.. _converting_rp_pi_counts:

Converting :math:`(r_p, \pi)` pairs into a projected correlation function
==========================================================================

Pair counts in :math:`(r_p, \pi)` can be converted into a projected correlation function
by using the helper function :py:mod:`Corrfunc.utils.convert_rp_pi_counts_to_wp`.

.. code-block:: python

          >>> import numpy as np
          >>> from Corrfunc.theory import DDrppi
          >>> from Corrfunc.io import read_catalog
          >>> from Corrfunc.utils import convert_rp_pi_counts_to_wp
          
          # Read the supplied galaxies on a periodic box          
          >>> X, Y, Z = read_catalog()
          >>> N = len(X)
          >>> boxsize = 420.0

          # Generate randoms on the box          
          >>> rand_N = 3*N
          >>> rand_X = np.random.uniform(0, boxsize, rand_N)
          >>> rand_Y = np.random.uniform(0, boxsize, rand_N)
          >>> rand_Z = np.random.uniform(0, boxsize, rand_N)
          >>> nthreads = 2
          >>> pimax = 40.0

          # Setup the bins
          >>> nrpbins = 10
          >>> bins = np.linspace(0.1, 10.0, nrpbins + 1)

          # Auto pair counts in DD          
          >>> autocorr=1
          >>> DD_counts = DDrppi(autocorr, nthreads, pimax, bins, X, Y, Z,
          ...                   periodic=False, verbose=True)

          # Cross pair counts in DR          
          >>> autocorr=0                   
          >>> DR_counts = DDrppi(autocorr, nthreads, pimax, bins, X, Y, Z,
          ...                   X2=rand_X, Y2=rand_Y, Z2=rand_Z,
          ...                   periodic=False, verbose=True)

          # Auto pairs counts in RR          
          >>> autocorr=1
          >>> RR_counts = DDrppi(autocorr, nthreads, pimax, bins, rand_X, rand_Y, rand_Z,
          ...                   periodic=False, verbose=True)

          # All the pair counts are done, get the correlation function          
          >>> wp = convert_rp_pi_counts_to_wp(N, N, rand_N, rand_N,
          ...                                 DD_counts, DR_counts,
          ...                                 DR_counts, RR_counts, nrpbins, pimax)

See the complete reference here :py:mod:`Corrfunc`.