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?
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。
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)
csv。Writer模块直接控制行结束符,并直接将\r\n写入文件。在python3中,该文件必须以非翻译文本模式打开,参数为'w', newline= "(空字符串),否则在Windows上将写入\r\r\n,其中默认文本模式将每个\n转换为\r\n。
#!python3
with open('/pythonwork/thefile_subset11.csv', 'w', newline='') as outfile:
writer = csv.writer(outfile)
在Python 2中,使用二进制模式以'wb'而不是'w'模式打开outfile,以防止Windows换行符转换。Python 2在Unicode方面也有问题,需要其他变通方法来编写非ascii文本。如果你必须处理在Python 2上将Unicode字符串写入csv,请参阅下面的Python 2链接以及页面末尾的unicoderreader和UnicodeWriter示例,或者查看第三方unicodecsv模块:
#!python2
with open('/pythonwork/thefile_subset11.csv', 'wb') as outfile:
writer = csv.writer(outfile)
文档链接
https://docs.python.org/3/library/csv.html#csv.writer
https://docs.python.org/2/library/csv.html#csv.writer
借用这个答案,似乎最干净的解决方案是使用io.TextIOWrapper。我为自己解决了这个问题:
from io import TextIOWrapper
...
with open(filename, 'wb') as csvfile, TextIOWrapper(csvfile, encoding='utf-8', newline='') as wrapper:
csvwriter = csv.writer(wrapper)
for data_row in data:
csvwriter.writerow(data_row)
上面的答案与Python 2不兼容。为了具有兼容性,我认为只需要将所有的写入逻辑包装在if块中:
if sys.version_info < (3,):
# Python 2 way of handling CSVs
else:
# The above logic