如何使用R按排序顺序读取目录中的文件？
下面给出的代码运行良好，读取了我的目录中的文件并提取了值：
X <- c(75:85) ; Y <- c(208:215)
extract <- vector()
files <- list.files("C:\\New folder (10)", "*.img",full.names=TRUE)
}我试图通过使用sprintf来指定它，但是我得到了错误。如果有任何帮助，请：
for (i in c(1:365)) {
fileName <- sprintf("C:New folder (10)/Climate_Rad_%d.img", i)
}回答 4
Stack Overflow用户
发布于 2012-05-28 07:36:01
为什么不使用list.files()检索所有文件(具有特定模式)，然后对其进行排序。然后从排序后的向量中检索文件，这将为您提供正确排序的文件。这样做的优点是，当1:365序列中缺少数字时，它也会起作用
类似于：
myFiles <- list.files(pattern = "^Climate_Rad_") #all files starting with Climate_
myFiles <- sort(myFiles)
# then read them in, for instance through
for (fileNames in myFiles) {READ.IN.AND.DO.YOUR.MAGIC.ON.THEM}Stack Overflow用户
发布于 2012-05-29 02:56:45
啊，好的，我明白了，问题出在分类上。排序顺序按字母顺序是正确的。Climate_Rad_1后面是字母顺序，后面是Climate_Rad_10，而不是Climate_Rad_2。这个顺序根本不是“随机”的，它是字母顺序正确的。
但是，您希望在Climate_Rad_10之前处理Climate_Rad_2，而不是在之后。有几种方法可以解决这个问题。首先，您应该注意到，Climate_Rad_002按字母顺序排在Climate_Rad_010之前，所以如果您在生成文件时添加前导零，这将使以后以数字顺序处理文件变得容易。
或者，让我们假设您在创建文件时不能添加零。那么至少有两种方法仍然可以按顺序访问文件。要么在文件名后添加零，要么只对文件名的数字部分进行排序。
让我向您展示后者。
myFiles <- paste("Climate_Rad_", c(1:15, 95:110), ".img", sep = "") # create some test names, you get the actual myFiles through a call to list.files()
myFiles.sorted <- sort(myFiles) # this gives the alphabetic sorting, not what you want
> myFiles.sorted
[1] "Climate_Rad_1.img" "Climate_Rad_10.img" "Climate_Rad_100.img"
[4] "Climate_Rad_101.img" "Climate_Rad_102.img" "Climate_Rad_103.img"
[7] "Climate_Rad_104.img" "Climate_Rad_105.img" "Climate_Rad_106.img"
[10] "Climate_Rad_107.img" "Climate_Rad_108.img" "Climate_Rad_109.img"
[13] "Climate_Rad_11.img" "Climate_Rad_110.img" "Climate_Rad_12.img"
[16] "Climate_Rad_13.img" "Climate_Rad_14.img" "Climate_Rad_15.img"
[19] "Climate_Rad_2.img" "Climate_Rad_3.img" "Climate_Rad_4.img"
[22] "Climate_Rad_5.img" "Climate_Rad_6.img" "Climate_Rad_7.img"
[25] "Climate_Rad_8.img" "Climate_Rad_9.img" "Climate_Rad_95.img"
[28] "Climate_Rad_96.img" "Climate_Rad_97.img" "Climate_Rad_98.img"
[31] "Climate_Rad_99.img"
# split between the part that comes before the numerics and the "1.img" etc.--adjust appropriately
split <- strsplit(myFiles.sorted, "Climate_Rad_")
# strip the "1.img" etc such that only the numeric part is left
# turn the characters in numeric
split <- as.numeric(sapply(split, function(x) x <- sub(".img", "", x[2])))
# not you can sort, by using order, that gives the original filenames, ordered on the numeric part of the filename
myFiles.correct.order <- myFiles.sorted[order(split)]
[1] "Climate_Rad_1.img" "Climate_Rad_2.img" "Climate_Rad_3.img"
[4] "Climate_Rad_4.img" "Climate_Rad_5.img" "Climate_Rad_6.img"
[7] "Climate_Rad_7.img" "Climate_Rad_8.img" "Climate_Rad_9.img"
[10] "Climate_Rad_10.img" "Climate_Rad_11.img" "Climate_Rad_12.img"
[13] "Climate_Rad_13.img" "Climate_Rad_14.img" "Climate_Rad_15.img"
[16] "Climate_Rad_95.img" "Climate_Rad_96.img" "Climate_Rad_97.img"
[19] "Climate_Rad_98.img" "Climate_Rad_99.img" "Climate_Rad_100.img"
[22] "Climate_Rad_101.img" "Climate_Rad_102.img" "Climate_Rad_103.img"
[25] "Climate_Rad_104.img" "Climate_Rad_105.img" "Climate_Rad_106.img"
[28] "Climate_Rad_107.img" "Climate_Rad_108.img" "Climate_Rad_109.img"
[31] "Climate_Rad_110.img"这将为您提供您要查找的文件顺序。现在根据这一点拉取文件，例如通过
for (fileNames in myFiles.correct.order) {READ.IN.AND.DO.YOUR.THING}这应该就行了。确保根据文件名调整"Climate_Rad_“和".img”(如果需要，您可能还需要在"Climate_Rad_“之前添加路径，以使其类似于”C:/filefolder/气候_Rad_“)。
Stack Overflow用户
发布于 2017-01-22 22:44:16
包有"mixedsort“功能，可以帮助你。
示例答案取自Peter Verbeet myFiles。
myFiles <- paste("Climate_Rad_", c(1:15, 95:110), ".img", sep = "")
install.packages ('gtools')
require ('gtools')
mixedsort (myFiles)
[1] "Climate_Rad_1.img" "Climate_Rad_2.img"
[3] "Climate_Rad_3.img" "Climate_Rad_4.img"
[5] "Climate_Rad_5.img" "Climate_Rad_6.img"
[7] "Climate_Rad_7.img" "Climate_Rad_8.img"
[9] "Climate_Rad_9.img" "Climate_Rad_10.img"
[11] "Climate_Rad_11.img" "Climate_Rad_12.img"
[13] "Climate_Rad_13.img" "Climate_Rad_14.img"
[15] "Climate_Rad_15.img" "Climate_Rad_95.img"
[17] "Climate_Rad_96.img" "Climate_Rad_97.img"
[19] "Climate_Rad_98.img" "Climate_Rad_99.img"
[21] "Climate_Rad_100.img" "Climate_Rad_101.img"
[23] "Climate_Rad_102.img" "Climate_Rad_103.img"
[25] "Climate_Rad_104.img" "Climate_Rad_105.img"
[27] "Climate_Rad_106.img" "Climate_Rad_107.img"
[29] "Climate_Rad_108.img" "Climate_Rad_109.img"
[31] "Climate_Rad_110.img"https://stackoverflow.com/questions/10777367
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