.. _generate_bins:

*******************************************
Specifying the separation bins in Corrfunc
*******************************************

All of the python extensions for `Corrfunc` accept
either a filename or an array for specifying the
:math:`r_p` or :math:`\theta`. 

Manually creating a file with arbitrary bins
--------------------------------------------
This manual method lets you specify generic bins 
as long as the upper-edge of one bin is the 
same as the lower-edge of the next (i.e., continuous bins). The
bins themselves can have arbitrary widths, and the
smallest bin can start from 0.0. 

* Open a text editor with a new file
* Add two columns per bin you want, the first
  column should be low-edge of the bin while
  the second column should be the high-edge
  of the bin. Like so:

::
   
    0.10     0.15

* Now add as many such lines as the number of bins you
  want. Here is a valid example:

::
  
     0.10     0.15
     0.15     0.50
     0.50     5.00

This example specifies 3 bins, with the individual
bin limits specified on each line. Notice that the
width of each bin can be independently specified (but
the bins **do** have to be continuous)
  
.. note:: Make sure that the bins are in increasing order -- smallest bin first, then the next smallest
          bin and so on up to the largest bin.
          
Specifying bins as an array
---------------------------

You can specify the bins using ``numpy.linspace`` or
``numpy.logspace``. 

.. code:: python

          import numpy as np
          rmin = 0.1
          rmax = 10.0
          nbins = 20
          rbins = np.linspace(rmin, rmax, nbins + 1)
          log_rbins = np.logspace(np.log10(rmin), np.log10(rmax), nbins + 1)