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| The str() Function | ||
| ================== | ||
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| Compactly display the internal structure of an R object. | ||
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| * A diagnostic function and an alternative to 'summary' | ||
| * It is especially ell suited to compactly display the ( abbreviated) contents of (possibly nested) lists | ||
| * Roughly one line per basic object | ||
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| str() answers the question: what's in an object? | ||
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| Functions | ||
| --------- | ||
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| > str(str) | ||
| function (object, ...) | ||
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| > str(lm) | ||
| function (formula, data, subset, weights, na.action, method = "qr", model = TRUE, | ||
| x = FALSE, y = FALSE, qr = TRUE, singular.ok = TRUE, contrasts = NULL, | ||
| offset, ...) | ||
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| > str(ls) | ||
| function (name, pos = -1L, envir = as.environment(pos), all.names = FALSE, | ||
| pattern) | ||
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| Vectors | ||
| ------- | ||
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| > x <-rnorm(100, 2, 4) | ||
| > summary(x) | ||
| Min. 1st Qu. Median Mean 3rd Qu. Max. | ||
| -8.647 -0.632 1.874 2.215 4.839 13.450 | ||
| > str(x) | ||
| num [1:100] 0.9986 -6.5211 3.4636 0.5328 0.0474 ... | ||
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| Factors | ||
| ------- | ||
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| > f <-gl(40, 10) | ||
| > str(f) | ||
| Factor w/ 40 levels "1","2","3","4",..: 1 1 1 1 1 1 1 1 1 1 ... | ||
| > summary(f) | ||
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 | ||
| 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 | ||
| 27 28 29 30 31 32 33 34 35 36 37 38 39 40 | ||
| 10 10 10 10 10 10 10 10 10 10 10 10 10 10 | ||
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| Data Frames | ||
| ----------- | ||
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| > library(datasets) | ||
| > head(airquality) | ||
| Ozone Solar.R Wind Temp Month Day | ||
| 1 41 190 7.4 67 5 1 | ||
| 2 36 118 8.0 72 5 2 | ||
| 3 12 149 12.6 74 5 3 | ||
| 4 18 313 11.5 62 5 4 | ||
| 5 NA NA 14.3 56 5 5 | ||
| 6 28 NA 14.9 66 5 6 | ||
| > str(airquality) | ||
| 'data.frame': 153 obs. of 6 variables: | ||
| $ Ozone : int 41 36 12 18 NA 28 23 19 8 NA ... | ||
| $ Solar.R: int 190 118 149 313 NA NA 299 99 19 194 ... | ||
| $ Wind : num 7.4 8 12.6 11.5 14.3 14.9 8.6 13.8 20.1 8.6 ... | ||
| $ Temp : int 67 72 74 62 56 66 65 59 61 69 ... | ||
| $ Month : int 5 5 5 5 5 5 5 5 5 5 ... | ||
| $ Day : int 1 2 3 4 5 6 7 8 9 10 ... | ||
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| Matrix | ||
| ------ | ||
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| > m <- matrix(rnorm(100), 10, 10) | ||
| > str(m) | ||
| num [1:10, 1:10] 1.201 0.712 -0.118 -0.581 -0.467 ... | ||
| > m[, 1] | ||
| [1] 1.2012138 0.7118305 -0.1178031 -0.5812110 -0.4673343 -0.5950841 | ||
| [7] 0.4184978 1.8155424 -1.6733037 -0.7371094 | ||
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| Lists | ||
| ----- | ||
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| > s <- split(airquality, airquality$Month) | ||
| > str(s) | ||
| List of 5 | ||
| $ 5:'data.frame': 31 obs. of 6 variables: | ||
| ..$ Ozone : int [1:31] 41 36 12 18 NA 28 23 19 8 NA ... | ||
| ..$ Solar.R: int [1:31] 190 118 149 313 NA NA 299 99 19 194 ... | ||
| ..$ Wind : num [1:31] 7.4 8 12.6 11.5 14.3 14.9 8.6 13.8 20.1 8.6 ... | ||
| ..$ Temp : int [1:31] 67 72 74 62 56 66 65 59 61 69 ... | ||
| ..$ Month : int [1:31] 5 5 5 5 5 5 5 5 5 5 ... | ||
| ..$ Day : int [1:31] 1 2 3 4 5 6 7 8 9 10 ... | ||
| $ 6:'data.frame': 30 obs. of 6 variables: | ||
| ..$ Ozone : int [1:30] NA NA NA NA NA NA 29 NA 71 39 ... | ||
| ..$ Solar.R: int [1:30] 286 287 242 186 220 264 127 273 291 323 ... | ||
| ..$ Wind : num [1:30] 8.6 9.7 16.1 9.2 8.6 14.3 9.7 6.9 13.8 11.5 ... | ||
| ..$ Temp : int [1:30] 78 74 67 84 85 79 82 87 90 87 ... | ||
| ..$ Month : int [1:30] 6 6 6 6 6 6 6 6 6 6 ... | ||
| ..$ Day : int [1:30] 1 2 3 4 5 6 7 8 9 10 ... | ||
| $ 7:'data.frame': 31 obs. of 6 variables: | ||
| ..$ Ozone : int [1:31] 135 49 32 NA 64 40 77 97 97 85 ... | ||
| ..$ Solar.R: int [1:31] 269 248 236 101 175 314 276 267 272 175 ... | ||
| ..$ Wind : num [1:31] 4.1 9.2 9.2 10.9 4.6 10.9 5.1 6.3 5.7 7.4 ... | ||
| ..$ Temp : int [1:31] 84 85 81 84 83 83 88 92 92 89 ... | ||
| ..$ Month : int [1:31] 7 7 7 7 7 7 7 7 7 7 ... | ||
| ..$ Day : int [1:31] 1 2 3 4 5 6 7 8 9 10 ... | ||
| $ 8:'data.frame': 31 obs. of 6 variables: | ||
| ..$ Ozone : int [1:31] 39 9 16 78 35 66 122 89 110 NA ... | ||
| ..$ Solar.R: int [1:31] 83 24 77 NA NA NA 255 229 207 222 ... | ||
| ..$ Wind : num [1:31] 6.9 13.8 7.4 6.9 7.4 4.6 4 10.3 8 8.6 ... | ||
| ..$ Temp : int [1:31] 81 81 82 86 85 87 89 90 90 92 ... | ||
| ..$ Month : int [1:31] 8 8 8 8 8 8 8 8 8 8 ... | ||
| ..$ Day : int [1:31] 1 2 3 4 5 6 7 8 9 10 ... | ||
| $ 9:'data.frame': 30 obs. of 6 variables: | ||
| ..$ Ozone : int [1:30] 96 78 73 91 47 32 20 23 21 24 ... | ||
| ..$ Solar.R: int [1:30] 167 197 183 189 95 92 252 220 230 259 ... | ||
| ..$ Wind : num [1:30] 6.9 5.1 2.8 4.6 7.4 15.5 10.9 10.3 10.9 9.7 ... | ||
| ..$ Temp : int [1:30] 91 92 93 93 87 84 80 78 75 73 ... | ||
| ..$ Month : int [1:30] 9 9 9 9 9 9 9 9 9 9 ... | ||
| ..$ Day : int [1:30] 1 2 3 4 5 6 7 8 9 10 ... |