A for循环与rowSums功能

我是一个R的初学者，我已经写了一个双循环计算chi2值，用于选择6610个术语和10个类中的特征。这里是我的循环：A for循环与rowSums功能

library(raster) 
    #for x^2 [n,r] = term n, class r. n starts from col #7 and r starts from col #6617 

    chi2vals <- matrix(0:0,6610,10) 
    chi2avgs <- vector("numeric",6610L) 

    for(r in 1:10){ 
    for(n in 1:6610){ 

     A = sum(data1.sub.added[,6+n]==1 & data1.sub.added[,6616+r]==1) 
     M = sum(data1.sub.added[,6+n]==1) 
     P = sum(data1.sub.added[,6616+r]==1) 
     N = nrow(data1.sub.added) 
     E = ((A*N)-(M*P))**2 
     F = (N-P)*(N-M) 
     chi2vals[n,r] = (N/(P*M))*(E/F) # for term n 
    } 

    Prcj = sum(data1.sub.added[,6616+r]==1)/sum(data1.sub.added[,6616:6626]==1) #probability of class c_r 
    pchi <- Prcj * chi2vals 
    chi2avgs[n] = rowSums(pchi)[n] 
    }

代码正确地计算出一切直到行pchi <- Prcj * chi2vals。其结果是P *卡方值的一个很好的矩阵：

> head(pchi) 
      [,1]  [,2]   [,3]  [,4]  [,5]   [,6]  [,7]  [,8]   [,9] 
[1,] 128.36551442 0.239308113 0.683517530 1.5038665 0.6145058 3.656857e-01 1.3311564 2.6977448 0.410702803 
[2,] 0.06632758 0.067970859 0.019178551 0.2900692 1.5300639 4.430705e-08 0.2599859 0.6362953 0.098745147 
[3,] 1.85641330 1.411925435 3.590747764 7.3018416 38.8044465 4.102248e-01 6.4118078 13.0164994 1.709506238 
[4,] 0.11063892 0.005039029 0.244964758 0.1622654 0.1156411 8.274468e+00 0.2564959 0.0577651 0.242946022 
[5,] 0.04788648 0.049072885 0.001420669 0.2094211 1.7200152 2.045923e-01 0.1877019 0.1468187 0.005493183 
[6,] 5.39946188 6.899336618 60.735646913 7.4351538 10.7005784 9.946261e+00 35.8868899 178.7112406 11.382740754 
      [,10] 
[1,] 0.26436516 
[2,] 0.14414444 
[3,] 0.90292073 
[4,] 0.01168997 
[5,] 0.06641298 
[6,] 19.68599142

但最后chi2avgs值大多变成是零：

> head(chi2avgs) 
[1] 0.000000 0.000000 0.000000 0.000000 2.638835 0.000000

然而，从循环时，一边我与任何代替n号，最后一行效果很好：

chi2avgs[1] = rowSums(pchi)[1] 
    chi2avgs[2] = rowSums(pchi)[2] 
    chi2avgs[3] = rowSums(pchi)[3] 
    chi2avgs[4] = rowSums(pchi)[4] 
    chi2avgs[5] = rowSums(pchi)[5] 

> head(chi2avgs) 
[1] 136.476367 3.112781 75.416334 9.481914 2.638835 0.000000

我不知道是什么原因导致这个问题。你有一个想法如何解决它？

来源

2017-09-20 Diana01

您可以直接尝试rowsums没有[N]

chi2avgs = rowSums(pchi)

来源

2017-09-20 16:03:32 Sab

合作。我爱你！ – Diana01

A for循环与rowSums功能

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