blocks|key|3030268|text|一种方法是使用默认的line_terminator(\n)保存除最后一项之外的数据，并在最后一行后面附加line_terminator=""。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|3030269|data1+=+data.iloc[0:len(data)-1]
data2+=+data.iloc[[len(data)-1]]
data1.to_csv('csv_data',+sep=',',+encoding='utf-8',+header=+False,+index+=+False)
data2.to_csv('csv_data',+sep=',',+encoding='utf-8',+header=+False,+index+=+False,mode='a',line_terminator="")|code-block|syntax|javascript|3030270|entityMap^0|A|F|Q|2|1G|I|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]|$9|P|A|Q|B|C]|$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|T|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|U|8|@]|D|@]|E|$]]]|L|$]]

One way would be to save data except the last entry,with default <code>line_terminator</code>(<code>\n</code>) and append the last line with <code>line_terminator=""</code> .

<pre><code>data1 = data.iloc[0:len(data)-1]
data2 = data.iloc[[len(data)-1]]
data1.to_csv('csv_data', sep=',', encoding='utf-8', header= False, index = False)
data2.to_csv('csv_data', sep=',', encoding='utf-8', header= False, index = False,mode='a',line_terminator="")
</code></pre>

blocks|key|5145500|text|由于某些原因，当我尝试使用行终止符时，它无法工作。(它给出了一个错误，说line_terminator是一个无法识别的关键字参数。)|type|unstyled|depth|inlineStyleRanges|entityRanges|data|5145501|然而，这将会起到作用：|5145502|++++df.to_csv(path)
++++with+open(path)+as+f:
++++++++lines+=+f.readlines()
++++++++last+=+len(lines)+-+1
++++++++lines[last]+=+lines[last].replace('\r','').replace('\n','')
++++with+open(path,+'w')+as+wr:
++++++++wr.writelines(lines)|code-block|syntax|javascript|5145503|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|L|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|M|8|@]|9|@]|A|$G|H]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

For some reason, the line terminator did not work when I tried it. (It gave an error, saying line_terminator is an unrecognized keyword argument.) 

However, this will do the trick:

<pre><code> df.to_csv(path)
 with open(path) as f:
 lines = f.readlines()
 last = len(lines) - 1
 lines[last] = lines[last].replace('\r','').replace('\n','')
 with open(path, 'w') as wr:
 wr.writelines(lines)
</code></pre>

blocks|key|2138017|text|file_out+=+r'c:\your_output_file_path\file_name.csv'
df.to_csv(file_out)
file_data+=+open(file_out,+'rb').read()
open(file_out,+'wb').write(file_data[:-2])|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|2138018|df.to_csv()函数有一个名为line_terminator的参数，默认值为'\n‘。这个新行字符就是手头的问题。|unstyled|2138019|上面的代码：|2138020|1)正常将数据帧写入文件|2138021|2)打开文件并将字节数据读入file_data变量|2138022|3)将file_data变量写回同一个文件，但使用拼接:+file_data:-2修剪掉'\n‘|2138023|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|R|8|@]|9|@]|A|$]]|$1|G|3|H|5|F|7|S|8|@]|9|@]|A|$]]|$1|I|3|J|5|F|7|T|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|U|8|@]|9|@]|A|$]]|$1|M|3|N|5|F|7|V|8|@]|9|@]|A|$]]|$1|O|3|-4|5|F|7|W|8|@]|9|@]|A|$]]]|P|$]]

<pre><code>file_out = r'c:\your_output_file_path\file_name.csv'
df.to_csv(file_out)
file_data = open(file_out, 'rb').read()
open(file_out, 'wb').write(file_data[:-2])
</code></pre>

df.to_csv() function has a parameter called line_terminator with a default value of '\n'. This new line character is the issue at hand. 

The code above: 
1) writes the dataframe to file as normal 
2) opens the file and reads in the bytes data to the file_data variable 
3) writes the file_data variable back out to the same file but trims off the '\n' with the splice: file_data[:-2]

blocks|key|5146297|text|一种解决方案是不使用pandas将数据导出到文件。下面的示例不会在文件末尾包含空行。然而，它可能比熊猫的"to_csv“方法慢得多。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|5146298|import+pandas+as+pd

def+export_dataframe_to_file(+
++++++++df:+pd.DataFrame,+file_name:+str,+
++++++++header=True,+index=True,+delimiter=',',
++++++++line_terminator='\n',+encoding='utf-8'+
++++++++)+->+None:
++++'''
++++This+function+exports+a+Pandas+DataFrame+to+a+file+without
++++including+an+empty+row+at+the+very+end+of+the+file.
++++'''
++++number_of_rows,+current_row+=+len(df),+1
++++with+open(file_name,+'w',+encoding=encoding)+as+file+:
++++++++if+header:
++++++++++++file.write(+
++++++++++++++++delimiter*index+%2B+delimiter.join(df.columns)+\
++++++++++++++++%2B+line_terminator+
++++++++++++++++)
++++++++for+df_index,+series+in+df.iterrows():
++++++++++++file.write(+
++++++++++++++++(str(df_index)+%2B+delimiter)*index+\
++++++++++++++++%2B+delimiter.join(series.astype(+str+))+\
++++++++++++++++%2B+line_terminator*(not+not+number_of_rows+-+current_row)
++++++++++++++++)
++++++++++++current_row+%2B=+1
++++return|code-block|syntax|javascript|5146299|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

One solution is to not use pandas to export the data to a file. The example below will not include an empty row at the end of the file. However, it's probably a lot slower than pandas' &quot;to_csv&quot; method.
<pre><code>import pandas as pd

def export_dataframe_to_file( 
 df: pd.DataFrame, file_name: str, 
 header=True, index=True, delimiter=',',
 line_terminator='\n', encoding='utf-8' 
 ) -&gt; None:
 '''
 This function exports a Pandas DataFrame to a file without
 including an empty row at the very end of the file.
 '''
 number_of_rows, current_row = len(df), 1
 with open(file_name, 'w', encoding=encoding) as file :
 if header:
 file.write( 
 delimiter*index + delimiter.join(df.columns) \
 + line_terminator 
 )
 for df_index, series in df.iterrows():
 file.write( 
 (str(df_index) + delimiter)*index \
 + delimiter.join(series.astype( str )) \
 + line_terminator*(not not number_of_rows - current_row)
 )
 current_row += 1
 return
</code></pre>

blocks|key|3030420|text|上面的解决方案都不起作用，因为正如最初的问题所问的，他试图将文件发送到另一个不接受回车的脚本/REST+API。这很可能是由他用来将csv文件发送到REST+API的请求库引起的。我能够使用requests库通过REST+API发送一个带有回车符的文件：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3030421|import+requests
import+pandas+as+pd
import+settings


file_name+=+Hierarchy.csv'
df+=+pd.read_csv(file_name)
df.to_csv(file_name,+sep=',',+encoding='utf-8',+index=False)
headers+=+{
++'x-api-key':+settings.MONITOR_REST_API_KEY,
++'x-api-token':+settings.MONITOR_REST_API_TOKEN,
++'accept':+'application/json'
}

files+=+{'file':+(file_name,+open(file_name,+'rb'),+'text/csv')}
monitor_rest_url+=+"https://api.yourcloud.com"
response+=+requests.post(monitor_rest_url+%2B'/api/v2/your_endpoint',
++++++++++++++++++++++++files=files,+verify=False,+headers=headers)
print(response.text)|code-block|syntax|javascript|3030422|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

None of the solutions above worked because as the original question asked he was trying to send the file to another script/REST API that wouldn't accept carriage return. This is likely caused by the requests library he is using to send the csv file to the REST API. I was able to use the requests library to send a file which had a carriage return via REST API:
<pre><code>import requests
import pandas as pd
import settings


file_name = Hierarchy.csv'
df = pd.read_csv(file_name)
df.to_csv(file_name, sep=',', encoding='utf-8', index=False)
headers = {
 'x-api-key': settings.MONITOR_REST_API_KEY,
 'x-api-token': settings.MONITOR_REST_API_TOKEN,
 'accept': 'application/json'
}

files = {'file': (file_name, open(file_name, 'rb'), 'text/csv')}
monitor_rest_url = &quot;https://api.yourcloud.com&quot;
response = requests.post(monitor_rest_url +'/api/v2/your_endpoint',
 files=files, verify=False, headers=headers)
print(response.text)
</code></pre>

blocks|key|2138003|text|一种更有效的方法是首先打开文件，写入该流，然后删除最后一个换行符：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2138004|import+os
with+open('csv_data',+'wb')+as+dst:
++++data.to_csv(wb,+sep=',',+encoding='utf-8',+header=+False,+index+=+False)
++++dst.seek(-1,+os.SEEK_END)+#+<----+1+:+len('\n')
++++dst.truncate()|code-block|syntax|javascript|2138005|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

A more efficient way is to open the file first, write to that stream, then remove the last newline:

<pre><code>import os
with open('csv_data', 'wb') as dst:
 data.to_csv(wb, sep=',', encoding='utf-8', header= False, index = False)
 dst.seek(-1, os.SEEK_END) # &lt;---- 1 : len('\n')
 dst.truncate()
</code></pre>

When saving the data to csv, <code>data.to_csv('csv_data', sep=',', encoding='utf-8', header= False, index = False)</code>, it creates a blank line at the end of csv file. 

How do you avoid that? 

It's got to do with the <code>line_terminator</code> and it's default value is <code>n</code>, for new line.

Is there a way to specify the <code>line_terminator</code> to avoid creating a blank line at the end, or do i need to read the csv file, remove the blank line and save it?

Not familiar with pandas. Your help will be appreciated, thanks in advance!

How to stop writing a blank line at the end of csv file - pandas

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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当将数据保存到csv，data.to_csv('csv_data', sep=',', encoding='utf-8', header= False, index = False)时，它会在csv文件的末尾创建一个空行。你如何避免这种情况呢？它与line_terminator有关，对于新行，它的默认值是n。有没有办法指定line_terminator以避免在结尾创建空行，或者我是否需要读取csv

问如何停止在csv文件末尾写入空行- pandas
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问如何停止在csv文件末尾写入空行- pandas
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