A pre-loaded example dataset in R

Main page: https://www.rdocumentation.org/packages/datasets/versions/3.6.2/topics/sunspot.month

head(sunspot.month)
## [1] 58.0 62.6 70.0 55.7 85.0 83.5
require(stats); require(graphics)
## Compare the monthly series
plot (sunspot.month,
      main="sunspot.month & sunspots [package'datasets']", col=2)
lines(sunspots) # -> faint differences where they overlap

## Now look at the difference :
all(tsp(sunspots)     [c(1,3)] ==
    tsp(sunspot.month)[c(1,3)]) ## Start & Periodicity are the same
## [1] TRUE
n1 <- length(sunspots)
table(eq <- sunspots == sunspot.month[1:n1]) #>  132  are different !
## 
## FALSE  TRUE 
##   143  2677
i <- which(!eq)
rug(time(eq)[i])

s1 <- sunspots[i] ; s2 <- sunspot.month[i]
cbind(i = i, time = time(sunspots)[i], sunspots = s1, ss.month = s2,
      perc.diff = round(100*2*abs(s1-s2)/(s1+s2), 1))
##           i     time sunspots ss.month perc.diff
##   [1,]   55 1753.500     22.2     22.0       0.9
##   [2,]  838 1818.750     31.7     31.6       0.3
##   [3,]  841 1819.000     32.5     32.8       0.9
##   [4,]  862 1820.750      9.0      8.9       1.1
##   [5,]  864 1820.917      9.7      9.1       6.4
##   [6,]  866 1821.083      4.3      4.2       2.4
##   [7,]  876 1821.917      0.0      0.2     200.0
##   [8,]  901 1824.000     21.6     21.7       0.5
##   [9,]  917 1825.333     15.4     15.5       0.6
##  [10,]  920 1825.583     25.4     25.7       1.2
##  [11,]  943 1827.500     42.9     42.3       1.4
##  [12,]  946 1827.750     57.2     56.1       1.9
##  [13,]  955 1828.500     54.3     54.2       0.2
##  [14,]  960 1828.917     46.6     46.9       0.6
##  [15,]  965 1829.333     67.5     67.4       0.1
##  [16,]  968 1829.583     78.3     77.6       0.9
##  [17,]  976 1830.250    107.1    106.3       0.7
##  [18,]  988 1831.250     54.6     54.5       0.2
##  [19,]  992 1831.583     54.9     55.0       0.2
##  [20,]  994 1831.750     46.2     46.3       0.2
##  [21,]  998 1832.083     55.5     55.6       0.2
##  [22,] 1003 1832.500     13.9     14.0       0.7
##  [23,] 1047 1836.167     98.1     98.2       0.1
##  [24,] 1061 1837.333    111.3    111.7       0.4
##  [25,] 1081 1839.000    107.6    105.6       1.9
##  [26,] 1087 1839.500     84.7     84.8       0.1
##  [27,] 1090 1839.750     90.8     90.9       0.1
##  [28,] 1092 1839.917     63.6     63.7       0.2
##  [29,] 1095 1840.167     55.5     67.8      20.0
##  [30,] 1102 1840.750     49.8     55.0       9.9
##  [31,] 1105 1841.000     24.0     24.1       0.4
##  [32,] 1108 1841.250     42.6     40.2       5.8
##  [33,] 1109 1841.333     67.4     67.5       0.1
##  [34,] 1113 1841.667     35.1     36.5       3.9
##  [35,] 1124 1842.583     26.5     26.6       0.4
##  [36,] 1125 1842.667     18.5     18.4       0.5
##  [37,] 1132 1843.250      8.8      9.5       7.7
##  [38,] 1145 1844.333     12.0     11.6       3.4
##  [39,] 1149 1844.667      6.9      7.0       1.4
##  [40,] 1156 1845.250     56.9     57.0       0.2
##  [41,] 1168 1846.250     69.2     69.3       0.1
##  [42,] 1185 1847.667    161.2    160.9       0.2
##  [43,] 1191 1848.167    108.9    108.6       0.3
##  [44,] 1194 1848.417    123.8    129.0       4.1
##  [45,] 1196 1848.583    132.5    132.6       0.1
##  [46,] 1200 1848.917    159.9    159.5       0.3
##  [47,] 1201 1849.000    156.7    157.0       0.2
##  [48,] 1202 1849.083    131.7    131.8       0.1
##  [49,] 1203 1849.167     96.5     96.2       0.3
##  [50,] 1206 1849.417     81.2     81.1       0.1
##  [51,] 1208 1849.583     61.3     67.7       9.9
##  [52,] 1211 1849.833     99.7     99.0       0.7
##  [53,] 1224 1850.917     60.0     61.0       1.7
##  [54,] 1235 1851.833     50.9     51.0       0.2
##  [55,] 1238 1852.083     67.5     66.4       1.6
##  [56,] 1243 1852.500     42.0     42.1       0.2
##  [57,] 1256 1853.583     50.4     50.5       0.2
##  [58,] 1258 1853.750     42.3     42.4       0.2
##  [59,] 1264 1854.250     26.4     26.5       0.4
##  [60,] 1270 1854.750     12.7     12.6       0.8
##  [61,] 1272 1854.917     21.4     21.6       0.9
##  [62,] 1282 1855.750      9.7      9.6       1.0
##  [63,] 1283 1855.833      4.3      4.2       2.4
##  [64,] 1290 1856.417      5.0      5.2       3.9
##  [65,] 1301 1857.333     29.2     28.5       2.4
##  [66,] 1333 1860.000     81.5     82.4       1.1
##  [67,] 1334 1860.083     88.0     88.3       0.3
##  [68,] 1346 1861.083     77.8     77.7       0.1
##  [69,] 1350 1861.417     87.8     88.1       0.3
##  [70,] 1366 1862.750     42.0     41.9       0.2
##  [71,] 1407 1866.167     24.6     24.5       0.4
##  [72,] 1424 1867.583      4.9      4.8       2.1
##  [73,] 1427 1867.833      9.3      9.6       3.2
##  [74,] 1429 1868.000     15.6     15.5       0.6
##  [75,] 1430 1868.083     15.8     15.7       0.6
##  [76,] 1435 1868.500     28.6     29.0       1.4
##  [77,] 1437 1868.667     43.8     47.2       7.5
##  [78,] 1438 1868.750     61.7     61.6       0.2
##  [79,] 1442 1869.083     59.3     59.9       1.0
##  [80,] 1445 1869.333    104.0    103.9       0.1
##  [81,] 1450 1869.750     59.4     59.3       0.2
##  [82,] 1451 1869.833     77.4     78.1       0.9
##  [83,] 1452 1869.917    104.3    104.4       0.1
##  [84,] 1455 1870.167    159.4    157.5       1.2
##  [85,] 1472 1871.583    110.0    110.1       0.1
##  [86,] 1476 1871.917     90.3     90.4       0.1
##  [87,] 1486 1872.750    103.5    102.6       0.9
##  [88,] 1497 1873.667     47.5     47.1       0.8
##  [89,] 1498 1873.750     47.4     47.1       0.6
##  [90,] 1514 1875.083     22.2     21.5       3.2
##  [91,] 1527 1876.167     31.2     30.6       1.9
##  [92,] 1539 1877.167     11.7     11.9       1.7
##  [93,] 1541 1877.333     21.2     21.6       1.9
##  [94,] 1542 1877.417     13.4     14.2       5.8
##  [95,] 1543 1877.500      5.9      6.0       1.7
##  [96,] 1545 1877.667     16.4     16.9       3.0
##  [97,] 1547 1877.833     14.5     14.2       2.1
##  [98,] 1548 1877.917      2.3      2.2       4.4
##  [99,] 1550 1878.083      6.0      6.6       9.5
## [100,] 1553 1878.333      5.8      5.9       1.7
## [101,] 1561 1879.000      0.8      1.0      22.2
## [102,] 1571 1879.833     12.9     13.1       1.5
## [103,] 1572 1879.917      7.2      7.3       1.4
## [104,] 1574 1880.083     27.5     27.2       1.1
## [105,] 1575 1880.167     19.5     19.3       1.0
## [106,] 1576 1880.250     19.3     19.5       1.0
## [107,] 1588 1881.250     51.7     51.6       0.2
## [108,] 1592 1881.583     58.0     58.4       0.7
## [109,] 1594 1881.750     64.0     64.4       0.6
## [110,] 1598 1882.083     69.3     69.5       0.3
## [111,] 1599 1882.167     67.5     66.8       1.0
## [112,] 1613 1883.333     32.1     31.5       1.9
## [113,] 1614 1883.417     76.5     76.3       0.3
## [114,] 1623 1884.167     86.8     87.5       0.8
## [115,] 1643 1885.833     33.3     30.9       7.5
## [116,] 1656 1886.917     12.4     13.0       4.7
## [117,] 1663 1887.500     23.3     23.4       0.4
## [118,] 1683 1889.167      7.0      6.7       4.4
## [119,] 1687 1889.500      9.7      9.4       3.1
## [120,] 1712 1891.583     33.2     33.0       0.6
## [121,] 1716 1891.917     32.3     32.5       0.6
## [122,] 1723 1892.500     76.8     76.5       0.4
## [123,] 1734 1893.417     88.2     89.9       1.9
## [124,] 1735 1893.500     88.8     88.6       0.2
## [125,] 1738 1893.750     79.7     80.0       0.4
## [126,] 1774 1896.750     28.4     28.7       1.1
## [127,] 1837 1902.000      5.2      5.5       5.6
## [128,] 2126 1926.083     70.0     69.9       0.1
## [129,] 2151 1928.167     85.4     85.5       0.1
## [130,] 2153 1928.333     76.9     77.0       0.1
## [131,] 2162 1929.083     64.1     62.8       2.0
## [132,] 2174 1930.083     49.2     49.9       1.4
## [133,] 2233 1935.000     18.9     18.6       1.6
## [134,] 2315 1941.833     38.3     38.4       0.3
## [135,] 2329 1943.000     12.4     12.5       0.8
## [136,] 2378 1947.083    113.4    133.4      16.2
## [137,] 2427 1951.167     59.9     55.9       6.9
## [138,] 2498 1957.083    130.2    130.3       0.1
## [139,] 2552 1961.583     55.9     55.8       0.2
## [140,] 2556 1961.917     40.0     39.9       0.3
## [141,] 2594 1965.083     14.2     14.3       0.7
## [142,] 2790 1981.417     90.0     90.9       1.0
## [143,] 2819 1983.833     33.3     33.4       0.3
## How to recreate the "old" sunspot.month (R <= 3.0.3):
.sunspot.diff <- cbind(
    i = c(1202L, 1256L, 1258L, 1301L, 1407L, 1429L, 1452L, 1455L,
          1663L, 2151L, 2329L, 2498L, 2594L, 2694L, 2819L),
    res10 = c(1L, 1L, 1L, -1L, -1L, -1L, 1L, -1L,
          1L, 1L, 1L, 1L, 1L, 20L, 1L))
ssm0 <- sunspot.month[1:2988]
with(as.data.frame(.sunspot.diff), ssm0[i] <<- ssm0[i] - res10/10)
sunspot.month.0 <- ts(ssm0, start = 1749, frequency = 12)