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rrowssubtraction

r how to subtract elements of different length matrices


I've got two dataframes that have same number of rows (22 rows) and different number of columns.

sim_10(22 rows, 15 columns):

2    0.577967    0.023869   0.021571    0.481754    0.61584     0    0   0  0  0     0.024057    0.014209   1    0.085784


8   0.0775       0.274113   2.7e-05     0.01215     0.009345    0    0  0   0   0   0.004092     0.00784    0     0

And how can I do it in easy way.. ...

nm_10(22 rows, 8 columns)

11  0.926554    0.256966    0.859375    0   0.191011    0   0           0
2   0.858757    0.256966    0.21875     0   0.662921    0   0.845506    0.090909
 ..

the first column of two dataframes are same just in different order(names of cases). I need to find the matching row names in nm_10 and sm_10 and subtract every element of sm_10 in that row to the every element in the nm_10. example:

for '2' sm_nm_10:

  2 (0.577967-0.858757=-0.28079)    (0.577967-0.256966=)    (0.577967-0.21875)  ...(0.577967-0.090909=..)

    (0.023869-0.858757=)    (0.023869-0.256966=)    (0.023869-0.21875)  ...(0.023869-0.090909=..)

 ....

(0.085784-0.858757=)    (0.085784-0.256966=)    (0.085784-0.21875)  ...(0.085784-0.090909=..)

and that for all data. Check every row's first column, find matching row and do operation. Is there any simple way to do it? I looked into sweep, apply but couldn't figure out how to use them. I keep getting errors referring to length etc. I decided to keep it simple and here is what I have :

s = numeric()

for (i in 1:nrow(sm_10))
{
for (jj in 1:nrow(nm_10))
{ 
 for (j in 2:ncol(nm_10))
 {
  for (ii in 2:ncol(sm_10))
 {
 sm_10[i,]%in% nm_10[jj,]

s <- sm_10[,ii]-nm_10[,j]
  }}}}

What is wrong here? Could anyone explain and suggest better?

UPDATE:

The end result I need is all rows 22 with the elements subtractions. that is 22 rows with (14*7 ) columns..


Solution

  • I think the best solution here is to replicate the LHS by a sufficient multiplier such that it will then possess the desired output width, and then simply subtract the RHS from it. This will naturally be a vectorized subtraction and will cycle the RHS a sufficient number of times to fully cover the widened LHS. We must just take care to ensure that the pairing of elements is correct, which requires two things: (1) reorder the rows of the RHS such that the key values align with the LHS, and (2) replicate the LHS using the each parameter of rep(), rather than the times parameter:

    df1 <- as.data.frame(cbind(sample(1:22),matrix(1:(22*14),22)));
    df2 <- as.data.frame(cbind(sample(1:22),matrix(1:(22*7),22)));
    df1;
    ##    V1 V2 V3 V4 V5  V6  V7  V8  V9 V10 V11 V12 V13 V14 V15
    ## 1  22  1 23 45 67  89 111 133 155 177 199 221 243 265 287
    ## 2  20  2 24 46 68  90 112 134 156 178 200 222 244 266 288
    ## 3  13  3 25 47 69  91 113 135 157 179 201 223 245 267 289
    ## 4  12  4 26 48 70  92 114 136 158 180 202 224 246 268 290
    ## 5  16  5 27 49 71  93 115 137 159 181 203 225 247 269 291
    ## 6   7  6 28 50 72  94 116 138 160 182 204 226 248 270 292
    ## 7   1  7 29 51 73  95 117 139 161 183 205 227 249 271 293
    ## 8   2  8 30 52 74  96 118 140 162 184 206 228 250 272 294
    ## 9   9  9 31 53 75  97 119 141 163 185 207 229 251 273 295
    ## 10 14 10 32 54 76  98 120 142 164 186 208 230 252 274 296
    ## 11  4 11 33 55 77  99 121 143 165 187 209 231 253 275 297
    ## 12 21 12 34 56 78 100 122 144 166 188 210 232 254 276 298
    ## 13 15 13 35 57 79 101 123 145 167 189 211 233 255 277 299
    ## 14 10 14 36 58 80 102 124 146 168 190 212 234 256 278 300
    ## 15  8 15 37 59 81 103 125 147 169 191 213 235 257 279 301
    ## 16  6 16 38 60 82 104 126 148 170 192 214 236 258 280 302
    ## 17 19 17 39 61 83 105 127 149 171 193 215 237 259 281 303
    ## 18  3 18 40 62 84 106 128 150 172 194 216 238 260 282 304
    ## 19  5 19 41 63 85 107 129 151 173 195 217 239 261 283 305
    ## 20 18 20 42 64 86 108 130 152 174 196 218 240 262 284 306
    ## 21 17 21 43 65 87 109 131 153 175 197 219 241 263 285 307
    ## 22 11 22 44 66 88 110 132 154 176 198 220 242 264 286 308
    df2;
    ##    V1 V2 V3 V4 V5  V6  V7  V8
    ## 1   6  1 23 45 67  89 111 133
    ## 2  17  2 24 46 68  90 112 134
    ## 3  12  3 25 47 69  91 113 135
    ## 4  20  4 26 48 70  92 114 136
    ## 5  13  5 27 49 71  93 115 137
    ## 6  10  6 28 50 72  94 116 138
    ## 7  16  7 29 51 73  95 117 139
    ## 8  15  8 30 52 74  96 118 140
    ## 9  21  9 31 53 75  97 119 141
    ## 10 22 10 32 54 76  98 120 142
    ## 11  1 11 33 55 77  99 121 143
    ## 12 18 12 34 56 78 100 122 144
    ## 13  9 13 35 57 79 101 123 145
    ## 14  4 14 36 58 80 102 124 146
    ## 15 11 15 37 59 81 103 125 147
    ## 16 19 16 38 60 82 104 126 148
    ## 17  8 17 39 61 83 105 127 149
    ## 18  5 18 40 62 84 106 128 150
    ## 19  3 19 41 63 85 107 129 151
    ## 20  7 20 42 64 86 108 130 152
    ## 21  2 21 43 65 87 109 131 153
    ## 22 14 22 44 66 88 110 132 154
    cbind(df1[,1],as.data.frame(rep(df1[,-1],each=ncol(df2)-1))-as.matrix(df2[match(df1[,1],df2[,1]),-1]));
    ##    df1[, 1]  V2 V2.1 V2.2 V2.3 V2.4 V2.5 V2.6 V3 V3.1 V3.2 V3.3 V3.4 V3.5 V3.6 V4 V4.1 V4.2 V4.3 V4.4 V4.5 V4.6 V5 V5.1 V5.2 V5.3 V5.4 V5.5 V5.6  V6 V6.1 V6.2 V6.3 V6.4 V6.5 V6.6  V7 V7.1 V7.2 V7.3 V7.4 V7.5 V7.6  V8 V8.1 V8.2 V8.3 V8.4 V8.5 V8.6  V9 V9.1 V9.2 V9.3 V9.4 V9.5 V9.6 V10 V10.1 V10.2 V10.3 V10.4 V10.5 V10.6 V11 V11.1 V11.2 V11.3 V11.4 V11.5 V11.6 V12 V12.1 V12.2 V12.3 V12.4 V12.5 V12.6 V13 V13.1 V13.2 V13.3 V13.4 V13.5 V13.6 V14 V14.1 V14.2 V14.3 V14.4 V14.5 V14.6 V15 V15.1 V15.2 V15.3 V15.4 V15.5 V15.6
    ## 1        22  -9  -31  -53  -75  -97 -119 -141 13   -9  -31  -53  -75  -97 -119 35   13   -9  -31  -53  -75  -97 57   35   13   -9  -31  -53  -75  79   57   35   13   -9  -31  -53 101   79   57   35   13   -9  -31 123  101   79   57   35   13   -9 145  123  101   79   57   35   13 167   145   123   101    79    57    35 189   167   145   123   101    79    57 211   189   167   145   123   101    79 233   211   189   167   145   123   101 255   233   211   189   167   145   123 277   255   233   211   189   167   145
    ## 2        20  -2  -24  -46  -68  -90 -112 -134 20   -2  -24  -46  -68  -90 -112 42   20   -2  -24  -46  -68  -90 64   42   20   -2  -24  -46  -68  86   64   42   20   -2  -24  -46 108   86   64   42   20   -2  -24 130  108   86   64   42   20   -2 152  130  108   86   64   42   20 174   152   130   108    86    64    42 196   174   152   130   108    86    64 218   196   174   152   130   108    86 240   218   196   174   152   130   108 262   240   218   196   174   152   130 284   262   240   218   196   174   152
    ## 3        13  -2  -24  -46  -68  -90 -112 -134 20   -2  -24  -46  -68  -90 -112 42   20   -2  -24  -46  -68  -90 64   42   20   -2  -24  -46  -68  86   64   42   20   -2  -24  -46 108   86   64   42   20   -2  -24 130  108   86   64   42   20   -2 152  130  108   86   64   42   20 174   152   130   108    86    64    42 196   174   152   130   108    86    64 218   196   174   152   130   108    86 240   218   196   174   152   130   108 262   240   218   196   174   152   130 284   262   240   218   196   174   152
    ## 4        12   1  -21  -43  -65  -87 -109 -131 23    1  -21  -43  -65  -87 -109 45   23    1  -21  -43  -65  -87 67   45   23    1  -21  -43  -65  89   67   45   23    1  -21  -43 111   89   67   45   23    1  -21 133  111   89   67   45   23    1 155  133  111   89   67   45   23 177   155   133   111    89    67    45 199   177   155   133   111    89    67 221   199   177   155   133   111    89 243   221   199   177   155   133   111 265   243   221   199   177   155   133 287   265   243   221   199   177   155
    ## 5        16  -2  -24  -46  -68  -90 -112 -134 20   -2  -24  -46  -68  -90 -112 42   20   -2  -24  -46  -68  -90 64   42   20   -2  -24  -46  -68  86   64   42   20   -2  -24  -46 108   86   64   42   20   -2  -24 130  108   86   64   42   20   -2 152  130  108   86   64   42   20 174   152   130   108    86    64    42 196   174   152   130   108    86    64 218   196   174   152   130   108    86 240   218   196   174   152   130   108 262   240   218   196   174   152   130 284   262   240   218   196   174   152
    ## 6         7 -14  -36  -58  -80 -102 -124 -146  8  -14  -36  -58  -80 -102 -124 30    8  -14  -36  -58  -80 -102 52   30    8  -14  -36  -58  -80  74   52   30    8  -14  -36  -58  96   74   52   30    8  -14  -36 118   96   74   52   30    8  -14 140  118   96   74   52   30    8 162   140   118    96    74    52    30 184   162   140   118    96    74    52 206   184   162   140   118    96    74 228   206   184   162   140   118    96 250   228   206   184   162   140   118 272   250   228   206   184   162   140
    ## 7         1  -4  -26  -48  -70  -92 -114 -136 18   -4  -26  -48  -70  -92 -114 40   18   -4  -26  -48  -70  -92 62   40   18   -4  -26  -48  -70  84   62   40   18   -4  -26  -48 106   84   62   40   18   -4  -26 128  106   84   62   40   18   -4 150  128  106   84   62   40   18 172   150   128   106    84    62    40 194   172   150   128   106    84    62 216   194   172   150   128   106    84 238   216   194   172   150   128   106 260   238   216   194   172   150   128 282   260   238   216   194   172   150
    ## 8         2 -13  -35  -57  -79 -101 -123 -145  9  -13  -35  -57  -79 -101 -123 31    9  -13  -35  -57  -79 -101 53   31    9  -13  -35  -57  -79  75   53   31    9  -13  -35  -57  97   75   53   31    9  -13  -35 119   97   75   53   31    9  -13 141  119   97   75   53   31    9 163   141   119    97    75    53    31 185   163   141   119    97    75    53 207   185   163   141   119    97    75 229   207   185   163   141   119    97 251   229   207   185   163   141   119 273   251   229   207   185   163   141
    ## 9         9  -4  -26  -48  -70  -92 -114 -136 18   -4  -26  -48  -70  -92 -114 40   18   -4  -26  -48  -70  -92 62   40   18   -4  -26  -48  -70  84   62   40   18   -4  -26  -48 106   84   62   40   18   -4  -26 128  106   84   62   40   18   -4 150  128  106   84   62   40   18 172   150   128   106    84    62    40 194   172   150   128   106    84    62 216   194   172   150   128   106    84 238   216   194   172   150   128   106 260   238   216   194   172   150   128 282   260   238   216   194   172   150
    ## 10       14 -12  -34  -56  -78 -100 -122 -144 10  -12  -34  -56  -78 -100 -122 32   10  -12  -34  -56  -78 -100 54   32   10  -12  -34  -56  -78  76   54   32   10  -12  -34  -56  98   76   54   32   10  -12  -34 120   98   76   54   32   10  -12 142  120   98   76   54   32   10 164   142   120    98    76    54    32 186   164   142   120    98    76    54 208   186   164   142   120    98    76 230   208   186   164   142   120    98 252   230   208   186   164   142   120 274   252   230   208   186   164   142
    ## 11        4  -3  -25  -47  -69  -91 -113 -135 19   -3  -25  -47  -69  -91 -113 41   19   -3  -25  -47  -69  -91 63   41   19   -3  -25  -47  -69  85   63   41   19   -3  -25  -47 107   85   63   41   19   -3  -25 129  107   85   63   41   19   -3 151  129  107   85   63   41   19 173   151   129   107    85    63    41 195   173   151   129   107    85    63 217   195   173   151   129   107    85 239   217   195   173   151   129   107 261   239   217   195   173   151   129 283   261   239   217   195   173   151
    ## 12       21   3  -19  -41  -63  -85 -107 -129 25    3  -19  -41  -63  -85 -107 47   25    3  -19  -41  -63  -85 69   47   25    3  -19  -41  -63  91   69   47   25    3  -19  -41 113   91   69   47   25    3  -19 135  113   91   69   47   25    3 157  135  113   91   69   47   25 179   157   135   113    91    69    47 201   179   157   135   113    91    69 223   201   179   157   135   113    91 245   223   201   179   157   135   113 267   245   223   201   179   157   135 289   267   245   223   201   179   157
    ## 13       15   5  -17  -39  -61  -83 -105 -127 27    5  -17  -39  -61  -83 -105 49   27    5  -17  -39  -61  -83 71   49   27    5  -17  -39  -61  93   71   49   27    5  -17  -39 115   93   71   49   27    5  -17 137  115   93   71   49   27    5 159  137  115   93   71   49   27 181   159   137   115    93    71    49 203   181   159   137   115    93    71 225   203   181   159   137   115    93 247   225   203   181   159   137   115 269   247   225   203   181   159   137 291   269   247   225   203   181   159
    ## 14       10   8  -14  -36  -58  -80 -102 -124 30    8  -14  -36  -58  -80 -102 52   30    8  -14  -36  -58  -80 74   52   30    8  -14  -36  -58  96   74   52   30    8  -14  -36 118   96   74   52   30    8  -14 140  118   96   74   52   30    8 162  140  118   96   74   52   30 184   162   140   118    96    74    52 206   184   162   140   118    96    74 228   206   184   162   140   118    96 250   228   206   184   162   140   118 272   250   228   206   184   162   140 294   272   250   228   206   184   162
    ## 15        8  -2  -24  -46  -68  -90 -112 -134 20   -2  -24  -46  -68  -90 -112 42   20   -2  -24  -46  -68  -90 64   42   20   -2  -24  -46  -68  86   64   42   20   -2  -24  -46 108   86   64   42   20   -2  -24 130  108   86   64   42   20   -2 152  130  108   86   64   42   20 174   152   130   108    86    64    42 196   174   152   130   108    86    64 218   196   174   152   130   108    86 240   218   196   174   152   130   108 262   240   218   196   174   152   130 284   262   240   218   196   174   152
    ## 16        6  15   -7  -29  -51  -73  -95 -117 37   15   -7  -29  -51  -73  -95 59   37   15   -7  -29  -51  -73 81   59   37   15   -7  -29  -51 103   81   59   37   15   -7  -29 125  103   81   59   37   15   -7 147  125  103   81   59   37   15 169  147  125  103   81   59   37 191   169   147   125   103    81    59 213   191   169   147   125   103    81 235   213   191   169   147   125   103 257   235   213   191   169   147   125 279   257   235   213   191   169   147 301   279   257   235   213   191   169
    ## 17       19   1  -21  -43  -65  -87 -109 -131 23    1  -21  -43  -65  -87 -109 45   23    1  -21  -43  -65  -87 67   45   23    1  -21  -43  -65  89   67   45   23    1  -21  -43 111   89   67   45   23    1  -21 133  111   89   67   45   23    1 155  133  111   89   67   45   23 177   155   133   111    89    67    45 199   177   155   133   111    89    67 221   199   177   155   133   111    89 243   221   199   177   155   133   111 265   243   221   199   177   155   133 287   265   243   221   199   177   155
    ## 18        3  -1  -23  -45  -67  -89 -111 -133 21   -1  -23  -45  -67  -89 -111 43   21   -1  -23  -45  -67  -89 65   43   21   -1  -23  -45  -67  87   65   43   21   -1  -23  -45 109   87   65   43   21   -1  -23 131  109   87   65   43   21   -1 153  131  109   87   65   43   21 175   153   131   109    87    65    43 197   175   153   131   109    87    65 219   197   175   153   131   109    87 241   219   197   175   153   131   109 263   241   219   197   175   153   131 285   263   241   219   197   175   153
    ## 19        5   1  -21  -43  -65  -87 -109 -131 23    1  -21  -43  -65  -87 -109 45   23    1  -21  -43  -65  -87 67   45   23    1  -21  -43  -65  89   67   45   23    1  -21  -43 111   89   67   45   23    1  -21 133  111   89   67   45   23    1 155  133  111   89   67   45   23 177   155   133   111    89    67    45 199   177   155   133   111    89    67 221   199   177   155   133   111    89 243   221   199   177   155   133   111 265   243   221   199   177   155   133 287   265   243   221   199   177   155
    ## 20       18   8  -14  -36  -58  -80 -102 -124 30    8  -14  -36  -58  -80 -102 52   30    8  -14  -36  -58  -80 74   52   30    8  -14  -36  -58  96   74   52   30    8  -14  -36 118   96   74   52   30    8  -14 140  118   96   74   52   30    8 162  140  118   96   74   52   30 184   162   140   118    96    74    52 206   184   162   140   118    96    74 228   206   184   162   140   118    96 250   228   206   184   162   140   118 272   250   228   206   184   162   140 294   272   250   228   206   184   162
    ## 21       17  19   -3  -25  -47  -69  -91 -113 41   19   -3  -25  -47  -69  -91 63   41   19   -3  -25  -47  -69 85   63   41   19   -3  -25  -47 107   85   63   41   19   -3  -25 129  107   85   63   41   19   -3 151  129  107   85   63   41   19 173  151  129  107   85   63   41 195   173   151   129   107    85    63 217   195   173   151   129   107    85 239   217   195   173   151   129   107 261   239   217   195   173   151   129 283   261   239   217   195   173   151 305   283   261   239   217   195   173
    ## 22       11   7  -15  -37  -59  -81 -103 -125 29    7  -15  -37  -59  -81 -103 51   29    7  -15  -37  -59  -81 73   51   29    7  -15  -37  -59  95   73   51   29    7  -15  -37 117   95   73   51   29    7  -15 139  117   95   73   51   29    7 161  139  117   95   73   51   29 183   161   139   117    95    73    51 205   183   161   139   117    95    73 227   205   183   161   139   117    95 249   227   205   183   161   139   117 271   249   227   205   183   161   139 293   271   249   227   205   183   161
    

    For a demo that's easier to verify by eye, here I'll use three rows, five data columns on the LHS, and two data columns on the RHS:

    df1 <- as.data.frame(cbind(sample(1:3),matrix(1:(3*5),3)));
    df2 <- as.data.frame(cbind(sample(1:3),matrix(1:(3*2),3)));
    df1;
    ##   V1 V2 V3 V4 V5 V6
    ## 1  3  1  4  7 10 13
    ## 2  1  2  5  8 11 14
    ## 3  2  3  6  9 12 15
    df2;
    ##   V1 V2 V3
    ## 1  3  1  4
    ## 2  2  2  5
    ## 3  1  3  6
    cbind(df1[,1],as.data.frame(rep(df1[,-1],each=ncol(df2)-1))-as.matrix(df2[match(df1[,1],df2[,1]),-1]));
    ##   df1[, 1] V2 V2.1 V3 V3.1 V4 V4.1 V5 V5.1 V6 V6.1
    ## 1        3  0   -3  3    0  6    3  9    6 12    9
    ## 2        1 -1   -4  2   -1  5    2  8    5 11    8
    ## 3        2  1   -2  4    1  7    4 10    7 13   10
    

    Notes:

    • Since the subtraction step must exclude the key column, rep() must operate on df1[,-1]. The -1 column subscript excludes the key column, which is assumed to be the first column in the data.frame.
    • The argument to each must be the number of subtrahends for each minuend, which means it also must exclude the key by subtracting one from ncol(df2).
    • Technically, when given a data.frame, rep() operates component-wise on the underlying list. But this works out for our purposes, because we can coerce back to data.frame with a call to as.data.frame(), and it's as if each individual element was replicated horizontally within its row. We are then ready with the widened data.frame to serve as the LHS of the subtraction.
    • In order to reorder the rows of the RHS, we first need to derive the correct row order. This can be done with match(df1[,1],df2[,1]). This basically says "for each key value in df1 in the order they occur in df1, return the row index in which that key value can be found in df2." The resulting index vector can then be used to row-index df2 to order it to align with df1. In the same index operation, we can exclude the key column of df2, fully preparing it for the cyclic subtraction, thus we have df2[match(df1[,1],df2[,1]),-1].
    • Unfortunately, it is not possible to subtract data.frames from each other, unless they are identical in size (otherwise you get the error ‘-’ only defined for equally-sized data frames). Thus I had to add an as.matrix() call on the RHS before subtracting. Another possible solution here could be to replicate the RHS to match the size of the LHS.
    • The key column had to be "restored" after the subtraction, hence the cbind() call wrapping the subtraction, which prepends the key column from df1 (df1[,1]).
    • I didn't bother to set any column names, since you haven't specified a requirement for them in your question. You can set them afterward if necessary via names()/setNames()/colnames()/dimnames().