On Aug 9, 2012, at 6:32 PM, jpm miao wrote:
Hi everyone and Achim,
Achim, I appreciate your help about the function "NCOL". When I use
"NCOL" instead of "ncol", I can find out the number of columns
(number of
time series) in the presence of only one time series (one variable,
one
column).
Now I want to know how I can find out the column names of the zoo
objects? In case of more than one time series, the function "colnames"
works, but not for the univariate time series.
> x <- sin(1:4)
> names(x) <- letters[1:4]
> z <- zoo(x)
> names(z)
[1] "a" "b" "c" "d"
--
D.
Thanks,
Miao
2012/8/9 Achim Zeileis <achim.zeil...@uibk.ac.at>
On Thu, 9 Aug 2012, jpm miao wrote:
Hi,
Part of my program is to calculate the number of time series in a
zoo
object. It works well if it has more than one time series, but it
fails if
it has only one. How can I access the number of column (i.e. the
number of
time series) when I have only one column? Why is the number of an
object
of
only one object "NULL"? It should be one, shouldn't it? (The
following
example does not involve the creation of a zoo object; in reality,
similar
problems are encountered when I create a zoo object)
Univariate zoo series are by default vectors, i.e., have no "dim"
attribute. You can either choose to store a matrix instead of a
vector in
the zoo series - or you can use NCOL() instead of ncol() to extract
the
number of columns. See the corresponding manual pages for more
details. An
illustration is included below:
## univariate series
R> x <- sin(1:4)
R> z <- zoo(x)
R> z
1 2 3 4
0.8414710 0.9092974 0.1411200 -0.7568025
R> dim(z)
NULL
R> ncol(z)
NULL
R> NCOL(z)
[1] 1
## alternatives to create a 1-column matrix instead of a vector
R> z1 <- zoo(matrix(x, ncol = 1))
R> z1
1 0.8414710
2 0.9092974
3 0.1411200
4 -0.7568025
R> dim(z1)
[1] 4 1
R> dim(z) <- c(NROW(z), NCOL(z))
R> z
1 0.8414710
2 0.9092974
3 0.1411200
4 -0.7568025
R> dim(z)
[1] 4 1
temp5<-read.csv("A_**Consumption.csv", header=TRUE)> temp5[1:3,]
TIME
C C_D C_ND
1 196101 70345 1051 69294
2 196102 61738 905 60833
3 196103 63838 860 62978> temp6<-temp5[,2:ncol(temp5)]> temp6[1:3,]
C C_D C_ND
1 70345 1051 69294
2 61738 905 60833
3 63838 860 62978> colnames(temp6)[1] "C" "C_D" "C_ND">
temp7<-read.csv("A_FX_EUR_Q.**csv", header=TRUE)> temp7[1:3,]
TIME
EUR
1 198001 1.41112
2 198002 1.39108
3 198003 1.42323> temp8<-temp7[,2:ncol(temp7)]> temp8[1:3,]Error in
temp8[1:3, ] : incorrect number of dimensions
ncol(temp6)[1] 3> ncol(temp8) # Why isn't it 1?NULL
temp8 [1] 1.411120 1.391080 1.423230 1.342050 1.232870
[6] 1.115090 1.032930 1.089250 1.036320 1.001850
[11] 0.950641 0.933593 0.947940 0.911204 0.860682
[16] 0.843864 0.831666 0.824776 0.768626 0.732064
[21] 0.684473 0.726018 0.784729 0.852911 0.922885
[26] 0.958778 1.012740 1.038160 1.124550 1.149780
[31] 1.128450 1.214120 1.233530 1.216270 1.113620
[36] 1.170250 1.126230 1.074330 1.078480 1.127870
[41] 1.205540 1.222740 1.296500 1.366550 1.341280
[46] 1.187600 1.176790 1.254490 1.262610 1.271820
[51] 1.385930 1.268130 1.190480 1.206840 1.150270
[56] 1.140010 1.125200 1.163450 1.226830 1.240210
[61] 1.273300 1.331010 1.312420 1.317350 1.287330
[66] 1.254500 1.274210 1.261930 1.178970 1.143500
[71] 1.093320 1.123400 1.086770 1.100380 1.117670
[76] 1.176960 1.121600 1.056900 1.048600 1.038000
[81] 0.986500 0.933200 0.905200 0.868300 0.923200
[86] 0.872500 0.890300 0.895900 0.876600 0.918800
[91] 0.983800 0.999400 1.073100 1.137200 1.124800
[96] 1.189000 1.249700 1.204600 1.222000 1.297700
[101] 1.311300 1.259400 1.219900 1.188400 1.202300
[106] 1.258200 1.274300 1.288700 1.310600 1.348100
[111] 1.373800 1.448600 1.497600 1.562200 1.505000
[116] 1.318000 1.302900 1.363200 1.430300 1.477900
[121] 1.382900 1.270800 1.291000 1.358300 1.368000
[126] 1.439100 1.412700 1.348200 1.310800 1.281400
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______________________________________________
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
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Alameda, CA, USA
______________________________________________
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