K-nearest neighbors:

We read in input.scone.csv, which is our file modified (and renamed) from the get.marker.names() function. The K-nearest neighbor generation is derived from the Fast Nearest Neighbors (FNN) R package, within our function Fnn(), which takes as input the “input markers” to be used, along with the concatenated data previously generated, and the desired k. We advise the default selection to the total number of cells in the dataset divided by 100, as has been optimized on existing mass cytometry datasets. The output of this function is a matrix of each cell and the identity of its k-nearest neighbors, in terms of its row number in the dataset used here as input.

library(Sconify)
# Markers from the user-generated excel file
marker.file <- system.file('extdata', 'markers.csv', package = "Sconify")
markers <- ParseMarkers(marker.file)

# How to convert your excel sheet into vector of static and functional markers
markers
## $input
##  [1] "CD3(Cd110)Di"           "CD3(Cd111)Di"           "CD3(Cd112)Di"          
##  [4] "CD235-61-7-15(In113)Di" "CD3(Cd114)Di"           "CD45(In115)Di"         
##  [7] "CD19(Nd142)Di"          "CD22(Nd143)Di"          "IgD(Nd145)Di"          
## [10] "CD79b(Nd146)Di"         "CD20(Sm147)Di"          "CD34(Nd148)Di"         
## [13] "CD179a(Sm149)Di"        "CD72(Eu151)Di"          "IgM(Eu153)Di"          
## [16] "Kappa(Sm154)Di"         "CD10(Gd156)Di"          "Lambda(Gd157)Di"       
## [19] "CD24(Dy161)Di"          "TdT(Dy163)Di"           "Rag1(Dy164)Di"         
## [22] "PreBCR(Ho165)Di"        "CD43(Er167)Di"          "CD38(Er168)Di"         
## [25] "CD40(Er170)Di"          "CD33(Yb173)Di"          "HLA-DR(Yb174)Di"       
## 
## $functional
##  [1] "pCrkL(Lu175)Di"  "pCREB(Yb176)Di"  "pBTK(Yb171)Di"   "pS6(Yb172)Di"   
##  [5] "cPARP(La139)Di"  "pPLCg2(Pr141)Di" "pSrc(Nd144)Di"   "Ki67(Sm152)Di"  
##  [9] "pErk12(Gd155)Di" "pSTAT3(Gd158)Di" "pAKT(Tb159)Di"   "pBLNK(Gd160)Di" 
## [13] "pP38(Tm169)Di"   "pSTAT5(Nd150)Di" "pSyk(Dy162)Di"   "tIkBa(Er166)Di"
# Get the particular markers to be used as knn and knn statistics input
input.markers <- markers[[1]]
funct.markers <- markers[[2]]

# Selection of the k. See "Finding Ideal K" vignette
k <- 30

# The built-in scone functions
wand.nn <- Fnn(cell.df = wand.combined, input.markers = input.markers, k = k)
# Cell identity is in rows, k-nearest neighbors are columns
# List of 2 includes the cell identity of each nn, 
#   and the euclidean distance between
#   itself and the cell of interest

# Indices
str(wand.nn[[1]])
##  int [1:1000, 1:30] 882 113 526 832 795 761 541 999 551 61 ...
wand.nn[[1]][1:20, 1:10]
##       [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
##  [1,]  882  725  534  429  474  140  903  640   64   334
##  [2,]  113  387  364  208  909   82  228  865  763   255
##  [3,]  526  947  498  250  976   60   53  809  658   179
##  [4,]  832  547  739   42  519  500  234   48  334   186
##  [5,]  795  832  750  500   42  668  501  336  588   617
##  [6,]  761  965   80  447  495  796  256  492  507   286
##  [7,]  541  503   20  169  499  579  206  275  303   344
##  [8,]  999  199  153  604  800  464  453  112  794    56
##  [9,]  551  257  886  230  151  433  706  885  120    58
## [10,]   61  180  505   78  441  661  723  979  895   919
## [11,]  270  848  503  877  912  813   20  206   35    23
## [12,]  373  502  922    3  906  498  930  333  698   745
## [13,]  261  501  619  305  207  588  191   25  649   832
## [14,]  778  385  477  279   31   29  711  425  705   432
## [15,]  272  376  562  535  969  426  262  569  666   308
## [16,]  788  112  604  256  424  969  684  569  392   453
## [17,]  539  643  112  688  535  405  281  681   16   604
## [18,]  666  199  774  424  569  840  627  353  826   492
## [19,]  395  207  584  672  906  807   96  384   67   492
## [20,]  683  579  819  344  503  541  221    7  128   772
# Distance
str(wand.nn[[2]])
##  num [1:1000, 1:30] 3.94 3.06 3.2 3.34 2.94 ...
wand.nn[[2]][1:20, 1:10]
##           [,1]     [,2]     [,3]     [,4]     [,5]     [,6]     [,7]     [,8]
##  [1,] 3.936057 4.818958 4.938966 4.975562 5.020366 5.021473 5.044814 5.053021
##  [2,] 3.061246 3.307469 3.331167 3.470828 3.643701 3.687836 3.698633 3.698943
##  [3,] 3.195276 3.301789 3.310175 3.357944 3.407100 3.483313 3.538887 3.591911
##  [4,] 3.341014 3.439879 3.578891 3.615235 3.721213 3.757769 3.770940 3.786052
##  [5,] 2.936505 2.942758 3.147516 3.175475 3.425969 3.468957 3.499053 3.623105
##  [6,] 3.804883 3.975199 4.641285 4.665559 4.701645 4.711032 4.846632 5.023005
##  [7,] 2.642065 2.768876 3.006399 3.030025 3.105921 3.199420 3.275014 3.338633
##  [8,] 3.319466 3.540251 3.544454 3.545528 3.644055 3.655483 3.705929 3.723749
##  [9,] 3.958606 3.980797 4.217798 4.330786 4.337176 4.399225 4.467726 4.482436
## [10,] 3.645440 4.392323 4.445316 4.471956 4.500594 4.610302 4.611345 4.724322
## [11,] 2.995699 3.143790 3.172041 3.268888 3.321594 3.337925 3.365813 3.380381
## [12,] 3.425248 3.431334 3.641398 3.866902 3.906731 3.961563 4.106953 4.145391
## [13,] 2.881072 3.015790 3.063677 3.068584 3.090575 3.091802 3.118784 3.167195
## [14,] 3.181706 3.356851 3.359119 3.657086 3.786363 3.844428 3.876545 3.985128
## [15,] 3.874802 3.931893 4.046980 4.175979 4.228581 4.305845 4.344556 4.348705
## [16,] 2.736076 2.932863 2.975477 3.000608 3.003486 3.008601 3.044186 3.099771
## [17,] 3.616236 3.887278 3.935782 3.965962 4.088930 4.186605 4.213913 4.235365
## [18,] 2.860810 2.916131 2.936378 3.023871 3.113233 3.203687 3.210857 3.265621
## [19,] 3.259314 3.280480 3.288206 3.317002 3.474107 3.505896 3.543742 3.548727
## [20,] 1.991096 2.139081 2.141978 2.595782 2.867829 2.908637 2.978875 3.006399
##           [,9]    [,10]
##  [1,] 5.095593 5.164546
##  [2,] 3.743360 3.757137
##  [3,] 3.601772 3.634230
##  [4,] 3.953905 4.005098
##  [5,] 3.630752 3.667818
##  [6,] 5.060767 5.094215
##  [7,] 3.390195 3.394642
##  [8,] 3.728963 3.791444
##  [9,] 4.554737 4.582723
## [10,] 4.802364 4.835690
## [11,] 3.381674 3.403471
## [12,] 4.230430 4.248557
## [13,] 3.245717 3.246812
## [14,] 3.999606 4.020765
## [15,] 4.360477 4.381247
## [16,] 3.109655 3.120947
## [17,] 4.284406 4.304534
## [18,] 3.290374 3.350413
## [19,] 3.713421 3.723879
## [20,] 3.073372 3.074654

Finding scone values:

This function iterates through each KNN, and performs a series of calculations. The first is fold change values for each maker per KNN, where the user chooses whether this will be based on medians or means. The second is a statistical test, where the user chooses t test or Mann-Whitney U test. I prefer the latter, because it does not assume any properties of the distributions. Of note, the p values are adjusted for false discovery rate, and therefore are called q values in the output of this function. The user also inputs a threshold parameter (default 0.05), where the fold change values will only be shown if the corresponding statistical test returns a q value below said threshold. Finally, the “multiple.donor.compare” option, if set to TRUE will perform a t test based on the mean per-marker values of each donor. This is to allow the user to make comparisons across replicates or multiple donors if that is relevant to the user’s biological questions. This function returns a matrix of cells by computed values (change and statistical test results, labeled either marker.change or marker.qvalue). This matrix is intermediate, as it gets concatenated with the original input matrix in the post-processing step (see the relevant vignette). We show the code and the output below. See the post-processing vignette, where we show how this gets combined with the input data, and additional analysis is performed.

wand.scone <- SconeValues(nn.matrix = wand.nn, 
                      cell.data = wand.combined, 
                      scone.markers = funct.markers, 
                      unstim = "basal")

wand.scone
## # A tibble: 1,000 × 34
##    `pCrkL(Lu175)Di.IL7.qvalue` pCREB(Yb176)Di.IL7.qvalu…¹ pBTK(Yb171)Di.IL7.qv…²
##                          <dbl>                      <dbl>                  <dbl>
##  1                       0.939                      0.994                  0.931
##  2                       0.971                      0.951                  0.941
##  3                       0.964                      0.994                  0.980
##  4                       0.998                      0.951                  0.931
##  5                       0.939                      0.994                  0.921
##  6                       0.971                      0.994                  1    
##  7                       0.998                      1                      1    
##  8                       0.909                      0.951                  0.956
##  9                       0.971                      0.994                  0.947
## 10                       0.971                      0.994                  0.975
## # ℹ 990 more rows
## # ℹ abbreviated names: ¹​`pCREB(Yb176)Di.IL7.qvalue`,
## #   ²​`pBTK(Yb171)Di.IL7.qvalue`
## # ℹ 31 more variables: `pS6(Yb172)Di.IL7.qvalue` <dbl>,
## #   `cPARP(La139)Di.IL7.qvalue` <dbl>, `pPLCg2(Pr141)Di.IL7.qvalue` <dbl>,
## #   `pSrc(Nd144)Di.IL7.qvalue` <dbl>, `Ki67(Sm152)Di.IL7.qvalue` <dbl>,
## #   `pErk12(Gd155)Di.IL7.qvalue` <dbl>, `pSTAT3(Gd158)Di.IL7.qvalue` <dbl>, …

For programmers: performing additional per-KNN statistics

If one wants to export KNN data to perform other statistics not available in this package, then I provide a function that produces a list of each cell identity in the original input data matrix, and a matrix of all cells x features of its KNN.

I also provide a function to find the KNN density estimation independently of the rest of the “scone.values” analysis, to save time if density is all the user wants. With this density estimation, one can perform interesting analysis, ranging from understanding phenotypic density changes along a developmental progression (see post-processing vignette for an example), to trying out density-based binning methods (eg. X-shift). Of note, this density is specifically one divided by the aveage distance to k-nearest neighbors. This specific measure is related to the Shannon Entropy estimate of that point on the manifold (https://hal.archives-ouvertes.fr/hal-01068081/document).

I use this metric to avoid the unusual properties of the volume of a sphere as it increases in dimensions (https://en.wikipedia.org/wiki/Volume_of_an_n-ball). This being said, one can modify this vector to be such a density estimation (example http://www.cs.haifa.ac.il/~rita/ml_course/lectures_old/KNN.pdf), by treating the distance to knn as the radius of a n-dimensional sphere and incoroprating said volume accordingly.

An individual with basic programming skills can iterate through these elements to perform the statistics of one’s choosing. Examples would include per-KNN regression and classification, or feature imputation. The additional functionality is shown below, with the example knn.list in the package being the first ten instances:

# Constructs KNN list, computes KNN density estimation
wand.knn.list <- MakeKnnList(cell.data = wand.combined, nn.matrix = wand.nn)
wand.knn.list[[8]]
## # A tibble: 30 × 51
##    `CD3(Cd110)Di` `CD3(Cd111)Di` `CD3(Cd112)Di` `CD235-61-7-15(In113)Di`
##             <dbl>          <dbl>          <dbl>                    <dbl>
##  1        -0.0528        -0.313         -0.273                   -1.77  
##  2        -0.180         -0.255         -0.0147                  -0.455 
##  3        -0.0957        -0.176         -0.199                   -0.493 
##  4         0.787         -0.239          0.0882                   0.0555
##  5        -0.0728        -0.253         -0.426                   -0.429 
##  6        -0.597         -0.242         -0.106                   -0.624 
##  7        -0.148          0.816         -0.0442                  -1.36  
##  8        -0.0855        -0.406         -0.487                   -0.833 
##  9        -0.174         -0.613         -0.0850                  -0.783 
## 10        -0.125         -0.0787        -0.174                   -1.12  
## # ℹ 20 more rows
## # ℹ 47 more variables: `CD3(Cd114)Di` <dbl>, `CD45(In115)Di` <dbl>,
## #   `CD19(Nd142)Di` <dbl>, `CD22(Nd143)Di` <dbl>, `IgD(Nd145)Di` <dbl>,
## #   `CD79b(Nd146)Di` <dbl>, `CD20(Sm147)Di` <dbl>, `CD34(Nd148)Di` <dbl>,
## #   `CD179a(Sm149)Di` <dbl>, `CD72(Eu151)Di` <dbl>, `IgM(Eu153)Di` <dbl>,
## #   `Kappa(Sm154)Di` <dbl>, `CD10(Gd156)Di` <dbl>, `Lambda(Gd157)Di` <dbl>,
## #   `CD24(Dy161)Di` <dbl>, `TdT(Dy163)Di` <dbl>, `Rag1(Dy164)Di` <dbl>, …
# Finds the KNN density estimation for each cell, ordered by column, in the 
# original data matrix
wand.knn.density <- GetKnnDe(nn.matrix = wand.nn)
str(wand.knn.density)
##  num [1:1000] 0.191 0.258 0.265 0.25 0.271 ...