On Nov 29, 2011, at 1:08 AM, Katrina Bennett wrote:
> I'd like to sum a matrix only where the matrix meets a specific
> condition.
> The matrix has 365 rows and about 50,000 columns.
If you describe the meaning attached to the data if might help readers
understand what the acceptable options might be. (Please read the
Posting Guide.)
>
> str(cdem.mat.yr)
> num [1:365, 1:41772] -43.5 -48.4 -45.9 -38.4 -32 ...
>
> I'm having trouble replicating this because it is not working out
> for me,
> so I'm unsure I can provide an solid working example (apologies).
>
> I would like to subset my matrix where the values are greater than
> zero. I
> can do this easily using the following command to generate a matrix of
> TRUE/FALSE conditions.
>
> thaw.index <- subset(cdem.mat.yr > 0)
Are you hoping to subset particular rows?
If not, then you can make a copy and then set the negative values to NA
thaw.mat <-cdem.mat.yr
is.na(thaw.mat)<- thaw.mat < 0
and ...
rowSums(thaw.mat, na.rm=TRUE)
>
> However, every time I then try to run apply, or rowSums to sum the
> matrix
> rows using this index, I get back errors messages or the wrong answer.
I am guessing that your subset operation produced a vector and that
apply or rowSums no longer makes any sense.
> There is a lot of values that meet this condition, so I know this
> issue is
> with my formatting of the argument.
>
> i.e.
> rowSums(cdem.mat.yr == thaw.index)
> [1] 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
> 0 0 0
> 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
> [66] 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
> 0 0 0
> 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
> [131] 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
> 0 0 0 0
> 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
> [196] 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
> 0 0 0 0
> 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
> [261] 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
> 0 0 0 0
> 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
> [326] 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
> 0 0 0 0
> 0 0 0 0 0
>
> thaw.index.sum <- apply(cdem.mat.yr[which(cdem.mat.yr > 0)], 1, sum)
> Error in apply(cdem.mat.yr[which(cdem.mat.yr > 0)], 1, sum) :
> dim(X) must have a positive length
>
> This just provides me with one single value (I want the sum of all
> the rows
> individually)
> sum(apply(cdem.mat.yr, 1, function(x) x>0))
>
> If I only run the apply over the entire matrix, this works but I can't
> subset it according to my condition.
>
> apply(cdem.mat.yr, 1, sum)
> [1] -1834000.521 -2038684.652 -1932676.585 -1619369.113 -1353598.426
> -1190377.640 -1263541.796 -1438280.178 -1472440.385 -1714465.774
> [11] -1945920.377 -2163888.712 -1836656.208 -1772994.790 -1864650.604
> -1633144.043 -1580619.187 -1684046.620 -1769963.843 -1787676.116
> [21] -1643345.342 -1497455.795 -1580307.433 -1483559.628 -1531067.546
> -1557093.271 -1363626.528 -1160882.203 -1118893.494 -1352922.958
> [31] -1441715.250 -1539084.024 -1717835.433 -1806727.136 -1887120.912
> -1645721.673 -1310700.520 -1531408.644 -1582011.715 -1460538.996
> [41] -1192880.165 -1211111.092 -1190390.732 -1241594.368 -1180704.394
> -1025346.594 -1073581.060 -889662.991 -798735.050 -784632.707
> [51] -874676.120 -957186.890 -1054610.980 -1067208.121 -1222859.353
> -1477327.599 -1635653.310 -1696308.770 -1473630.951 -1283105.867
> [61] -1061390.704 -811017.224 -875804.422 -851608.811 -948160.325
> -1440351.359 -1206523.958 -1143659.246 -1405071.144 -1421438.254
> [71] -1374929.105 -1336184.952 -1237185.588 -1082307.120 -1019742.616
> -958257.706 -888078.311 -790481.841 -821010.686 -907205.025
> [81] -966761.676 -926937.928 -908394.310 -976085.444 -971934.490
> -703952.655 -521541.649 -625973.624 -743458.875 -631452.421
> [91] -584709.631 -565843.210 -604252.152 -616885.977 -522011.655
> -576824.263 -726170.003 -822902.735 -897385.940 -668897.194
> [101] -525227.323 -493291.723 -559480.809 -627790.133 -607923.974
> -535240.664 -346627.878 -343257.607 -287171.179 -324723.615
> [111] -389052.208 -420393.385 -498589.819 -542040.688 -394442.745
> -183163.637 -126540.029 -186213.012 -179799.971 -364410.639
> [121] -309555.880 -357052.251 -321362.137 -394878.460 -498785.071
> -309942.686 -276417.534 -337700.381 -304804.510 -238100.600
> [131] -261210.843 -201821.616 -299377.673 -232015.614 -121752.676
> -154925.661 -145809.729 15840.738 145755.754 -33601.212
> [141] -24323.630 35036.731 55156.441 48603.824 87203.646
> 139653.449 111722.558 101036.307 153884.464 153151.263
> [151] 112680.914 108730.812 110198.055 127087.033 77174.238
> -67632.638 -35129.976 56801.006 6712.631 8838.200
> [161] 40086.874 -29691.225 -55861.564 7561.504 91232.944
> 31752.447 1694.756 -43835.544 2522.883 41727.218
> [171] 26918.990 128692.011 114752.327 131455.862 127149.113
> 144686.214 160344.465 102204.088 130322.785 70392.818
> [181] 100384.523 210138.826 230235.443 211137.595 199770.103
> 167185.988 103951.789 125589.859 224791.286 302672.172
> [191] 268148.251 258709.018 263356.469 122460.767 103103.124
> 1996.530 55150.667 148763.608 188425.704 172693.650
> [201] 173253.653 101070.947 142112.846 112317.201 101550.125
> 157215.618 184009.183 60265.750 94310.493 123499.949
> [211] 174061.906 247635.961 268679.388 277766.454 307758.389
> 357310.030 178755.543 127887.604 99974.033 138429.524
> [221] 119383.635 49204.240 51923.431 68469.511 63187.005
> 214353.285 394362.626 238075.491 94333.586 -13273.666
> [231] -79469.532 -40806.205 -76871.578 -49806.672 1228.690
> -38687.429 -55499.077 -102810.705 -83816.775 -60862.409
> [241] -66168.008 -78153.236 -33324.097 -92072.137 -135488.177
> -179163.704 -112465.506 -15616.185 29229.741 -34415.330
> [251] -32972.658 17278.772 -39965.022 -112357.551 -141587.923
> -105968.196 -109854.967 -133479.542 -135685.520 -173992.141
> [261] -152909.182 -131791.656 -166530.917 -228831.447 -350692.928
> -418850.501 -495572.140 -539540.225 -632322.131 -728383.982
> [271] -706613.842 -572388.522 -313981.672 -529208.500 -484367.815
> -396279.857 -424551.369 -363920.897 -357247.042 -338639.919
> [281] -298365.860 -295808.318 -296616.571 -275798.300 -378353.975
> -448394.813 -517904.514 -665762.732 -706816.178 -702220.686
> [291] -741409.378 -815699.314 -749468.808 -648206.337 -538353.298
> -507039.293 -545760.353 -752355.424 -781048.382 -700609.954
> [301] -787629.865 -920471.910 -987297.058 -1101214.452 -1164491.033
> -1233146.792 -1187575.379 -967913.570 -830991.543 -1017500.681
> [311] -1250575.007 -1416678.263 -1402879.243 -1251974.831 -1023492.832
> -1026830.185 -1293833.488 -1516913.350 -1557436.391 -1718719.068
> [321] -1725813.094 -1658967.540 -1643884.838 -1849296.409 -1891710.750
> -1623420.016 -1286998.600 -1260085.087 -1381181.790 -1191308.082
> [331] -977525.224 -1158107.546 -1270227.479 -930469.578 -526018.105
> -714733.479 -977507.860 -1207830.910 -991946.711 -769735.051
> [341] -970481.838 -1224850.395 -1349246.203 -1428091.218 -1494887.500
> -1376951.938 -1367801.367 -1353437.568 -1361260.296 -1438702.417
> [351] -1502473.526 -1652947.018 -1767153.073 -1517986.198 -1273778.527
> -1009474.240 -1000104.286 -1061987.549 -975002.278 -945633.852
> [361] -1211242.890 -1419950.962 -1533983.821 -1551817.331 -1636464.444
>
>
> Thoughts?
>
> Thank you,
> Katrina
>
> [[alternative HTML version deleted]]
>
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David Winsemius, MD
West Hartford, CT