# Comprehensive Halotools Reference/API¶

## halotools.empirical_models Package¶

### Classes¶

 FoFGroups(positions, b_perp, b_para[, …]) Friends-of-friends (FoF) groups class.

## halotools.mock_observables.pair_counters Package¶

### Functions¶

 marked_npairs_3d(sample1, sample2, rbins[, …]) Calculate the number of weighted pairs with separations greater than or equal to r, $$W(>r)$$. marked_npairs_xy_z(sample1, sample2, …[, …]) Calculate the number of weighted pairs with separations greater than or equal to $$r_{\perp}$$ and $$r_{\parallel}$$, $$W(>r_{\perp},>r_{\parallel})$$. npairs_3d(sample1, sample2, rbins[, period, …]) Function counts the number of pairs of points separated by a three-dimensional distance smaller than the input rbins. npairs_jackknife_3d(sample1, sample2, rbins) Pair counter used to make jackknife error estimates of real-space pair counter npairs. npairs_jackknife_xy_z(sample1, sample2, …) Pair counter used to make jackknife error estimates of redshift-space pair counter npairs_xy_z. npairs_per_object_3d(sample1, sample2, rbins) Function counts the number of points in sample2 separated by a distance r from each point in sample1, where r is defined by the input rbins. npairs_projected(sample1, sample2, rp_bins, …) Function counts the number of pairs of points with separation in the xy-plane less than the input rp_bins and separation in the z-dimension less than the input pi_max. npairs_s_mu(sample1, sample2, s_bins, mu_bins) Function counts the number of pairs of points separated by less than radial separation, $$s$$, given by s_bins and angular distance, $$\mu\equiv\cos(\theta_{\rm los})$$, given by mu_bins, where $$\theta_{\rm los}$$ is the angle between $$\vec{s}$$ and the line-of-sight (LOS). npairs_xy_z(sample1, sample2, rp_bins, pi_bins) Function counts the number of pairs of points with separation in the xy-plane less than the input rp_bins and separation in the z-dimension less than the input pi_bins. pairwise_distance_3d(data1, data2, r_max[, …]) Function returns pairs of points separated by a three-dimensional distance smaller than or eqaul to the input r_max. pairwise_distance_xy_z(data1, data2, rp_max, …) Function returns pairs of points separated by a xy-projected distance smaller than or eqaul to the input rp_max and z distance pi_max. weighted_npairs_s_mu(sample1, sample2, …) Function performs a weighted count of the number of pairs of points separated by less than radial separation, $$s$$, given by s_bins and angular distance, $$\mu\equiv\cos(\theta_{\rm los})$$, given by mu_bins, where $$\theta_{\rm los}$$ is the angle between $$\vec{s}$$ and the line-of-sight (LOS).

### Classes¶

 RectangularDoubleMesh(x1, y1, z1, x2, y2, …) Fundamental data structure of the mock_observables sub-package. RectangularDoubleMesh2D(x1, y1, x2, y2, …) Fundamental data structure of the mock_observables sub-package.

## halotools.mock_observables.pair_counters.marked_cpairs Package¶

### Functions¶

 conditional_pairwise_distance_no_pbc Calculate the conditional limited pairwise distance matrix, $$d_{ij}$$. conditional_pairwise_xy_z_distance_no_pbc Calculate the conditional limited pairwise distance matrices, $$d_{{\perp}ij}$$ and $$d_{{\parallel}ij}$$. marked_npairs_3d_engine Cython engine for counting pairs of points as a function of three-dimensional separation. marked_npairs_xy_z_engine Cython engine for counting pairs of points as a function of three-dimensional separation.