File Formats (IFrIT)

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Current version

3.2.8
2009-08-22

File Formats

IFrIT understands the following file formats.

Regular mesh file: uniformly spaced 3-dimensional mesh of data values.
- Plain ASCII file. This file should have an extension "txt" (as in "myfile.txt", lower-case or upper-case does not matter) and should contain in its first line three integer numbers: the sizes of the mesh in X, Y, and Z directions. These dimensions do not have to be the same. Each line after the first one should contain one to three floating point numbers as values for the physical variables at each cell of the mesh. The first dimension changes the fastest. For example, the following file:
  12 33 55 1.0456 4.56768 2.45e-30 0.9866 5.45890 3.07e-20 ... (12*33*55+1 lines altogether)
  defines a 12 by 33 by 55 data mesh with all three physical variables defined. If only one or two floating point numbers are supplied in lines 2 to the last, the rest of physical variable remains undefined. The following FORTRAN code will create such a file from three arrays var1(n1,n2,n3), var2(n1,n2,n3), and var3(n1,n2,n3):
  An equivalent C code:
  An equivalent IDL code:
- Binary file. This file should have an extension "bin" (as in "myfile.bin") and should be a FORTRAN unformatted binary file. The following FORTRAN code will create such a file from three arrays var1(n1,n2,n3), var2(n1,n2,n3), and var3(n1,n2,n3):
  An equivalent C code (n1, n2, n3, and ntemp must be declared as long on a 16-bit machine and as int on a 32-bit or a 64-bit machine):
  (notice that the first and the last dimensions of the arrays are swapped - FORTRAN and C keep arrays in different order).
  An equivalent IDL code:
  Statement(s) shown in red statement may be omitted if the second and/or third variable are not loaded.
Particle file: three positions and optional three attributes for a set of particles.
- Plain ASCII file. This file should have an extension "txt" (as in "myfile.txt", lower-case or upper-case does not matter) and should contain in its first line one integer number: the total number of particles in the file. The second line should contain 6 numbers that determine how the particle positions relate to the bounding box. The first three numbers are X, Y, and Z coordinates of the lower-left-front corner of the bounding box in the units in which particle coordinates are given. The last three numbers are X, Y, and Z coordinates of the upper-right-back corner. For example, if you ran a simulation with a cubic box of 5 meters in size, and your particle positions are given in meters, and the left-lower-front corner of your box has coordinates of (0,0,0) meters, then the second line should be:
  Each line after the second one should contain three floating point numbers as values for the three coordinates for each particle and, optionally, up to three more numbers as values of attributes. The attributes can be used to distinguish particles in a set. For example, the following file:
  120 0.0 0.0 0.0 5.0 5.0 5.0 1.0456 4.56768 3.05678 2.45e-30 1.11e+10 0.555 0.9866 5.45890 -2.0568 3.07e-20 2.44e+11 -0.34 ... (120+2 lines altogether)
  defines a set of 120 particles with the single attribute field defined. Notice that the second particle is located outside the bounding box - there is nothing wrong with that. The following FORTRAN code will create such a file from six arrays x(n), y(n), z(n), attr1(n), attr2(n), attr3(n), where particles are located in a cubic box with the side of 5.0:
  An equivalent C code:
  An equivalent IDL code:
- Binary file. This file should have an extension "bin" (as in "myfile.bin") and should be a FORTRAN unformatted binary file. The following FORTRAN code will create such a file from six arrays x(n), y(n), z(n), attr1(n), attr2(n), attr3(n), where particles are located in a cubic box with the side of BoxLength:
  An equivalent C code (n and ntemp must be declared as long on a 16-bit machine and as int on a 32-bit or a 64-bit machine, temp as float):
  An equivalent IDL code:
  Statements shown in red statement may be omitted if the attributes are not needed.

Note #1: Reading binary file is much faster than reading an ASCII file.

Note #2: For the data file to be read correctly, the endiness of the data (big endian vs little endian) should be set via Options menu.

Note #3: All three physical variables from a mesh file must be positive - they are always stretched logarithmically when visualized. Particles attributes, however, can be both positive or negative, and can be interactively stretched linearly or logarithmically (there is a button to switch between the two modes).