How can I subset a list in r by extracting the elements that contain a string?

Question

I have a list:

mylist<-list()
data<-1:162
listlabel<-c("a","bpt","b","fpt")
for (i in 1:4){
label<-listlabel[i]
mylist[[label]]<-data
}

I want to create a new list from the elements in my list that contain a certain string: in this case 'pt'. My new list should contain the elements 'bpt' and 'fpt'.

I thought 'grep' would do it, but when I try it, it returns an empty list.

newlist<-list(grep("pt",mylist))

How can I create the new list keeping only the selected elements containing my string?

Answer 1

grep应该在names上，而不是在list的值上

mylist_sub <- mylist[grep('pt', names(mylist))]

Answer 2

We can use purrr::keep and grepl

library(purrr)
`
mylist %>% keep(grepl('pt', names(mylist)))

output

$bpt
  [1]   1   2   3   4   5   6   7   8   9  10  11  12  13  14  15  16  17  18  19  20  21  22  23
 [24]  24  25  26  27  28  29  30  31  32  33  34  35  36  37  38  39  40  41  42  43  44  45  46
 [47]  47  48  49  50  51  52  53  54  55  56  57  58  59  60  61  62  63  64  65  66  67  68  69
 [70]  70  71  72  73  74  75  76  77  78  79  80  81  82  83  84  85  86  87  88  89  90  91  92
 [93]  93  94  95  96  97  98  99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115
[116] 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138
[139] 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161
[162] 162

$fpt
  [1]   1   2   3   4   5   6   7   8   9  10  11  12  13  14  15  16  17  18  19  20  21  22  23
 [24]  24  25  26  27  28  29  30  31  32  33  34  35  36  37  38  39  40  41  42  43  44  45  46
 [47]  47  48  49  50  51  52  53  54  55  56  57  58  59  60  61  62  63  64  65  66  67  68  69
 [70]  70  71  72  73  74  75  76  77  78  79  80  81  82  83  84  85  86  87  88  89  90  91  92
 [93]  93  94  95  96  97  98  99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115
[116] 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138
[139] 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161
[162] 162