Question

请参阅以下代码 -

from sys import argv
from urllib2 import urlopen
from os.path import exists

script, to_file = argv

url = "http://numbersapi.com/random"

fact = 0
number = 0

print "Top 5 Facts of The World"

while fact < 5:
    response = urlopen(url)
    data = response.read()
    fact += 1
    number += 1
    print
    print "%s). %s " % (str(number), data)

print "Now, let us save the facts to a file for future use."
print "Does the output file exist? %r" % exists(to_file)
print "When you are ready, simply hit ENTER"
raw_input()
out_file = open(to_file, 'w')
out_file.write(data)
print "Alright, facts are saved in the repo."
out_file.close()

上面代码中的问题是当我打开file1.txt时，我看到只打印了1个事实。作为一种变体，我将所有内容都带入了while循环中。它导致了同样的问题。我认为它写了一个事实，但随后用下一个和下一个覆盖，直到最后一个事实被保存。

我做错了什么？

Answer 1

“data”仅包含分配给它的最后一个值。

from sys import argv

script, to_file = argv

fact = 0
number = 0

out_file = open(to_file, 'w')
while fact < 5:
    data = str(fact)
    out_file.write(str(data) + '\n')
    fact += 1
    number += 1
    print
    print "%s). %s " % (str(number), data)
out_file.close()

Answer 2

每次循环迭代都会覆盖data。试试这个：

out_file = open(to_file, 'w')
while fact < 5:
    response = urlopen(url)
    data = response.read()
    fact += 1
    number += 1
    print
    print "%s). %s " % (str(number), data)
    out_file.write(data)
    out_file.write('\n') #one fact per line

out_file.close()

Answer 3

看起来你正在覆盖循环上的数据，所以最后你只有最后的数据。尝试改变这样的事情：

[...]
final_data=''
while fact < 5:
    response = urlopen(url)
    data = response.read()
    fact += 1
    number += 1
    print
    print "%s). %s " % (str(number), data)
    final_data+=data

[...]
out_file.write(final_data)

Answer 4

问题是您在循环之后写入文件，以便data指向最后获取的url数据。要解决此问题，请将data存储在列表中，然后从列表中写下所有内容，如下所示：

for fact in data: out_file.write(fact + '\n')

你需要追加这样的事实：

data.append(response.read())

或者询问是否要在获取事实之前将其写入文件，然后移动文件操作：

with open(to_file, 'wb') as out_file: while fact < 5: response = urlopen(url) data = response.read() if should_write: out_file.write(data + '\n') fact += 1 number += 1 print print "%s). %s " % (str(number), data)

如何在Python中按顺序将多行写入文件

4 个答案: