Statistics¶

Collection of tools for calculating statistics.

CDF¶

Cumulative Distribution Function¶

pygeostat.statistics.cdf.cdf(var, weights=None, lower=None, upper=None, bins=None)¶

Calculates an empirical CDF using the standard method of the midpoint of a histogram bin. Assumes that the data is already trimmed or that iwt=0 for variables which are not valid.

If ‘bins’ are provided, then a binned histogram approach is used. Otherwise, the CDF is constructed using all points (as done in GSLIB).

Notes: ‘lower’ and ‘upper’ limits for the CDF may be supplied and will be returned appropriately

Parameters

var (array) – Array passed to the cdf function
weights (str) – column where the weights are stored
Lower (float) – Lower limit
upper (float) – Upper Limit
bins (int) – Number of bins to use

Returns

np.ndarray: array of bin midpoints
cdf: np.ndarray: cdf values for each midpoint value

Return type

midpoints

Percentile from CDF¶

pygeostat.statistics.cdf.percentile_from_cdf(cdf_x, cdf, percentile)¶: Given ‘x’ values of a CDF and corresponding CDF values, find a given percentile. Percentile may be a single value or an array-like and must be in [0, 100] or CDF bounds

z_percentile¶

pygeostat.statistics.cdf.z_percentile(z, cdf_x, cdf)¶: Given ‘cdf_x` values of a CDF and corresponding cdf values, find the percetile of a given value z. Percentile may be a single value or an array-like and must be in [0, 100] or CDF bounds.

Build Indicator CDF¶

pygeostat.statistics.cdf.build_indicator_cdf(prob_ik, zvals)¶

Build the X-Y data required to plot a categorical cdf

Parameters

prob_ik – np.ndarray the p-vals corresponding to the cutoffs
zvals – np.ndarray the corresponding z-value specifying the cutoffs

Returns

np.ndarray: the x and y coordinates of (1) the cutoffs and (2) the midpoints for each cutoff

Return type

points, midpoints

Variance From CDF¶

pygeostat.statistics.cdf.variance_from_cdf(cdfx, cdfy, nsample=1000)¶: Compute the variance by randomly sampling the cdf by brute force

Stdev From CDF¶

pygeostat.statistics.cdf.stdev_from_cdf(cdfx, cdfy, nsample=1000)¶: Compute the stdsev of the cdf from a n-sample sized random sample from the cdf

Kernel Density Estimation Functions¶

Univariate KDE with StatsModels¶

pygeostat.statistics.kde.kde_statsmodels_u(x, x_grid, bandwidth=0.2, **kwargs)¶: Univariate Kernel Density Estimation with Statsmodels

Multivariate KDE with StatsModels¶

pygeostat.statistics.kde.kde_statsmodels_m(x, x_grid, bandwidth=0.2, **kwargs)¶: Multivariate Kernel Density Estimation with Statsmodels

KDE with Scikit-learn¶

pygeostat.statistics.kde.kde_sklearn(x, x_grid, bandwidth=0.2, **kwargs)¶: Kernel Density Estimation with Scikit-learn

KDE with Scipy¶

pygeostat.statistics.kde.kde_scipy(x, x_grid, bandwidth=0.2, **kwargs)¶: Kernel Density Estimation based on different packages and different kernels Note that scipy weights its bandwidth by the covariance of the input data. To make the results comparable to the other methods, we divide the bandwidth by the sample standard deviation here.

Weighted Statistics¶

Weighted Mean¶

pygeostat.statistics.utils.weighted_mean(var, wts)¶: Calculates the weighted mean

Weighted Variance¶

pygeostat.statistics.utils.weighted_variance(var, wts)¶: Calculates the weighted variance

Weighted Skewness¶

pygeostat.statistics.utils.weighted_skew(var, wts)¶: Calculates the weighted skewness

Weighted Kurtosis¶

pygeostat.statistics.utils.weighted_kurtosis(var, wts)¶: Calculates the weighted skewness

Weighted Correlation¶

pygeostat.statistics.utils.weighted_correlation(x, y, wt)¶: Calculates the weighted correlation

Weighted Rank Correlation¶

pygeostat.statistics.utils.weighted_correlation_rank(x, y, wt)¶: Calculatees the weighted spearman rank correlation

Weighted Covariance¶

pygeostat.statistics.utils.weighted_covariance(x, y, wt)¶: Calculates the weighted covariance

Assorted Stats Functions¶

Nearest Positive Definite Correlation Matrix¶

pygeostat.statistics.utils.near_positive_definite(input_matrix)¶

This function uses R to calculate the nearest positive definite matrix within python. An installation of R with the library “Matrix” is required. The module rpy2 is also needed

The only requirement is an input matrix. Can be either a pandas dataframe or numpy-array.

Parameters: input_matrix – input numpy array or pandas dataframe, not numpy matrix
Returns: Nearest positive definite matrix as a numpy-array
Return type: (np.array)

Accuracy Plot Statistics - Simulation¶

pygeostat.statistics.utils.accsim(truth, reals, pinc=0.05)¶

Calculates the proportion of locations where the true value falls within symmetric p-PI intervals when completing a jackknife study. A portion of the data is excluded from the conditioning dataset and the excluded sample locations simulated values are then checked.

Accuracy Plot Statistics - CDF thresholds¶

pygeostat.statistics.utils.accmik(truth, thresholds, mikprobs, pinc=0.05)¶

Similar to accsim but accepting mik distributions instead

Mostly pulled from accsim

Parameters

truth (np.ndarray) – Tidy (long-form) 1D data where a single column containing the true values. A pandas dataframe/series or numpy array can be passed
thresholds (np.ndarray) – 1D array of thresholds where each CDF is defined by these thresholds and the probability given in the mikprobs array for each location.
mikprobs (np.ndarray) – Tidy (long-form) 2D data where a single column contains values from a single MIK cutoff and each row contains the simulated values for the corresponding single truth location. A pandas dataframe or numpy matrix can be passed
pinc (float) – Increments between the probability intervals to calculate within (0, 1)

Returns

propavg (pd.DataFrame) – Dataframe with the calculated probability intervals and the fraction within the interval
sumstats (dict) – Dictionary containing the average variance (U), mean squared error (MSE), accuracy measure (acc), precision measure (pre), and a goodness measure (goo)

PostSim¶

pygeostat.statistics.postsim.postsim_multfiles(file_base_or_list, output_name, Nr=None, file_ending=None, fltype=None, output_fltype=None, zero_padding=0, variables=None, var_min=None)¶

The multiple file postsim function uses recursive statistics for memory management and coolness factor. See http://people.revoledu.com/kardi/tutorial/RecursiveStatistic/ This function will take multiple realizations and post process the results into mean and variance for each variable. You can either pass it a list of files to iterate through or a filebase name and the number of realizations.

Parameters

file_base_or_list (list) or (str) – List of files or path + base name of sequentially named files
output_name (str) – ath (or name) of file to write output to.
Nr (int) – Number of realizations. Needed if file base name is passed.
file_ending (str) – file ending (ex. “out”). Used if file base name is passed. Period is not included.
fltype (str) – Type of data file: either csv, gslib, hdf5, or gsb. Used if file base name is passed and file_ending is not used.
output_fltype (str) – Type of output data file: either csv, gslib, hdf5, or gsb.
zero_padding (int) – Number of zeros to padd number in sequentially named files with. Default is 0.
variables (str) – List of variables to process.
var_min (list) or (float) – Minimum trimming limit to use. If one value is passed it will apply the trimming limit to all variables. Or a list of trimming limit for each variable can be passed.