Question

which（）函数返回给定条件的行索引。是否有类似于哪个（）可以识别给定条件的列索引？或者，有没有其他方法可以获得它？

假设我们有以下数据框。 5个不同城市的小时温度，其中城市名称是列，小时（00到23）是行。如何找出哪个城市记录了最高温度，以及何时记录？

Answer 1

使用这样的样本数据（最多24个）：

    Mobile   Juneau  Phoenix Little Rock Los Angeles
1 9.161109 6.561874 7.900787    3.863214   7.2799115
2 5.597790 3.267891 3.895087    7.589563   0.5756907
3 6.279322 3.578783 5.273761    8.076495   6.2456569
4 3.895283 4.321506 2.665034    2.755444   9.8913468
5 5.889698 5.690749 8.879107    8.233134   3.2684326
6 7.811671 2.033278 1.528914    7.719961   1.3486213

在调用arr.ind=TRUE时使用which给出行和列（此处只有一个）：

> which(df==max(df),arr.ind=TRUE)
     row col
[1,]  14   5

接下来，使用rownames和colnames，您应该能够获得城市名称和小时（有关详细信息，请参阅?which）。

测试数据：

df <- structure(list(Mobile = c(9.16110935388133, 5.59779000002891, 
6.27932160394266, 3.89528321102262, 5.88969846023247, 7.81167097389698, 
1.83368496363983, 4.47858408326283, 5.93715427909046, 3.50760932080448, 
9.44435691693798, 6.31296712905169, 5.32727922545746, 7.65801254892722, 
8.5059278132394, 4.28985294653103, 2.05249830847606, 7.6365390396677, 
9.77846014779061, 8.94446840044111, 0.083497145678848, 7.10133319022134, 
0.554085657931864, 3.60153668094426), Juneau = c(6.56187414424494, 
3.26789108337834, 3.57878275448456, 4.32150553911924, 5.69074853556231, 
2.033277512528, 7.18786624493077, 6.14864403847605, 8.68574564578012, 
1.30817822180688, 1.01500122342259, 8.8916674698703, 5.60441857203841, 
8.86488395975903, 6.64872422581539, 0.683707664720714, 0.72935079690069, 
6.96065725525841, 1.50260855443776, 9.30632123956457, 8.09938014484942, 
3.17607591627166, 1.66992667596787, 6.5417457325384), Phoenix = c(7.90078683523461, 
3.89508724678308, 5.27376119513065, 2.66503410181031, 8.87910738587379, 
1.52891436824575, 1.83640674687922, 7.62884735595435, 1.86433888971806, 
6.2539599230513, 0.442896636668593, 8.08971904451028, 3.22157387156039, 
1.07892997562885, 5.32610179157928, 5.71723570115864, 8.49908272270113, 
9.22176177380607, 5.49865348497406, 2.0716791623272, 2.75534275220707, 
9.54129027202725, 0.547004980035126, 0.0254918588325381), `Little Rock` = c(3.86321445228532, 
7.58956262841821, 8.0764949019067, 2.75544387986884, 8.23313429951668, 
7.71996134659275, 6.78180204005912, 2.48242149595171, 5.22057399619371, 
8.16672697663307, 2.18510434962809, 8.52984978584573, 4.81410115258768, 
9.26382135832682, 5.73062423849478, 4.68517286004499, 4.98139521572739, 
2.03285798197612, 1.81552906520665, 1.28075355896726, 7.3631735984236, 
9.16532466653734, 3.6388257634826, 6.7194988601841), `Los Angeles` = c(7.27991148363799, 
0.575690739788115, 6.24565688893199, 9.89134680945426, 3.26843255432323, 
1.34862127713859, 0.358565023634583, 9.37912961700931, 1.25442329328507, 
1.73299844376743, 9.95316742919385, 7.42675306508318, 6.60283848410472, 
9.98386316467077, 5.81940121715888, 2.53246366977692, 4.47731937048957, 
0.9123918088153, 7.94102079933509, 7.45049795368686, 1.02275986224413, 
2.63348019681871, 1.82409069268033, 7.71245903801173)), row.names = c(NA, 
-24L), class = "data.frame", .Names = c("Mobile", "Juneau", "Phoenix", 
"Little Rock", "Los Angeles"))

等效于（）函数来获取R中的列索引

1 个答案: