containing(word, bloblist):
    return sum(1 for blob in bloblist if word in blob)

def idf(word, bloblist):
    return math.log(len(bloblist) / (1 + n_containing(word, bloblist)))

def tfidf(word, blob, bloblist):
    return tf(word, blob) * idf(word, bloblist)

Answer 1

这不是一个声明，这是一个词典理解。这只是在2.7中引入的。生成一个可迭代的2元组，并将其传递给dict()构造函数。

Answer 2

a = [3, 2, 1, 0]
d = {i: a[i] for i in a}        # python > 2.6
e = dict((i, a[i]) for i in a)  # python <= 2.6 
print e == d