# Sample data
df <- tibble(id=1:2, xml_str=c("<?xml version='1.0'?><!DOCTYPE svg PUBLIC '-//W3C//DTD SVG 1.1//EN' 'http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd'><svg version='1.1' xmlns='http://www.w3.org/2000/svg'>'/>\n<path fill='none' stroke='#ff0000' stroke-width='5' d='M171, 160 L171, 160, 168, 159, 164, 159, 163, 159, 162, 159, 161, 159, 161, 158, 162, 158, 162, 157, 163, 156, 165, 156'/>'/>\n<path fill='none' stroke='#ff0000' stroke-width='5' d='M172, 226 L172, 226, 171, 213, 170, 212, 171, 212, 172, 212, 173, 212, 173, 211, 172, 211, 171, 211, 171, 212, 171, 215'/>\n<path fill='none' stroke='#ff0000' stroke-width='5' d='M153, 94 L153, 94, 150, 90, 150, 89, 150, 88, 150, 87, 150, 86, 150, 85, 150, 84, 150, 82, 150, 81, 150, 80, 150, 79'/>'/>'/>'/>\n<path fill='none' stroke='#ff0000' stroke-width='5' d='M346, 84 L346, 84, 346, 79, 347, 78, 347, 77, 348, 77, 348, 76, 348, 75, 348, 76, 348, 77, 349, 77, 348, 78'/>\n<path fill='none' stroke='#ff0000' stroke-width='5' d='M314, 67 L314, 67, 311, 76, 309, 76, 308, 77, 307, 77, 307, 76, 306, 76, 305, 76, 305, 77, 306, 77, 307, 77, 306, 77, 305, 79, 304, 80'/>\n<path fill='none' stroke='#ff0000' stroke-width='5' d='M313, 57 L313, 57, 321, 56, 321, 57, 321, 58'/>\n<path fill='none' stroke='#ff0000' stroke-width='5' d='M332, 58 L332, 58, 332, 57, 331, 57, 333, 57, 334, 57, 335, 57, 336, 58, 337, 58, 338, 58, 339, 58, 340, 58, 341, 58, 341, 59, 340, 60, 339, 60, 338, 60, 337, 60, 336, 60, 335, 60, 334, 60, 333, 60, 332, 60, 331, 60, 331, 59, 333, 58, 334, 58'/></svg>", "<?xml version='1.0'?><!DOCTYPE svg PUBLIC '-//W3C//DTD SVG 1.1//EN' 'http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd'><svg version='1.1' xmlns='http://www.w3.org/2000/svg'>\n<path fill='none' stroke='#ff0000' stroke-width='5' d='M315, 80 L315, 80, 321, 79, 320, 79, 318, 79, 317, 79'/>\n<path fill='none' stroke='#ff0000' stroke-width='5' d='M334, 83 L334, 83, 334, 82'/>\n<path fill='none' stroke='#ff0000' stroke-width='5' d='M315, 80 L315, 80, 315, 82, 315, 83, 315, 84, 315, 85'/>\n<path fill='none' stroke='#ff0000' stroke-width='5' d='M315, 72 L315, 72'/>\n<path fill='none' stroke='#ff0000' stroke-width='5' d='M315, 69 L315, 69, 315, 70'/>\n<path fill='none' stroke='#ff0000' stroke-width='5' d='M332, 66 L332, 66, 332, 67'/>\n<path fill='none' stroke='#ff0000' stroke-width='5' d='M315, 56 L315, 56'/>\n<path fill='none' stroke='#ff0000' stroke-width='5' d='M315, 66 L315, 66, 315, 67'/>\n<path fill='none' stroke='#ff0000' stroke-width='5' d='M315, 72 L315, 72'/>\n<path fill='none' stroke='#ff0000' stroke-width='5' d='M332, 72 L332, 72, 333, 75'/>\n<path fill='none' stroke='#ff0000' stroke-width='5' d='M315, 72 L315, 72'/>\n<path fill='none' stroke='#ff0000' stroke-width='5' d='M334, 73 L334, 73, 333, 73'/></svg>"))
df <- df %>%
rowwise() %>%
mutate(nodes = (xml_str %>% read_xml() %>% xml_find_all(., "//@d") %>% as_list()))
使用上面的数据框，我想从xml字符串中提取所有路径元素的d节点，并将它们作为列表存储在同一个数据框中，但我得到的列nodes必须是长度为1（团体规模），而不是7
mutate语句中使用的管道确实返回单个列表。
我可以省略'rowwise（）'，但只需要长度为2而不是1。
我在这里缺少什么？
答案 0 :(得分：1)
这不完全是你的方式，但你可以使用str_extract_all和regex将相关的字符串拉出来作为逗号分隔字符串的列表
ans <-
df %>%
dplyr::mutate(dnodes = stringr::str_extract_all(xml_str, "(?<=[d]=')[^']+(?='\\/)"))
ans$dnodes
# [[1]]
# [1] "M171, 160 L171, 160, 168, 159, 164, 159, 163, 159, 162, 159, 161, 159, 161, 158, 162, 158, 162, 157, 163, 156, 165, 156"
# [2] "M172, 226 L172, 226, 171, 213, 170, 212, 171, 212, 172, 212, 173, 212, 173, 211, 172, 211, 171, 211, 171, 212, 171, 215"
# [3] "M153, 94 L153, 94, 150, 90, 150, 89, 150, 88, 150, 87, 150, 86, 150, 85, 150, 84, 150, 82, 150, 81, 150, 80, 150, 79"
# [4] "M346, 84 L346, 84, 346, 79, 347, 78, 347, 77, 348, 77, 348, 76, 348, 75, 348, 76, 348, 77, 349, 77, 348, 78"
# [5] "M314, 67 L314, 67, 311, 76, 309, 76, 308, 77, 307, 77, 307, 76, 306, 76, 305, 76, 305, 77, 306, 77, 307, 77, 306, 77, 305, 79, 304, 80"
# [6] "M313, 57 L313, 57, 321, 56, 321, 57, 321, 58"
# [7] "M332, 58 L332, 58, 332, 57, 331, 57, 333, 57, 334, 57, 335, 57, 336, 58, 337, 58, 338, 58, 339, 58, 340, 58, 341, 58, 341, 59, 340, 60, 339, 60, 338, 60, 337, 60, 336, 60, 335, 60, 334, 60, 333, 60, 332, 60, 331, 60, 331, 59, 333, 58, 334, 58"
# [[2]]
# [1] "M315, 80 L315, 80, 321, 79, 320, 79, 318, 79, 317, 79" "M334, 83 L334, 83, 334, 82"
# [3] "M315, 80 L315, 80, 315, 82, 315, 83, 315, 84, 315, 85" "M315, 72 L315, 72"
# [5] "M315, 69 L315, 69, 315, 70" "M332, 66 L332, 66, 332, 67"
# [7] "M315, 56 L315, 56" "M315, 66 L315, 66, 315, 67"
# [9] "M315, 72 L315, 72" "M332, 72 L332, 72, 333, 75"
# [11] "M315, 72 L315, 72" "M334, 73 L334, 73, 333, 73"
您可以使用
转换为字符串向量列表ans <-
df %>%
dplyr::mutate(dnodes = stringr::str_extract_all(xml_str, "(?<=[d]=')[^']+(?='\\/)")) %>%
dplyr::mutate(dnodes = purrr::map(dnodes, ~unlist(strsplit(paste(.x, collapse=", "), ", "))))
ans$dnodes
# [[1]]
# [1] "M171" "160 L171" "160" "168" "159" "164" "159" "163" "159" "162"
# [11] "159" "161" "159" "161" "158" "162" "158" "162" "157" "163"
# [21] "156" "165" "156" "M172" "226 L172" "226" "171" "213" "170" "212"
# [31] "171" "212" "172" "212" "173" "212" "173" "211" "172" "211"
# [41] "171" "211" "171" "212" "171" "215" "M153" "94 L153" "94" "150"
# [51] "90" "150" "89" "150" "88" "150" "87" "150" "86" "150"
# [61] "85" "150" "84" "150" "82" "150" "81" "150" "80" "150"
# etc
答案 1 :(得分：1)
这样做你想要的吗？我通常将mutate(name = right_side)的{{1}}的右侧包裹在list()中以实现此目的。
df <- df %>%
mutate(nodes = list(xml_str %>% read_xml() %>% xml_find_all(., "//@d")))
class(df$nodes)
"list"
class(df$nodes[[1]])
"xml_nodeset"
不确定您是否想要xml_nodeset个对象，或者CPak的解决方案是否更适合您。