How can I read a *.txt file from disk and display the values as bars in TChart

Unit1 · #1 30-Aug-2006, 16:42

Hi,

Can anyone help me with the following problem:

I have to read values from a DetectorLowEnergyGainMap.txt file on the disk that is filled with values like: -128,-10,-30,0, -200 etc. I can read the file with the following code:

CPP / C++ / C Code:

char LowEnergyGainMap[300]; 


bool TMainForm::LeesDetectorLowEnergyGainMap()
{
fstream inputfile;

          inputfile.open("DetectorLowEnergyGainMap.txt"); // 

          	FileName = ExtractFileName(OpenDialog->FileName);
          	SourceFileDir = ExtractFileDir(OpenDialog->FileName);

          		if(!inputfile) {
                	UpDateStatusLine(StatusLineRight,"Detector data file niet geladen !!!");
                	return FALSE;
          		}

          		while(!inputfile.eof()) {
                	inputfile.getline(LowEnergyGainMap, sizeof(LowEnergyGainMap));
          		}
	
          inputfile.close();

          UpDateStatusLine(StatusLineRight,FileName + "  data file geladen !!!");
       return TRUE;
}

So far, everything works fine. If I display the data e.x. with ShowMessage(LowEnergyGainMap) I can see that my array LowEnergyGainMap is filled now with the correct data.

However, if I try to display the data in a TChart with the code below, all the bars are displayed as positive bars and not with the data that is in the LowEnergyGainMap.

CPP / C++ / C Code:


if(WhichRange == "NR"){
 for (t=0; t<NumberOfTubes; t++) {  // Normal Range
      PMTGainNRDet1->Add(LowEnergyGainMap,t+1,GetDefaultColor(16));
}

I know that in the call: Add(LowEnergyGainMap,t+1,GetDefaultColor(16)) LowEnergyGainMap should be declared const double. I think that my problem resides here.

So, in general, how can I read the datavalues from my text file and display them as bars in the TChart.

Any suggestions are very welcome. Thanks in advance

Johan Ditzel

ubergeek · #2 31-Aug-2006, 10:29

I have no experience with TChart...but you are reading LowEnergyGainMap as a char array, i.e. a string containing the numbers in the file. You will have to use strtol() or something similar to convert them to doubles.

WaltP · #3 31-Aug-2006, 11:50

Quote:

Originally Posted by ubergeek

I have no experience with TChart...but you are reading LowEnergyGainMap as a char array, i.e. a string containing the numbers in the file. You will have to use strtol() or something similar to convert them to doubles.

Or better yet write your own function that splits the line into it's components.

Also, this loop

CPP / C++ / C Code:

while(!inputfile.eof()) 
{
    inputfile.getline(LowEnergyGainMap, sizeof(LowEnergyGainMap));
}

has 2 problems:
1) it reads each line of the file but does nothing with it. You therefore exit the loop with only the last line of the file as data. You need to process the line after reading.
2) you use .eof() to exit the loop. This is the same as using feof() in C. This won't work as you expect, and here's why

Unit1 · #4 01-Sep-2006, 02:17

Thanks for the reply and help. Now I am able to read my text file and display the values as bars in TChart. Here is the way I modified my code.

I did not change annything in the code below.

CPP / C++ / C Code:

char LowEnergyGainMap[300];
int PMTGainDataNR[60]; 


bool TMainForm::LeesDetectorLowEnergyGainMap()
{
fstream inputfile;

          inputfile.open("DetectorLowEnergyGainMap.txt"); // 

          	FileName = ExtractFileName(OpenDialog->FileName);
          	SourceFileDir = ExtractFileDir(OpenDialog->FileName);

          		if(!inputfile) {
                	UpDateStatusLine(StatusLineRight,"Detector data file niet geladen !!!");
                	return FALSE;
          		}

          		while(!inputfile.eof()) {
                	inputfile.getline(LowEnergyGainMap, sizeof(LowEnergyGainMap));
          		}
	
          inputfile.close();

          UpDateStatusLine(StatusLineRight,FileName + "  data file geladen !!!");
       return TRUE;
}

In the following function I added a loop that reads the gainmap with chars and converts it to a map with integers so that Tchart can display it.

CPP / C++ / C Code:

void __fastcall TMainForm::DetNRClick(TObject *Sender)
{

long getal;
char * pEnd;
char * s;
int z;

          OpenDialog->Filter = "Normal Range|*LowEnergy*.txt";
          if (OpenDialog->Execute()) {


          if(LeesDetectorLowEnergyGainMap()) {
                ShowMessage(LowEnergyGainMap);  // for debug only
                }

                s =  LowEnergyGainMap;

                for (z=0; z<NumberOfTubes+1; ++z) {
                        PMTGainDataNR[z] = strtol (s,&pEnd,0);  //strtol(nptr, (char **)NULL, 10);
                        s = pEnd+1;
                        }

          DisplayDetectorGainBars("NR");
          GainChart->Visible = TRUE;
          NRLoaded = TRUE;
          DetNR->Enabled = FALSE;

          }
          if(NRLoaded && ERLoaded){
                PMTGainDifference->Visible = TRUE;
                DisplayDetectorGainDifferenceMap();
                }
}

Thanks,

Johan

WaltP · #5 01-Sep-2006, 03:39

Your formatting needs an overhaul. Indenting just to indent is not a good idea. Check out this info for formatting ideas.

I still want to know what's going on here in this (reformatted) function:

CPP / C++ / C Code:

char LowEnergyGainMap[300];
int PMTGainDataNR[60]; 


bool TMainForm::LeesDetectorLowEnergyGainMap()
{
    fstream inputfile;

    inputfile.open("DetectorLowEnergyGainMap.txt"); // 

    FileName = ExtractFileName(OpenDialog->FileName);
    SourceFileDir = ExtractFileDir(OpenDialog->FileName);

    if(!inputfile) 
    {
        UpDateStatusLine(StatusLineRight,"Detector data file niet geladen !!!");
        return FALSE;
    }

    while(!inputfile.eof()) 
    {
        inputfile.getline(LowEnergyGainMap, sizeof(LowEnergyGainMap));
    }
	
    inputfile.close();

    UpDateStatusLine(StatusLineRight,FileName + "  data file geladen !!!");
    return TRUE;
}

Since you didn't change this function, what is its purpose? It reads the file, does nothing with any of the data read, and exits the read loop wrong (as my previous post explains). Am I missing something?

Unit1 · #6 01-Sep-2006, 04:24

Hi WaltP,

Thks for the quick response. Since I am a beginner in C/C++ I apreciate yr comments and help. I will check yr info about formatting ideas.

In the function LeesDetectorLowEnergyGainMap() I only read the contens of the file on disk and put it in an array of chars named LowEnergyGainMap.

In the next function DetNRClick I read the contens of LowEnergyGainMap and convert the chars into int's so that I can call TChart.

Now, I tried to read another file from disk and putting it in an array but if I read the array and tried to output its contens nothing is displayed. It has probably to do with explanation of yr previous post.

I will tried to change it and let you know.

Thanks

Johan

Unit1 · #7 06-Sep-2006, 09:03

Hi all,

I have the following question:

With fgets(EnergyMap, sizeof(EnergyMap), fp), I am reading a line from a Text file from disk.

The line of chars (a string) in the textfile look like this:

e.g.

5 \t 923.000000 \t 10.000000 \n

So 5 a TAB 923.000000 a TAB 10.000000 a carrage return.

Now I have to decode the string so that I can fill an array with the first number (in this case the 5), an array with the second number (923.000000 ) and an array with the last number (10.000000 ). The file contains 1000 lines.

So far I am able to decode the first number (5) and the last number (10.000000), however how can I decode (isolate) the second number, in this case 923.000000 from the string.

Here is a part of the code I use to decode the string:

CPP / C++ / C Code:


while ( fgets(EnergyMap, sizeof(EnergyMap), fp) != NULL) // ReturnCode == NULL wanneer er en fout ontstaat. The EOF is considered to be an ERROR!
              {
                 ch=strchr(EnergyMap,'\t');
                 TabPos = (int)(ch-EnergyMap+1);

                 if ( TabPos == 2 ) // Read the lines 1-9
                    {
                       while (ch != NULL)         // next two tabs
                          {
                              if((int)(ch-EnergyMap+1) == 2) // first tab
                                {
                                  ShowMessage((ch)); // Debug only
                                }

                               if((int)(ch-EnergyMap+1) > 10) // next tab
                                 {
                                   ShowMessage((ch)); // Debug only
                                   dbl = strtod (ch,&pEnd);
                                   ShowMessage((dbl)); // Debug only
                                 }
                            ch=strchr(ch+1,'\t');
                         }

                     positie[TabIndex] = TabIndex;
                     TabIndex++;
                  }

Thanks in advance,

Johan

WaltP · #8 06-Sep-2006, 09:30

If there are only two tabs on the line, you could do something much simpler.

Code:

while (fgets...)
{
    process first field
    get first tab position (as you did)
    process second field
    get second tab position
    process third field
}

If your data lines may contain errors, you'll have to add error processing.
If some lines are more complex than this, you may have to adjust your processing and this idea may not work well.

Unit1 · #9 07-Sep-2006, 04:24

I have to read and convert individual charcters to an int and double, like this:

EnergyMap contains characters like:

EnergyMap[0]contains a 1
EnergyMap[1]contains a 2
EnergyMap[2]contains a 3
EnergyMap[3]contains a 4

I have to read/convert the contens of EnergyMap[0 - 3]to an integer or double value like 1234.

The idea was first concatenate the 4 characters to a string and then convert it to an integer or double.

CPP / C++ / C Code:

char EnergyMap[4];
char str[10];

strcpy (str,EnergyMap[0]);
strcat (str,EnergyMap[1]);
strcat (str,EnergyMap[2]);
strcat (str,EnergyMap[3]);

But, the compiler is generating the error:

[C++ Error] Main.cpp(791): E2034 Cannot convert 'int' to 'const char *'

So, how can I read the individual characters from the array of chars and convert it to one integer or double value.

Any idea how to solve this??

Thanks in advance.

Johan

ubergeek · #10 07-Sep-2006, 15:12

strcat takes a whole string as the second parameter; you only have a single character. in this case, you can just assign str (which only needs to have 5 elements) the elements of EnergyMap directly.

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search
Rate This Thread
Rate This Thread:

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Apache2 config issues	monev	Apache Web Server Forum	2	28-Jun-2004 06:19

How can I read a *.txt file from disk and display the values as bars in TChart

Re: How can I read a *.txt file from disk and display the values as bars in TChart

Re: How can I read a *.txt file from disk and display the values as bars in TChart

Re: How can I read a *.txt file from disk and display the values as bars in TChart

Re: How can I read a *.txt file from disk and display the values as bars in TChart

Re: How can I read a *.txt file from disk and display the values as bars in TChart

Re: How can I read a *.txt file from disk and display the values as bars in TChart

Re: How can I read a *.txt file from disk and display the values as bars in TChart

Next basic question

Re: How can I read a *.txt file from disk and display the values as bars in TChart