在`python`中对同一个变量使用多个条件

Question

我的数据如下所示（4 列和制表符分隔）：

AAA 123 null    0
AAA 124 null    1
BBB 234 null    0
CCC 235 negative    -2
CCC 345 negative    2
DDD 346 null    -1
EEE 456 positive    4
EEE 457 positive    0

使用这些数据，我需要编写一个条件语句，如果满足第 3 列和第 4 列中的两个条件，则在第 5 列打印单词“TRUE”，否则打印单词“FALSE” .

尝试使用python 嵌套“IF”语句，我编写了以下代码：

with open('infile.input', "r") as opened_file:
    for gLine in opened_file:
        print gLine
        oneID, twoID, oneScore, twoScore = gLine.split()
        if oneScore == "positive" and twoScore > 0:
            if oneScore == "null" and twoScore == 0:
                if oneScore == "neutral" and twoScore == 0:
                    if oneScore == "negative" and twoScore < 0:
                        print oneID, twoID, oneScore, twoScore, "TRUE"
        else:
            print oneID, twoID, oneScore, twoScore, "FALSE"

这段代码的结果是“FALSE”分配给所有的行，如下：

AAA 123 null    0   FALSE
AAA 124 null    1   FALSE
BBB 234 null    0   FALSE
CCC 235 negative    -2  FALSE
CCC 345 negative    2   FALSE
DDD 346 null    -1  FALSE
EEE 456 positive    4   FALSE
EEE 457 positive    0   FALSE

。我查看了here 和here 以寻求解决问题的建议，并且代码仅适用于一种条件（例如，将所有“肯定”和“x>0”正确标记为 TRUE）。当我添加多个条件时，它无法达到我想要的结果，如下所示：

AAA 123 null    0   TRUE
AAA 124 null    1   FALSE
BBB 234 null    0   TRUE
CCC 235 negative    -2  TRUE
CCC 345 negative    2   FALSE
DDD 346 null    -1  FALSE
EEE 456 positive    4   TRUE
EEE 457 positive    0   FALSE

使用下面的建议，我尝试实现这一点，它只能正确找到第一个条件的情况。所有其他条件，无论它们是否为真，都被标记为假。我怎样才能让它识别所有 4 个条件？

if  ((oneScore == "positive" and twoScore > 0) or
         (oneScore == "null" and twoScore == 0) or
         (oneScore == "neutral" and twoScore == 0) or
         (oneScore == "negative" and twoScore < 0)):
        print oneID, twoID, oneScore, twoScore, "TRUE"
    else:
        print oneScore, twoScore, "FALSE"

Answer 1

这个怎么样：

print bookID, ID, oneScore, twoScore, (oneScore == "positive" and twoScore > 0) \
    or (oneScore == "null" and twoScore == 0) \
    or (oneScore == "negative" and twoScore < 0)

Answer 2

您应该使用 if-elif 而不是嵌套 if，从您的代码中，它永远不会打印 'TRUE'

正确的逻辑应该是这样的

if oneScore == 'positive' and int(twoScore) > 0:
     print bookID, ID, oneScore, twoScore, "TRUE"

elif (oneScore == 'neutral' or oneScore == 'null') and int(twoScore) == 0:
    print bookID, ID, oneScore, twoScore, "TRUE"

elif oneScore == 'negative' and int(twoScore) < 0:
    print bookID, ID, oneScore, twoScore, "TRUE"

else:
    print bookID, ID, oneScore, twoScore, "FALSE"

Answer 3

类似的东西呢：

twoScore = int(twoScore)
cases = [
    oneScore == "positive" and twoScore > 0,
    oneScore == "null" and twoScore == 0,
    oneScore == "neutral" and twoScore == 0,
    oneScore == "negative" and twoScore < 0
]
state = any(cases) and "TRUE" or "FALSE"

它应该将您的数据与您的逻辑分开并简化代码的维护。

Answer 4

听起来您想要or，而不是嵌套的if 语句。您测试的所有条件都不可能同时为真，因此嵌套的ifs（在这种情况下类似于and）永远不会全部通过，让您的代码打印True .

试试：

if  ((oneScore == "positive" and twoScore > 0) or
     (oneScore == "null" and twoScore == 0) or
     (oneScore == "neutral" and twoScore == 0) or
     (oneScore == "negative" and twoScore < 0)):
    print bookID, ID, oneScore, twoScore, "TRUE"

twoScore 的比较仍然会出现问题，因为在您从文件中读取的行之后，split 将是一个字符串。在进行比较之前，您需要在某个时间点调用int。