Removing one value from ts() object in R without changing the class of the object

Question

I have a dataset, which has ts() class.

The dput looks like this:

structure(c(0.0499999999999998, -0.0499999999999998, 0.12, 0.28, 
0.109999999999999, 0.0500000000000007, -0.44, 0.16, -0.11, -0.8, 
-0.24, 0.0800000000000001, -0.13, -0.19, 0.0500000000000007, 
0.56, -0.2, -0.0299999999999994, -0.130000000000001, -0.109999999999999, 
-0.0700000000000003, 0.0499999999999998, 0.100000000000001, -0.04, 
-0.0200000000000005, 0.13, -0.21, -0.149999999999999, -0.180000000000001, 
-0.13, -0.0800000000000001, -0.13, 0.0800000000000001, 0.41, 
0.0499999999999998, 0.19, -0.11, 0, -0.2, -0.13, 0.0300000000000002, 
-0.27, -0.159999999999999, -0.04, -0.0800000000000001, -0.0300000000000002, 
-0.04, -0.0299999999999998, 0.0600000000000001, -0.04, -0.11, 
-0.13, -0.12, 0.0500000000000003, -0.1, -0.12, -0.0299999999999998, 
-0.0100000000000002, 0.0700000000000003, 0.12, 0.0300000000000002, 
-0.11, 0.0899999999999999, 0.53, 0.3, 0.0899999999999999, 0.0300000000000002, 
-0.3, 0.0699999999999994, 0.2, -0.0300000000000002, -0.13, 0.04, 
0, -0.149999999999999, -0.0300000000000002, -0.0300000000000002, 
-0.00999999999999979, 0.04, -0.12, -0.04, -0.14, -0.19, 0.04, 
0.0600000000000001, -0.1, 0.17, 0.14, 0.0699999999999998, -0.14, 
-0.02, -0.0900000000000003, 0.14, 0.02, -0.0899999999999999, 
-0.21, 0.0299999999999998, -0.0899999999999999, 0, -0.0300000000000002, 
-0.13, 0, 0.02, 0.0100000000000002, 0.3, 0.43, -0.0499999999999998, 
0.0199999999999996, 0.0300000000000002, -0.16, -0.0300000000000002, 
-0.11, 0.0700000000000003, -0.0900000000000003, -0.0800000000000001, 
0.1, 0.02, 0.0300000000000002, 0.0800000000000001, 0.3, 0.11, 
0.0299999999999994, 0.12, -0.0199999999999996, -0.04, 0.0199999999999996, 
0.0800000000000001, 0.2, 0.04, -0.23, -0.18, -0.0899999999999999, 
-0.11, -0.12, -0.0699999999999994, -0.27, -0.0299999999999998, 
-0.15, -0.02, 0.0899999999999999, 0.0100000000000002, 0.02, -0.1, 
-0.15, -0.02, -0.14, -0.0800000000000001, -0.0699999999999998, 
-0.14, -0.0800000000000001), .Tsp = c(2008.16666666667, 2020.58333333333, 
12), class = "ts")

Visually it looks like:

I am trying to remove one value for March 2008. But it I use something

foo[-c(1:1)]

it converts data into numeric and it will not work for me.

How to remove this variable and keep the ts() class and date values? Thanks!

Answer 1

Any of these should give the requested result.

The first uses window.ts to start at the indicated year and month.

The second also uses window.ts but specifies it in terms of the second time value rather than hard coding it.

The third replaces the first value with NA and then runs na.omit to remove it. It should work if the series has no NA values.

The fourth adds the series to a zero series which is lagged forward and should work if the series has no NA values.

The fifth converts to zoo class where subscripting works and then converts back.

The sixth is the same as the second except it uses a different expression for the second time point.

window(foo, start = c(2008, 4))

window(foo, start = time(foo)[2])

na.omit(replace(foo, 1, NA))

foo + lag(0 * foo, -1)

library(zoo)
as.ts(as.zoo(foo)[-1])

window(foo, start = tsp(foo)[1] + deltat(foo))

Answer 2

An option is to reconvert back to ts

foo2 <- ts(foo[-1], start = index(foo)[2], frequency = frequency(foo))

-output

foo2
#       Jan   Feb   Mar   Apr   May   Jun   Jul   Aug   Sep   Oct   Nov   Dec
#2008                   -0.05  0.12  0.28  0.11  0.05 -0.44  0.16 -0.11 -0.80
#2009 -0.24  0.08 -0.13 -0.19  0.05  0.56 -0.20 -0.03 -0.13 -0.11 -0.07  0.05
#2010  0.10 -0.04 -0.02  0.13 -0.21 -0.15 -0.18 -0.13 -0.08 -0.13  0.08  0.41
#2011  0.05  0.19 -0.11  0.00 -0.20 -0.13  0.03 -0.27 -0.16 -0.04 -0.08 -0.03
#2012 -0.04 -0.03  0.06 -0.04 -0.11 -0.13 -0.12  0.05 -0.10 -0.12 -0.03 -0.01
#2013  0.07  0.12  0.03 -0.11  0.09  0.53  0.30  0.09  0.03 -0.30  0.07  0.20
#2014 -0.03 -0.13  0.04  0.00 -0.15 -0.03 -0.03 -0.01  0.04 -0.12 -0.04 -0.14
#2015 -0.19  0.04  0.06 -0.10  0.17  0.14  0.07 -0.14 -0.02 -0.09  0.14  0.02
#2016 -0.09 -0.21  0.03 -0.09  0.00 -0.03 -0.13  0.00  0.02  0.01  0.30  0.43
#2017 -0.05  0.02  0.03 -0.16 -0.03 -0.11  0.07 -0.09 -0.08  0.10  0.02  0.03
#2018  0.08  0.30  0.11  0.03  0.12 -0.02 -0.04  0.02  0.08  0.20  0.04 -0.23
#2019 -0.18 -0.09 -0.11 -0.12 -0.07 -0.27 -0.03 -0.15 -0.02  0.09  0.01  0.02
#2020 -0.10 -0.15 -0.02 -0.14 -0.08 -0.07 -0.14 -0.08     

---

or we assign the value to NA

foo[1] <- NA