Hello All,
I have a data frame (dput information below) with food item weight for fish
species.
I need to calculate the Mean proportion by weight of each food item for
each specie, as show in solution data frame (dput information below).
I use the ddply function (plyr package) in two steps. First calculate the
proportion of weight for each individual:
step1 = ddply (example, .(ID), transform, Wi = round (Weight/sum (Weight),
2))
Then, I use lenght (unique (ID)) to calculate the mean of each food item
for each specie:
step2 = ddply (step1, .(Specie, Food.item), summarise, MWi = sum
(Wi)/length (unique(ID)))
I do not understand why this didn't work. Someone can help me?
Thanks in advanced!
*EXAMPLE*
structure(list(ID = c(779L, 782L, 1717L, 1717L, 1717L, 1803L,
2650L, 2650L, 2700L, 2700L, 3611L, 3613L, 3647L, 3654L, 3654L,
3683L, 3683L, 3683L, 3685L, 3997L), Site = c("Três Marias", "Três Marias",
"Nova Ponte", "Nova Ponte", "Nova Ponte", "Três Marias", "São Simão",
"São Simão", "São Simão", "São Simão", "São Simão", "São Simão",
"São Simão", "São Simão", "São Simão", "São Simão", "São Simão",
"São Simão", "São Simão", "São Simão"), Specie = c("Acestrorhynchus
lacustris",
"Acestrorhynchus lacustris", "Acestrorhynchus lacustris", "Acestrorhynchus
lacustris",
"Acestrorhynchus lacustris", "Acestrorhynchus lacustris", "Schizodon
intermedius",
"Schizodon intermedius", "Schizodon intermedius", "Schizodon intermedius",
"Schizodon intermedius", "Schizodon intermedius", "Schizodon intermedius",
"Schizodon intermedius", "Schizodon intermedius", "Schizodon intermedius",
"Schizodon intermedius", "Schizodon intermedius", "Schizodon intermedius",
"Schizodon intermedius"), Weight = c(0.06, 0.01, 0.01, 0.33, 0.01,
3.5, 0.01, 0.04, 0.01, 0.01, 0.38, 0.29, 0.04, 0.03, 0.11, 0.04,
0.04, 0.03, 0.01, 0.01), Food.item = c("Fish", "Vegetal", "Alga",
"MNI", "Sediment", "Fish", "Alga", "MNI", "Alga", "MNI", "Vegetal",
"Vegetal", "Vegetal", "Alga", "Vegetal", "Alga", "MNI", "Sediment",
"Sediment", "Vegetal")), .Names = c("ID", "Site", "Specie",
"Weight", "Food.item"), row.names = c(1869113L, 2290407L, 56668L,
1485394L, 2126489L, 368143L, 57601L, 1486327L, 57651L, 1486377L,
2348187L, 2348189L, 2293272L, 58605L, 2293279L, 40317L, 1487360L,
2128455L, 2128457L, 2293622L), class = "data.frame")
*SOLUTION*
structure(list(Specie = c("Acestrorhynchus lacustris", "Acestrorhynchus
lacustris",
"Acestrorhynchus lacustris", "Acestrorhynchus lacustris", "Acestrorhynchus
lacustris",
"Schizodon intermedius", "Schizodon intermedius", "Schizodon intermedius",
"Schizodon intermedius"), Food.item = c("Peixe", "Vegetal", "Alga",
"MNI", "Sedimento", "Alga", "MNI", "Vegetal", "Sedimento"), MWi = c("0.5",
"0.25", "0.0075", "0.235", "0.0075", "0.141111111", "0.184444444",
"0.532222222", "0.141111111")), .Names = c("Specie", "Food.item",
"MWi"), class = "data.frame", row.names = c(NA, -9L))
*
*
sessionInfo()
R version 2.15.2 (2012-10-26)
Platform: i386-w64-mingw32/i386 (32-bit)
Windows XP
*
*
--
Raoni Rosa Rodrigues
Research Associate of Fish Transposition Center CTPeixes
Universidade Federal de Minas Gerais - UFMG
Brasil
rodrigues.ra...@gmail.com
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