Description Usage Arguments Details Value References Examples
Crop the curve set to the interval of distances [r_min, r_max], calculate residuals, scale the residuals and perform a deviation test with a chosen deviation measure.
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curve_set |
A curve_set or an |
r_min |
The minimum radius to include. |
r_max |
The maximum radius to include. |
use_theo |
Whether to use the theoretical summary function or the mean of the simulations. |
scaling |
The name of the scaling to use. Options include 'none', 'q', 'qdir' and 'st'. 'qdir' is default. |
measure |
The deviation measure to use. Default is 'max'. Must be one of the following: 'max', 'int', 'int2'. |
savedevs |
Logical. Should the global rank values k_i, i=1,...,nsim+1 be returned? Default: FALSE. |
... |
Arguments to be passed to the measure function, if applicable. |
The deviation test is based on a test function T(r) and it works as follows:
1) The test function estimated for the data, T_1(r), and for nsim simulations from the null model, T_2(r), ...., T_nsim+1(r), must be saved in 'curve_set' and given to the deviation_test function.
2) The deviation_test function then
Crops the functions to the chosen range of distances [r_min, r_max].
If the curve_set does not consist of residuals, i.e. curve_set$is_residual is FALSE (or does not exists), then the residuals d_i(r) = T_i(r) - T_0(r) are calculated, where T_0(r) is the expectation of T(r) under the null hypothesis. If use_theo = TRUE, the theoretical value given in the curve_set$theo is used for as T_0(r), if it is given. Otherwise, T_0(r) is estimated by the mean of T_j(r), j=2,...,nsim+1.
Scales the residuals. Options are
'none' No scaling. Nothing done.
'q' Quantile scaling.
'qdir' Directional quantile scaling.
'st' Studentised scaling.
See for details Myllymäki et al. (2013).
Calculates the global deviation measure u_i, i=1,...,nsim+1, see options for 'measure'.
'max' is the maximum deviation measure
u_i = max_(r in [r_min, r_max]) | w(r)(T_i(r) - T_0(r)) |
'int2'is the integral deviation measure
u_i = int_([r_min, r_max]) ( w(r)(T_i(r) - T_0(r)) )^2 dr
'int' is the 'absolute' integral deviation measure
u_i = int_([r_min, r_max]) | w(r)(T_i(r) - T_0(r)) | dr
Calculates the p-value.
Currently, there is no special way to take care of the same values of T_i(r) occuring possibly for small distances. Thus, it is preferable to exclude from the test the very small distances r for which ties occur.
If 'savedevs=FALSE' (default), the p-value is returned. If 'savedevs=TRUE', then a list containing the p-value and calculated deviation measures u_i, i=1,...,nsim+1 (where u_1 corresponds to the data pattern) is returned.
Myllymäki, M., Grabarnik, P., Seijo, H. and Stoyan. D. (2013). Deviation test construction and power comparison for marked spatial point patterns. arXiv:1306.1028
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 | ## Testing complete spatial randomness (CSR)
#-------------------------------------------
require(spatstat)
pp <- unmark(spruces)
# Generate nsim simulations under CSR, calculate L-function for the data and simulations
env <- envelope(pp, fun="Lest", nsim=999, savefuns=TRUE, correction="translate")
# The deviation test using the integral deviation measure
res <- deviation_test(env, measure = 'int')
res
# or
res <- deviation_test(env, r_min=0, r_max=7, measure='int2')
## Random labeling test
#----------------------
mpp <- spruces
# T(r) = \hat{L}_m(r), an estimator of the L_m(r) function
curve_set <- random_labelling(mpp, mtf_name = 'm', nsim=999, r_min=1.5, r_max=9.5)
res <- deviation_test(curve_set, measure='int2')
res
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