how to save data during about 1000 simulations times

[Nissa wang]

I'm working on a simulation,now i want to record  a data in about 1000 time.How can I record them into a file.

[Tommaso Pecorella]

I promised to be calm and to not mock people. Sometimes I think it's harder than quit smoking.

On Saturday, April 5, 2014 3:13:58 PM UTC+2, Nissa wang wrote:

I'm working on a simulation,now i want to record  a data in about 1000 time.How can I record them into a file.

Read the tutorial. Read the manual. Open a file. Write stuff in the file.

In the examples there are many... examples (oh, rly?) with periodic functions.

[Nissa wang]

OK，I know the logging or Tracing files to use. But my question is different.I am not write many value to a files in a simulations.

what  i do was record a data value in  a file in about 1000 times. The value in the logging or Tracing  files is always overwrited by the new simulation. How can I save 1000 times' simulations values in  file?

在 2014年4月6日星期日UTC+8上午12时50分38秒，Tommaso Pecorella写道：

[Ivo Calado]

Nissa,

   a simple workaround would be you save the logs of each simulation of a different file, where the filename you pass as an argument.

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Ivo Calado

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Putt's Law:
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[Konstantinos]

You just need to tell that the file will be the same and data will be APPENDED each time, not write over.

Depending on how you create/write to the file, there is a different way to accomplish that.

[Nissa wang]

OK,thank you very much for your reply.but the method you propose is not suited in my simulation. For every simulation time,i just want write a value obtained during simualtion to the file. If i use different filenames,it will be a nightmare for me to open about 1000 files to copy a value everytime.

在 2014年4月6日星期日UTC+8上午2时26分12秒，Ivo Calado写道：

[Nissa wang]

then,how can i have the data appended ,not write over everyime.For the logging and tracing are always write over in different independent simulations.

在 2014年4月6日星期日UTC+8上午2时30分57秒，Konstantinos写道：

[Konstantinos]

On Saturday, April 5, 2014 7:36:23 PM UTC+1, Nissa wang wrote:

OK,thank you very much for your reply.but the method you propose is not suited in my simulation. For every simulation time,i just want write a value obtained during simualtion to the file. If i use different filenames,it will be a nightmare for me to open about 1000 files to copy a value everytime.

You can use a bash script to read files in a loop.

[Tommaso Pecorella]

LMGIFY (feel free to google the acronym)

http://www.cplusplus.com/doc/tutorial/files/

T.

[Nissa wang]

Hi Tommaso,

Thanks very much for the link you show to me. And it's very helpful. The following is the c++ and python script i used to control writing data value to a file in seeral simulations.

1.  ofstream myfile;

    myfile.open ("example.txt",ios::out | ios::app | ios::binary);

   myfile <<time_value<< ",\n";

    myfile.close();

2.#!/usr/bin/python

import sys

import os

#define function

def start_simulation(data):

os.system('./waf --run "scratch/newadhoc --RngRun=%d" ' % (data))

for rng in range(1,6):

start_simulation(rng)

print '#%d' % (rng)

3.the value in the example.txt.the value of time_value in 1.

30.061,

30.0125,

30.0366,

30.0156,

30.0734,

在 2014年4月6日星期日UTC+8上午4时12分03秒，Tommaso Pecorella写道：

[Nissa wang]

Thank you for your help.As for as i don not know how to read files in a loop, i used " ofstream myfile" provided by  Tommaso Pecorella. Finally,problem was solved.

Thank you for your both.

在 2014年4月6日星期日UTC+8上午4时05分52秒，Konstantinos写道：

[Ivo Calado]

Nissa, I missunderstood your question. I though you wanted to save a lot of data on each simulation. As Tommaso said, you can use ofstream to output data directly to a file or you can flush data to the stderr or stdout and redirect the data from outside of simulation program.

Ex.:
./waf --run "simulation" >> file (appends the output from stdout into file)
./waf --run "simulation" 2>> file (appends the output from stderr into file)

Cheers,

   Ivo