如何提取R中列表的所有元素的最后n个值？
要提取R中列表的所有元素的最后n个值，我们可以按照以下步骤操作-
首先，创建一个列表。
然后，使用tail函数和sapply函数提取列表中所有元素的最后n个值。
示例1
创建列表
让我们创建一个列表，如下所示-
List1<-list(v1=rnorm(50),v2=rnorm(50),v3=rnorm(50),v4=rnorm(50)) List1输出结果
执行时，上述脚本生成以下内容output(thisoutputwillvaryonyoursystemduetorandomization)-
$v1 [1] -0.329223160 -0.345938441 -0.782534244 0.106924619 -0.494456509 [6] 0.758347069 0.015722368 -0.138039612 1.596068610 1.446460755 [11] -0.628530894 -0.218582626 0.008163983 -0.501272224 -1.764751740 [16] 1.710383478 1.169141833 0.557281055 1.262848553 2.024126740 [21] -0.852927602 -1.211188695 -0.441880820 -1.206217921 -0.797646563 [26] -0.967059738 -1.395283571 -0.098682041 0.451534648 0.642313947 [31] -0.932702753 -0.565765092 1.783998547 1.533496141 1.786930703 [36] -0.925787866 1.088374868 1.226852811 -0.261073401 -0.806575473 [41] -0.134762187 -1.128852338 -1.377805948 0.367587618 -0.220392434 [46] -0.016853901 -2.461667388 1.534953135 0.761156418 0.176827166 $v2 [1] -0.76099841 0.86771800 -0.63181854 -0.51631398 -2.53535239 -0.70968787 [7] -1.21191069 -0.96709946 0.96159762 1.81099044 -0.99090458 0.06723956 [13] -0.35698980 0.49001623 -0.11009238 0.55431489 -1.06048023 1.48361978 [19] 0.54117661 -0.54153867 0.77857859 1.29583082 -0.33251194 0.11096752 [25] -1.27335075 0.36533059 -0.17898800 2.22118426 -0.40835479 -0.03293850 [31] 0.92731420 1.73639400 1.00053948 1.61819404 0.42900488 1.89540248 [37] 0.01959906 1.35908615 -0.59017510 -0.37152636 -0.65929794 1.26330276 [43] -1.11545727 -0.51687445 0.39558303 -2.88120088 0.69623946 -0.71496741 [49] -1.42748758 -0.27860230 $v3 [1] -0.24000676 1.06523149 -2.14495028 0.17865037 0.37816840 -0.80573760 [7] 0.90013593 -0.83107406 1.05407018 0.43395124 1.17628814 1.29173112 [13] -0.56485152 -2.80729650 0.78636837 -0.37919322 -0.09312585 1.46810227 [19] 1.43798664 0.92268563 0.10122861 0.58440289 -1.62562346 1.10598635 [25] 0.60992245 0.70294428 0.92639712 -0.10686199 -0.58975841 -0.68471500 [31] -0.58895744 -0.35081472 0.23719477 -0.16315963 -0.61086616 0.40839189 [37] -0.05746384 -1.57600113 2.37700458 0.91087399 -1.31715348 0.32757144 [43] -1.14353590 0.07380687 -0.92749195 -0.99620201 0.34564712 -1.04244193 [49] -0.19390489 0.33184937 $v4 [1] -1.56940261 0.91242445 1.06215295 0.24439339 -0.18742524 0.17557542 [7] 1.64408674 -0.25826879 0.55959326 -0.33062472 -0.36383674 0.41828547 [13] -0.19863830 0.77664560 -1.32160811 -1.75454687 0.73355965 -0.19907927 [19] 0.98342758 0.21656616 0.22308005 0.17787506 0.54880953 -0.44581818 [25] 0.77578620 3.00871099 1.38691178 0.45234333 -0.70813049 -0.22781098 [31] -0.57699962 1.05857575 0.82046234 0.16887100 1.27772419 0.96839414 [37] -0.12340026 0.24655061 -1.75160008 -2.61150272 -1.39167654 0.07710894 [43] 0.54528189 -0.10825879 -1.47898170 -0.53123971 -0.81399129 -0.23731978 [49] 0.23258015 -0.79579865
提取列表中所有元素的最后n个值
使用带有sapply函数的tail函数提取List1中所有元素的最后10个值-
List1<-list(v1=rnorm(50),v2=rnorm(50),v3=rnorm(50),v4=rnorm(50)) sapply(List1,tail,10)输出结果
v1 v2 v3 v4 [1,] -0.1347622 -0.6592979 -1.31715348 -1.39167654 [2,] -1.1288523 1.2633028 0.32757144 0.07710894 [3,] -1.3778059 -1.1154573 -1.14353590 0.54528189 [4,] 0.3675876 -0.5168744 0.07380687 -0.10825879 [5,] -0.2203924 0.3955830 -0.92749195 -1.47898170 [6,] -0.0168539 -2.8812009 -0.99620201 -0.53123971 [7,] -2.4616674 0.6962395 0.34564712 -0.81399129 [8,] 1.5349531 -0.7149674 -1.04244193 -0.23731978 [9,] 0.7611564 -1.4274876 -0.19390489 0.23258015 [10,] 0.1768272 -0.2786023 0.33184937 -0.79579865
示例2
创建列表
让我们创建一个列表，如下所示-
List2<-list(x=rpois(200,5),y=rpois(200,2),z=rpois(200,10)) List2输出结果
执行时，上述脚本生成以下内容output(thisoutputwillvaryonyoursystemduetorandomization)-
$x [1] 6 4 2 2 5 11 3 8 9 3 4 7 4 4 4 10 5 3 5 4 3 9 2 6 3 [26] 7 5 4 5 8 3 4 6 6 5 11 1 2 6 7 5 8 5 6 3 4 6 3 5 1 [51] 8 1 6 4 2 5 8 7 5 5 5 6 4 7 1 4 4 4 0 6 6 5 6 6 1 [76] 3 5 9 4 5 1 7 5 4 10 8 4 5 4 4 3 6 3 4 7 8 2 3 4 4 [101] 1 12 4 7 4 7 5 5 5 4 8 5 5 2 8 7 4 2 5 5 3 4 6 6 5 [126] 9 4 4 6 5 4 5 6 5 4 4 9 5 6 4 5 7 4 4 5 6 4 3 4 0 [151] 6 4 7 7 5 2 6 7 3 4 7 8 5 9 4 5 2 8 5 4 3 3 4 4 12 [176] 8 2 4 4 5 3 13 2 2 6 2 7 2 4 6 2 10 4 6 5 2 2 4 8 4 $y [1] 1 1 2 2 2 2 2 2 2 2 1 3 0 4 3 4 3 2 1 2 3 3 2 2 2 4 2 2 4 2 2 1 2 5 2 1 3 [38] 1 0 2 1 3 4 2 0 1 3 2 3 4 3 3 3 5 0 1 2 2 5 5 1 2 3 2 2 3 1 5 1 4 0 5 1 0 [75] 2 1 2 1 1 2 1 2 0 4 1 2 0 4 4 6 0 8 2 5 0 2 2 1 3 4 2 2 0 1 1 1 1 3 4 3 5 [112] 3 1 4 1 3 0 1 1 4 4 1 1 3 1 1 4 0 0 5 1 0 2 1 2 2 2 2 1 0 0 0 5 0 2 2 5 1 [149] 0 2 3 4 4 1 2 3 1 3 1 1 1 3 1 1 0 0 1 2 2 1 1 1 4 2 1 1 1 1 2 1 2 3 2 3 2 [186] 2 1 2 3 2 2 1 3 3 3 1 3 0 1 3 $z [1] 15 12 15 18 8 6 12 8 17 10 8 11 9 9 11 3 11 2 6 13 6 18 15 8 11 [26] 11 8 12 7 14 14 10 13 10 14 11 8 14 7 16 5 13 14 9 10 11 8 12 9 11 [51] 4 7 10 7 8 7 14 10 8 11 3 7 6 3 7 12 9 9 8 8 12 8 10 11 6 [76] 11 10 15 9 9 8 7 17 10 11 12 9 5 16 9 9 9 7 6 9 11 12 6 12 9 [101] 11 6 7 9 10 7 8 14 15 5 13 12 9 10 16 9 10 12 9 13 9 9 7 15 7 [126] 14 10 5 11 5 10 13 8 6 11 10 7 13 11 15 12 7 10 8 6 6 8 6 10 9 [151] 8 10 16 11 7 10 13 10 9 11 14 11 8 9 6 9 12 6 10 11 9 13 12 12 10 [176] 11 10 13 9 11 2 9 8 7 8 11 6 7 7 16 14 13 18 7 19 5 9 9 8 13
提取列表中所有元素的最后n个值
使用带有sapply函数的tail函数提取List2中所有元素的最后10个值-
List2<-list(x=rpois(200,5),y=rpois(200,2),z=rpois(200,10)) sapply(List2,tail,10)输出结果
x y z [1,] 2 2 14 [2,] 10 1 13 [3,] 4 3 18 [4,] 6 3 7 [5,] 5 3 19 [6,] 2 1 5 [7,] 2 3 9 [8,] 4 0 9 [9,] 8 1 8 [10,] 4 3 13