import csv
with open('thefile.csv', 'rb') as f:
data = list(csv.reader(f))
import collections
counter = collections.defaultdict(int)
for row in data:
counter[row[10]] += 1
with open('/pythonwork/thefile_subset11.csv', 'w') as outfile:
writer = csv.writer(outfile)
for row in data:
if counter[row[10]] >= 504:
writer.writerow(row)
这段代码读取file.csv，进行修改，并将结果写入到file_subset1。
然而，当我在Microsoft Excel中打开结果csv时，每条记录后都有一个额外的空行!
有没有办法让它不放额外的空行?
当前回答
with open(destPath+'\\'+csvXML, 'a+') as csvFile:
writer = csv.writer(csvFile, delimiter=';', lineterminator='\r')
writer.writerows(xmlList)
lineterminator='\r'"允许传递到下一行，两行之间没有空行。
其他回答
从最初的问题开始的十年里，许多其他的答案都已经过时了。对于Python3，答案在文档中是正确的:
如果csvfile是一个文件对象，它应该用newline= "
脚注更详细地解释了:
如果没有指定newline= "，则内嵌在带引号字段中的换行符将不能被正确解释，并且在write时使用\r\n linend的平台上将添加一个额外的\r。指定newline= "应该总是安全的，因为csv模块有自己的(通用的)换行处理。
使用下面定义的方法将数据写入CSV文件。
open('outputFile.csv', 'a',newline='')
只需在open方法中添加一个额外的newline= "参数:
def writePhoneSpecsToCSV():
rowData=["field1", "field2"]
with open('outputFile.csv', 'a',newline='') as csv_file:
writer = csv.writer(csv_file)
writer.writerow(rowData)
这将写入CSV行，而无需创建额外的行!
我将这个答案w.r.t.写入python 3，因为我最初遇到了相同的问题。
我应该使用PySerial从arduino获取数据，并将它们写入.csv文件中。在我的例子中，每次读取都以'\r\n'结束，因此换行符总是分隔每行。
在我的例子中，newline= "选项不起作用。因为它显示了一些错误，比如:
with open('op.csv', 'a',newline=' ') as csv_file:
ValueError: illegal newline value: ''
所以他们似乎不接受省略换行符。
只在这里看到一个答案，我提到了writer对象中的行结束符，比如，
Writer = csv。Writer (csv_file, delimiter=' '，lineterminator='\r')
这对我跳过额外的换行很有效。
注意:这似乎不是首选的解决方案，因为在Windows系统上是如何添加额外的行。如python文档中所述:
如果csvfile是一个文件对象，在不同的平台上，它必须用' b '标志打开。
Windows is one such platform where that makes a difference. While changing the line terminator as I described below may have fixed the problem, the problem could be avoided altogether by opening the file in binary mode. One might say this solution is more "elegent". "Fiddling" with the line terminator would have likely resulted in unportable code between systems in this case, where opening a file in binary mode on a unix system results in no effect. ie. it results in cross system compatible code.
来自Python文档:
On Windows, 'b' appended to the mode opens the file in binary mode, so there are also modes like 'rb', 'wb', and 'r+b'. Python on Windows makes a distinction between text and binary files; the end-of-line characters in text files are automatically altered slightly when data is read or written. This behind-the-scenes modification to file data is fine for ASCII text files, but it’ll corrupt binary data like that in JPEG or EXE files. Be very careful to use binary mode when reading and writing such files. On Unix, it doesn’t hurt to append a 'b' to the mode, so you can use it platform-independently for all binary files.
原:
作为csv可选参数的一部分。如果你得到额外的空行，你可能不得不改变行结束符(信息这里)。下面的例子改编自python页面csv docs。把“\n”改成它应该是什么样子。因为这只是在黑暗中对问题的一种尝试，这可能行得通，也可能行不通，但这是我最好的猜测。
>>> import csv
>>> spamWriter = csv.writer(open('eggs.csv', 'w'), lineterminator='\n')
>>> spamWriter.writerow(['Spam'] * 5 + ['Baked Beans'])
>>> spamWriter.writerow(['Spam', 'Lovely Spam', 'Wonderful Spam'])
我使用writerow
def write_csv(writer, var1, var2, var3, var4):
"""
write four variables into a csv file
"""
writer.writerow([var1, var2, var3, var4])
numbers=set([1,2,3,4,5,6,7,2,4,6,8,10,12,14,16])
rules = list(permutations(numbers, 4))
#print(rules)
selection=[]
with open("count.csv", 'w',newline='') as csvfile:
writer = csv.writer(csvfile)
for rule in rules:
number1,number2,number3,number4=rule
if ((number1+number2+number3+number4)%5==0):
#print(rule)
selection.append(rule)
write_csv(writer,number1,number2,number3,number4)
