[R] merge multiple data frames

Thu Jan 26 18:29:18 CET 2012

This is my reproducible example (three data frames: a, b, c)

a<-structure(list(date = structure(1:6, .Label = c("2012-01-03", 
"2012-01-04", "2012-01-05", "2012-01-06", "2012-01-07", "2012-01-08", 
"2012-01-09", "2012-01-10", "2012-01-11", "2012-01-12", "2012-01-13", 
"2012-01-14", "2012-01-15", "2012-01-16", "2012-01-17", "2012-01-18", 
"2012-01-19", "2012-01-20", "2012-01-21", "2012-01-22", "2012-01-23"
), class = "factor"), so2 = c(0.799401398190476, 0, 0, 0.0100453950434783, 
0.200154920565217, 0.473866969181818), nox = c(111.716109973913, 
178.077239330435, 191.257829021739, 50.6799951473913, 115.284643540435, 
110.425185027727), no = c(48.8543691516522, 88.7197448817391, 
93.9931932472609, 13.9759949817391, 43.1395266865217, 41.7280296016364
), no2 = c(36.8673432865217, 42.37150668, 47.53311701, 29.3026882474783, 
49.2986070321739, 46.5978461731818), co = c(0.618856168125,
0.996593475083333, 
0.666987416083333, 0.383437311166667, 0.281604928875, 0.155383408913043
), o3 = c(12.1393100029167, 12.3522739816522, 10.9908791203043, 
26.9122200013043, 13.8421695947826, 12.3788847045455), ipa =
c(167.541954974667, 
252.7196257875, 231.802370709167, 83.4850259595833, 174.394613581667, 
173.868599272609), ws = c(1.47191016429167, 0.765781205208333, 
0.937053086791667, 1.581022406625, 0.909756802125, 0.959252831695652
), wd = c(45.2650019737732, 28.2493544114369, 171.049080544214, 
319.753674830936, 33.8713897347193, 228.368119533759), temp =
c(7.91972825883333, 
3.79434291520833, 2.1287644735, 6.733854600625, 3.136579722, 
3.09864120704348), umr = c(86.11566638875, 94.5034087491667, 
94.14451249375, 53.1016709004167, 65.63420423, 74.955669236087
)), .Names = c("date", "so2", "nox", "no", "no2", "co", "o3", 
"ipa", "ws", "wd", "temp", "umr"), row.names = c(NA, 6L), class =
"data.frame")

b<-structure(list(date = structure(1:6, .Label = c("2012-01-03", 
"2012-01-04", "2012-01-05", "2012-01-06", "2012-01-07", "2012-01-08", 
"2012-01-09", "2012-01-10", "2012-01-11", "2012-01-12", "2012-01-13", 
"2012-01-14", "2012-01-15", "2012-01-16", "2012-01-17", "2012-01-18", 
"2012-01-19", "2012-01-20", "2012-01-21", "2012-01-22", "2012-01-23"
), class = "factor"), so2 = c(0, 0, 0, 0, 0, 0), nox = c(13.74758511, 
105.8060582, 61.22720599, 11.45280354, 56.86804174, 39.17917222
), no = c(0.882593766, 48.97037506, 9.732937217, 1.794549972, 
16.32300019, 8.883637786), no2 = c(11.80447753, 25.35235381, 
28.72990261, 8.590004034, 31.9003796, 25.50512403), co = c(0.113954917, 
0.305985964, 0.064001839, 0, 1.86e-05, 0), o3 = c(5.570499897, 
9.802379608, 5.729360104, 11.91304016, 12.13407993, 10.00961971
), ipa = c(6.065110207, 116.9079971, 93.21240234, 10.5777998, 
66.40740204, 34.47359848), ws = c(0.122115001, 0.367668003, 0.494913995, 
0.627124012, 0.473895013, 0.593913019), wd = c(238.485119317031, 
221.645073036776, 220.372076815032, 237.868340917096, 209.532933617465, 
215.752030286564), temp = c(4.044159889, 1.176810026, 0.142934993, 
0.184606999, -0.935989976, -2.015399933), umr = c(72.29229736, 
88.69879913, 87.49530029, 24.00079918, 44.8852005, 49.47729874
)), .Names = c("date", "so2", "nox", "no", "no2", "co", "o3", 
"ipa", "ws", "wd", "temp", "umr"), row.names = c(NA, 6L), class =
"data.frame")

c<-structure(list(date = structure(1:6, .Label = c("2012-01-03", 
"2012-01-04", "2012-01-05", "2012-01-06", "2012-01-07", "2012-01-08", 
"2012-01-09", "2012-01-10", "2012-01-11", "2012-01-12", "2012-01-13", 
"2012-01-14", "2012-01-15", "2012-01-16", "2012-01-17", "2012-01-18", 
"2012-01-19", "2012-01-20", "2012-01-21", "2012-01-22", "2012-01-23"
), class = "factor"), so2 = c(2.617839247, 0, 0, 0.231044086, 
0.944608887, 2.12400444), nox = c(308.9046313, 275.6778849, 390.0824142, 
178.7429364, 238.655832, 251.892601), no = c(156.0262489, 151.4412498, 
221.0725021, 65.96049786, 106.541748, 119.3471241), no2 = c(74.80145447, 
59.29991481, 66.5897975, 77.84267978, 75.68422569, 85.43044816
), co = c(1.628431197, 1.716231492, 1.264678366, 1.693460745, 
0.780637084, 0.892724398), o3 = c(26.1473999, 15.91584015, 22.46199989, 
37.39400101, 15.63426018, 17.51494026), ipa = c(538.414978, 406.4620056, 
432.6459961, 275.2820129, 435.7909851, 436.8039856), ws = c(4.995530128, 
1.355309963, 1.708899975, 3.131690025, 1.546270013, 1.571320057
), wd = c(58.15639877, 64.5657153143848, 39.9754269501381, 24.0739884380921, 
55.9453098437477, 56.7648829092446), temp = c(10.24740028, 7.052690029, 
4.33258009, 13.91609955, 8.762220383, 11.04300022), umr = c(97.60900116, 
96.91899872, 96.20649719, 94.74620056, 82.04550171, 89.41320038
)), .Names = c("date", "so2", "nox", "no", "no2", "co", "o3", 
"ipa", "ws", "wd", "temp", "umr"), row.names = c(NA, 6L), class =
"data.frame")

Given the three data frames “a”, “b” and “c”, I need to merge them all by
the common field “date”.
The following attempt is working fine but…

# code start
all<-merge(a,b,by="date",suffixes=c(".a",".b"),all=T)
all<-merge(all,c,by="date",all=T)
# code end

…I would like to possibly do it in just “one shot” (a generalisation of the
code for a more complex case of handling many data frames) also by assigning
proper suffixes to each variable (not possible with the previous code
snippet)

Then I also try a different approach with the use of the library reshape and
the function “merge_all” but…

# code start
library("reshape")
all.new<-merge_all(a, b, c, by="date", all=T, suffixes=c(".a",".b",".c"))
# code end

…I got the following error message:
error in merge in merge.data.frame(as.data.frame(x), as.data.frame(y), ...)
: 
  formal argument "all" associated to different argument passed
(a free translation from italian)

My question is: 
how to accomplish the merging of multiple data frames with all the same
variable names and by a single id field with the need of “keeping track” of
the original data frame by means of the use of suffixes appended to new
variables?

Any help much appreciated

Thank you

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