python中的循环不会遍历文件中的每一行
python中的循环不会遍历文件中的每一行
提问于 2017-02-07 00:56:18
我正在尝试遍历文本文件中的每一行并执行一些操作。现在，我有一个文本文件，其中包含以下内容：
--- small modified --- #line 1
1,2,3 #line 2
4,5,6 #line 3
--- big modified --- #line 4
7;8;9 #line 5
10;11;12 #line 6我试图将第2,3行解析为一个文件，将第5,6行解析为另一个文件，但现在，只有第2行和第3行被写入文件中，并解释了为什么没有运行"elif“语句。我无法解决逻辑错误，如果有人能帮助我，我将不胜感激。
下面是我的代码：
def convert_json(fileName):
with open(fileName,'r') as file:
for line in file:
if 'modified' and 'small' in line:
for li in file:
fields1 = li.split(',')
if len(fields1) >= 3:
smallarr.append({
"a": fields1[0],
"b": fields1[1],
"c": fields1[2]
})
with open('smalljson.txt','w+') as small_file:
json.dump(smallarr, small_file)
else:
pass
elif 'modified' and 'big' in line:
for li in file:
fields2 = li.split(';')
if len(fields2) >= 3:
bigarr.append({
"w1": fields2[0],
"w2": fields2[1],
"w3": fields2[2],
})
with open('big.txt','w+') as big_file:
json.dump(bigarr, big_file)
else:
pass
else:
print 'test'更新: THis是我当前的代码，我只能在第2行和第5行这样做，除了第二个for循环之外，我想不出其他方法来遍历这些行。
def convert_json(fileName):
with open(fileName,'r') as file:
for line in file:
#if 'modified' in line and 'small' in line:
if 'modified' in line and 'Small' in line:
fields1 = next(file).split(',')
if len(fields1) >= 3:
smallarr.append({
"a": fields1[0],
"b": fields1[1],
"c": fields1[2]
})
with open('smalljson.txt','w+') as small_file:
json.dump(smallarr, small_file)
else:
pass
elif 'modified' in line and 'big' in line:
fields2 = next(file).split(';')
if len(fields2) >= 3:
bigarr.append({
"w1": fields2[0],
"w2": fields2[1],
"w3": fields2[2],
})
with open('bigwater.txt','w+') as big_file:
json.dump(bigarr, big_file)
else:
pass
else:
print 'test'回答 3
Stack Overflow用户
回答已采纳
发布于 2017-02-07 01:43:21
您的解析逻辑需要更改。下面是代码的样子，在以后的改进中可以参考它。
def file_parser(self):
file_section = 0
smallarr = []
bigarr = []
with open('data.txt') as in_file:
for in_line in in_file:
in_line = in_line.strip()
if 'small' in in_line:
file_section = 1
continue
elif 'big' in in_line:
file_section = 2
continue
if file_section == 1:
fields1 = in_line.split(',')
if len(fields1) >= 3:
smallarr.append({
"a": fields1[0],
"b": fields1[1],
"c": fields1[2]
})
elif file_section == 2:
fields2 = in_line.split(';')
if len(fields2) >= 3:
bigarr.append({
"w1": fields2[0],
"w2": fields2[1],
"w3": fields2[2],
})
with open('small.txt', 'w+') as small_file:
json.dump(smallarr, small_file)
with open('big.txt', 'w+') as big_file:
json.dump(bigarr, big_file)输入数据：
--- small modified ---
1,2,3
4,5,6
--- big modified ---
7;8;9
10;11;12small.txt
[{"a": "1", "c": "3", "b": "2"}, {"a": "4", "c": "6", "b": "5"}]big.txt
[{"w3": "9", "w2": "8", "w1": "7"}, {"w3": "12", "w2": "11", "w1": "10"}]Stack Overflow用户
发布于 2017-02-07 01:00:17
变化
elif 'modified' and 'big' in line:转到
elif 'modified' in line and 'big' in line:Stack Overflow用户
发布于 2017-02-07 02:06:30
您的代码中存在一些问题。
首先，你在重复你自己。大的和小的情况没有足够的差异来证明代码重复。
其次，虽然我知道你想用next(file)做什么，但你仍然需要以某种方式循环这条指令来获取下一行代码。但是等等，你已经在用for line in file做同样的事情了。
最后，在每个循环中，您将重新打开相同的文件并重新生成一个不断增加的数组。这是浪费的IO。如果您试图从file流式传输到bigwater.txt和smalljson.txt中，并且没有在内存中存储太多内容，那么这种方法是错误的，因为json.dump不能用于流式传输数据。
以下是我对此的看法：
def convert_json(fileName):
big = []
small = []
with open(fileName,'r') as file:
for line in file:
line = line.strip()
if line.startswith("--"):
if "big" in line:
array = big
keys = ["w1", "w2", "w3"]
sep = ";"
else:
array = small
keys = ["a", "b", "c"]
sep = ","
continue
values = line.split(sep)
# todo: make sure sizes match
mapping = dict(zip(keys, values))
array.append(mapping)
with open('smalljson.txt','w') as small_file:
json.dump(small, small_file)
with open('bigwater.txt','w') as big_file:
json.dump(big, big_file)页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/42073176
复制相关文章
相似问题
腾讯云开发者
