[R] Question about datatypes/plotting issue
Gabor Grothendieck
ggrothendieck at gmail.com
Wed Mar 11 18:06:01 CET 2009
Another approach is to use yearmon. e.g.
> library(zoo)
> as.yearmon("January 1987", "%B %Y")
[1] "Jan 1987"
Thus we can replace the w <- line in my example code with:
w <- zoo(as.matrix(W[-1]), as.yearmon(W[,1], "%B %Y"))
On Wed, Mar 11, 2009 at 12:48 PM, Oscar Bonilla <obonilla at galileo.edu> wrote:
> David,
>
> I struggled with this for a while. I think the problem with the dates I have
> is that they are not specific dates, they are "partial" dates. A workaround
> for that that I got from someone else in the list was:
>
> as.Date(paste(x$Date, '1'), '%B %Y %d')
>
> to make them specific dates (the first of the month).
>
> Cheers,
>
> -Oscar
>
> On Mar 10, 2009, at 7:58 PM, David Winsemius wrote:
>
>> You need to convert W$Date into a real date variable. At the moment it is
>> just a character variable.
>>
>> > str(W)
>> 'data.frame': 265 obs. of 23 variables:
>> $ Date : Factor w/ 265 levels " ","April 1987",..: 1 90 68 156
>> 2 178 134 ...
>> $ AZ.Phoenix : Factor w/ 236 levels "","100.00","100.43",..: 236 1 1
>> 1 1 1 1 1 1 1 ...
>> $ CA.Los.Angeles : Factor w/ 260 levels "100.00","100.02",..: 260 113 114
>> 115 116 ...
>> $ CA.San.Diego : Factor w/ 261 levels "100.00","101.07",..: 261 109 110
>> 111 112 ...
>> $ CA.San.Francisco: Factor w/ 256 levels "100.00","102.70",..: 256 108 109
>> 110 111 ...
>> .(output trimmed)
>> .
>> .
>> ?Date # not the variable name, the R class name
>> ?format.Date
>> ?strptime
>>
>> Unfortunately I seem to be at one of the many limits to my knowledge:
>> This code behaves in the manner I expected:
>>
>> > format(Sys.time(), "%a %b %d %X %Y %Z")
>> [1] "Tue Mar 10 22:19:28 2009 EDT"
>> > strptime(format(Sys.time(), "%a %b %d %X %Y %Z"), format="%a %b %d %X %Y
>> > %Z")
>> [1] "2009-03-10 22:20:04"
>>
>> Whereas this code does not:
>> > format(Sys.Date(), "%B %Y")
>> [1] "March 2009"
>> > as.Date(format(Sys.Date(), "%B %Y"), "%B %Y")
>> # would have assumed one was the inverse of the other, but ...
>>
>> [1] NA
>>
>> For some reason I cannot get the space delimited Month-YYYY combo to
>> convert. I can getother space delimited formats to work for input or
>> output:
>> > as.Date("03 1998", "%M %Y")
>> [1] "1998-03-10"
>>
>> > format(Sys.Date(), "%B %Y")
>> [1] "March 2009"
>>
>> Puzzled;
>> --
>> David Winsemius
>>
>> On Mar 10, 2009, at 9:15 PM, Oscar Bonilla wrote:
>>
>>> Hi,
>>>
>>> I am trying to plot the Case-Shiller index found at:
>>> http://www2.standardandpoors.com/spf/pdf/index/CSHomePrice_History_022445.xls
>>>
>>> The way I'm importing it into R is as follows:
>>>
>>> library(gdata)
>>> W <-
>>> read.xls("http://www2.standardandpoors.com/spf/pdf/index/CSHomePrice_History_022445.xls",
>>> header=TRUE)
>>> attach(W)
>>>
>>> To give you and idea of what the data looks like:
>>>
>>> > head(W)
>>> Date AZ.Phoenix CA.Los.Angeles CA.San.Diego CA.San.Francisco
>>> 1 PHXR LXXR SDXR SFXR
>>> 2 January 1987 59.33 54.67 46.61
>>> 3 February 1987 59.65 54.89 46.87
>>> 4 March 1987 59.99 55.16 47.32
>>> 5 April 1987 60.81 55.85 47.69
>>> 6 May 1987 61.67 56.35 48.31
>>> CO.Denver DC.Washington FL.Miami FL.Tampa GA.Atlanta IL.Chicago MA.Boston
>>> 1 DNXR WDXR MIXR TPXR ATXR CHXR
>>> BOXR
>>> 2 50.20 64.11 68.50 77.33 53.55
>>> 70.04
>>> 3 49.96 64.77 68.76 77.93 54.64
>>> 70.08
>>> 4 50.15 65.71 69.23 77.76 54.80
>>> 70.00
>>> 5 50.55 66.40 69.20 77.56 54.88
>>> 70.70
>>> 6 50.63 67.27 69.46 77.85 55.43
>>> 71.51
>>> MI.Detroit MN.Minneapolis NC.Charlotte NV.Las.Vegas NY.New.York
>>> OH.Cleveland
>>> 1 DEXR MNXR CRXR LVXR NYXR
>>> CEXR
>>> 2 63.39 66.36 74.42
>>> 53.53
>>> 3 63.94 67.03 75.43
>>> 53.50
>>> 4 64.17 67.34 76.25
>>> 53.68
>>> 5 64.81 67.88 77.34
>>> 53.75
>>> 6 65.18 67.90 79.16
>>> 54.71
>>> OR.Portland TX.Dallas WA.Seattle Composite.10 Composite.20
>>> 1 POXR DAXR SEXR CSXR SPCS20R
>>> 2 41.05 62.82
>>> 3 41.28 63.39
>>> 4 41.06 63.87
>>> 5 40.96 64.57
>>> 6 41.24 65.56
>>>
>>>
>>> Now on to the problem... if I just run
>>>
>>> plot(CA.San.Francisco ~ Date)
>>>
>>> I get:
>>> <pastedGraphic.png>
>>>
>>> Which I suspect is a problem because the Date column is not really a
>>> Date, it is a "factor"
>>>
>>> > class(Date)
>>> [1] "factor"
>>>
>>> If I run:
>>> plot(as.numeric(CA.San.Francisco), type="l")
>>>
>>> I get:
>>>
>>> <pastedGraphic.png>
>>>
>>>
>>> which is wrong, as CA.San.Francisco has no such discontinuity.
>>>
>>> > CA.San.Francisco
>>> [1] SFXR 46.61 46.87 47.32 47.69 48.31 48.83 49.49 49.94 50.69
>>> [11] 51.33 51.80 52.03 52.24 52.64 53.19 54.19 56.09 58.22 58.70
>>> [21] 59.00 59.50 60.37 61.31 62.20 62.66 63.32 64.64 66.27 67.77
>>> [31] 69.26 70.27 71.36 72.31 72.95 73.25 73.02 72.87 72.95 73.50
>>> [41] 74.57 75.12 75.15 74.81 74.45 74.24 73.44 72.58 71.47 71.17
>>> [51] 70.27 69.56 69.46 70.13 70.83 71.39 71.52 71.55 71.21 70.69
>>> [61] 70.05 69.67 69.48 69.17 69.26 69.86 70.02 70.00 69.64 69.51
>>> [71] 69.28 68.85 68.21 67.77 67.44 67.09 67.59 67.90 67.99 67.65
>>> [81] 67.63 67.50 67.18 66.77 66.27 65.98 65.79 66.37 67.05 67.70
>>> [91] 68.15 68.38 68.40 68.21 68.17 68.04 67.93 67.73 67.40 66.79
>>> [101] 67.08 67.31 67.50 67.72 67.78 67.76 67.30 66.80 66.43
>>> 66.15
>>> [111] 65.97 65.92 66.44 67.05 67.67 68.02 68.35 68.43 68.53
>>> 68.72
>>> [121] 68.69 68.80 68.81 69.78 71.09 72.19 73.12 73.75 74.43
>>> 74.76
>>> [131] 75.22 75.31 75.81 76.19 76.53 77.48 79.08 80.82 82.41
>>> 83.52
>>> [141] 84.41 85.06 85.05 84.66 84.50 85.03 85.93 87.51 89.21
>>> 90.82
>>> [151] 92.52 94.20 95.14 96.15 96.72 97.87 98.90 100.00 102.70
>>> 106.56
>>> [161] 110.97 115.01 118.45 119.48 119.95 120.94 123.08 125.66 128.58
>>> 131.16
>>> [171] 133.27 134.10 134.38 134.09 132.64 130.95 129.15 128.60 128.01
>>> 126.99
>>> [181] 125.47 125.13 126.06 128.79 132.62 136.07 139.35 141.02 141.93
>>> 142.29
>>> [191] 142.74 143.06 142.40 141.90 142.19 143.00 144.69 145.53 146.53
>>> 147.75
>>> [201] 148.72 150.25 151.75 153.36 154.62 155.93 158.11 160.90 164.65
>>> 167.76
>>> [211] 171.51 173.85 175.89 178.15 180.75 183.15 185.72 189.35 193.50
>>> 198.30
>>> [221] 201.86 205.52 208.92 211.56 212.86 214.73 215.55 215.70 215.11
>>> 214.78
>>> [231] 215.50 216.04 217.52 218.37 218.12 217.63 217.22 216.37 215.42
>>> 213.84
>>> [241] 212.13 211.78 210.78 211.09 211.47 210.89 209.48 208.64 208.15
>>> 206.46
>>> [251] 202.03 195.49 189.23 183.81 174.54 168.38 164.63 162.70 159.83
>>> 156.88
>>> [261] 151.42 145.53 139.44 135.28 130.12
>>> 256 Levels: 100.00 102.70 106.56 110.97 115.01 118.45 119.48 119.95 ...
>>> SFXR
>>>
>>> However, as.numeric(CA.San.Francisco) does have it!
>>>
>>> > as.numeric(CA.San.Francisco)
>>> [1] 256 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123
>>> 124
>>> [19] 125 126 127 128 129 130 131 132 133 134 140 164 185 199 205 211 214
>>> 217
>>> [37] 215 213 214 219 224 227 228 226 223 221 218 212 207 203 199 190 187
>>> 198
>>> [55] 201 206 208 209 204 200 197 192 188 184 185 194 196 195 191 189 186
>>> 183
>>> [73] 173 164 154 149 156 166 168 158 157 155 150 144 140 138 135 141 147
>>> 160
>>> [91] 171 175 176 173 172 170 167 162 153 145 148 152 155 161 165 163 151
>>> 146
>>> [109] 142 139 137 136 143 147 159 169 174 177 178 180 179 181 182 193 202
>>> 210
>>> [127] 216 220 222 225 229 230 231 232 233 234 235 236 237 238 239 244 243
>>> 241
>>> [145] 240 242 245 246 247 248 249 250 251 252 253 254 255 1 2 3 4
>>> 5
>>> [163] 6 7 8 9 10 13 17 23 26 28 29 27 25 22 20 18 16
>>> 15
>>> [181] 12 11 14 19 24 31 32 34 36 38 40 42 39 35 37 41 43
>>> 44
>>> [199] 45 46 47 48 50 51 52 53 55 57 60 61 63 64 66 67 68
>>> 69
>>> [217] 71 73 74 76 77 79 83 89 92 94 99 100 96 95 98 101 104
>>> 107
>>> [235] 106 105 103 102 97 93 91 90 85 87 88 86 84 82 81 80 78
>>> 75
>>> [253] 72 70 65 62 59 58 56 54 49 44 33 30 21
>>>
>>> What I'd like to get, is a graph like this (the red line):
>>>
>>> <pastedGraphic.png>
>>>
>>> I'm really puzzled about what's going on here. Any help would be greatly
>>> appreciated.
>>>
>>> Thanks,
>>>
>>> -Oscar
>>>
>>> ______________________________________________
>>> R-help at r-project.org mailing list
>>> https://stat.ethz.ch/mailman/listinfo/r-help
>>> PLEASE do read the posting guide
>>> http://www.R-project.org/posting-guide.html
>>> and provide commented, minimal, self-contained, reproducible code.
>>
>> David Winsemius, MD
>> Heritage Laboratories
>> West Hartford, CT
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> 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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