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] 692 910 69 794 546 381 490 507 682 711 ...
wand.nn[[1]][1:20, 1:10]
##       [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
##  [1,]  692  180  134  605  990  997  878  865  628   741
##  [2,]  910  532  513   22  594  584  757  902  696   446
##  [3,]   69    7  668  525  579  207  458  245  587   806
##  [4,]  794  462  390   30  905   51  399  864  700   391
##  [5,]  546  776  396  503  125   94   78  863  678   200
##  [6,]  381  690  129  985  470  807  556  693  391   208
##  [7,]  490  519  348  587  882  758  926  954    3   668
##  [8,]  507  668   89  909  376   83  207  724  704   806
##  [9,]  682  341  206  396  768  990  899  505  634   645
## [10,]  711  426  869  416  473  733  181  176  368   725
## [11,]  312  836  921  817  877  270  814  651  684    29
## [12,]  146  744  810  658  482   81  140  163  933   476
## [13,]  564  156  552  893  891  844  810  578  163   457
## [14,]  742  631  464  168  768  206  486  545  338   178
## [15,]  922  500  284  702  544  109  217  574  870   249
## [16,]  631   32  355  693  257  438  924  692  635   869
## [17,]  851  553  825  943  783  836  310  959  270   740
## [18,]  296  636  763  444  512  723  569  480  786   553
## [19,]  847  463  659  579   69  232  144    3    7   133
## [20,]  817  967  669  944  785  713  440  714  128   907
# Distance
str(wand.nn[[2]])
##  num [1:1000, 1:30] 3.32 4.07 3.47 3.34 2.38 ...
wand.nn[[2]][1:20, 1:10]
##           [,1]     [,2]     [,3]     [,4]     [,5]     [,6]     [,7]     [,8]
##  [1,] 3.324007 3.511635 3.575698 3.579314 3.680856 3.722603 3.723496 3.759774
##  [2,] 4.067747 4.321824 4.354522 4.529473 4.858189 4.917033 4.946630 4.963609
##  [3,] 3.471128 3.929520 3.950912 3.962134 4.009265 4.033075 4.040213 4.231706
##  [4,] 3.339712 3.536500 3.569078 3.640033 3.666499 3.704852 3.721144 3.805600
##  [5,] 2.379315 2.923955 3.011268 3.035327 3.081000 3.088763 3.129264 3.216845
##  [6,] 3.117810 3.287697 3.320573 3.380606 3.447816 3.481008 3.486953 3.642018
##  [7,] 3.072292 3.489735 3.514234 3.582117 3.685677 3.748258 3.824062 3.850488
##  [8,] 3.581189 3.627823 3.668141 3.703606 3.901613 3.902774 4.110172 4.131634
##  [9,] 3.495569 3.818980 3.842952 4.016127 4.070209 4.189340 4.289584 4.296608
## [10,] 3.037817 3.761022 3.898579 4.098345 4.142594 4.156749 4.223230 4.265053
## [11,] 2.210230 2.288887 2.772077 2.781540 2.869389 2.874490 2.890439 2.950053
## [12,] 3.273305 3.496418 3.499258 3.543294 3.549349 3.563866 3.672853 3.745756
## [13,] 2.958366 3.310175 3.644414 3.683244 3.695702 3.716734 3.721237 3.754304
## [14,] 4.141562 4.148297 4.247029 4.338482 4.351993 4.385360 4.422976 4.424390
## [15,] 3.482856 3.756475 3.768423 3.830020 4.092452 4.176408 4.425750 4.528185
## [16,] 3.371937 3.375490 3.378451 3.417463 3.443673 3.469108 3.474380 3.477685
## [17,] 3.136938 3.278147 3.339877 3.884283 3.886972 3.890158 3.896328 3.935037
## [18,] 2.539880 2.750091 2.931691 2.969394 3.014138 3.188564 3.204252 3.358280
## [19,] 3.796821 3.884775 4.429177 4.512180 4.664446 4.830093 4.835052 4.839944
## [20,] 3.349702 3.456222 3.595167 3.799887 3.833191 3.874075 3.877324 3.882934
##           [,9]    [,10]
##  [1,] 3.760152 3.778633
##  [2,] 4.971256 4.976674
##  [3,] 4.243348 4.294548
##  [4,] 3.846483 3.870368
##  [5,] 3.232554 3.265382
##  [6,] 3.647594 3.656394
##  [7,] 3.929520 3.984988
##  [8,] 4.146137 4.301980
##  [9,] 4.336782 4.363452
## [10,] 4.284476 4.290094
## [11,] 3.002259 3.006277
## [12,] 3.810625 3.870339
## [13,] 3.755291 3.813738
## [14,] 4.458244 4.497944
## [15,] 4.820698 4.822509
## [16,] 3.539122 3.553833
## [17,] 3.974056 4.001891
## [18,] 3.393188 3.467801
## [19,] 4.848027 4.881011
## [20,] 3.892192 3.893678

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                       0.927                      0.905                  0.979
##  2                       0.766                      0.943                  0.996
##  3                       0.792                      0.791                  0.996
##  4                       1                          0.766                  0.996
##  5                       1                          0.481                  0.979
##  6                       0.499                      0.616                  0.996
##  7                       0.887                      0.826                  0.994
##  8                       0.932                      0.508                  1    
##  9                       1                          0.901                  0.979
## 10                       0.919                      0.486                  0.996
## # 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        -0.110        -0.00933         1.03                    -0.0130
##  2        -0.267        -0.158           0.863                   -0.698 
##  3         0.431        -0.0942         -0.148                   -1.56  
##  4        -0.0949        0.966           0.577                   -1.15  
##  5        -0.249        -0.258          -0.0365                  -0.467 
##  6        -0.110         0.373           0.316                    0.891 
##  7        -0.249        -0.105           0.988                   -0.718 
##  8         0.902         0.203           1.80                     0.597 
##  9         0.254         0.371           0.0930                  -0.145 
## 10        -0.439        -0.826          -0.997                   -0.814 
## # 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] 0.257 0.199 0.226 0.253 0.303 ...