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在R中创建具有特定迭代的列表

iteration for-loop loops list r

0

GCGM · 技术社区 · 6 年前

我有以下包含日期的数据集:

> dates
 [1] "20180412" "20180424" "20180506" "20180518" "20180530" "20180611" "20180623" "20180705" "20180717" "20180729"

我试图创建一个列表,在每个位置,名字是'连贯性'+的第一和第二个日期 dates . 所以在 output1[1] 我会的 Coherence_20180412_20180424 . 然后在 output1[2] 我会的 Coherence_20180506_20180518

我从这个代码开始,但它不是我所需要的工作方式:

output1<-list()
for (i in 1:5){
  output1[[i]]<-paste("-Poutput1=", S1_Out_Path,"Coherence_VV_TC", dates[[i]],"_", dates[[i+1]], ".tif", sep="")
}

你有什么建议吗?

3 回复 | 直到 6 年前

1

Saurabh Chauhan 6 年前

无回路

even_indexes<-seq(2,10,2) # List of even indexes
odd_indexes<-seq(1,10,2)  # List of odd indexes
print(paste('Coherence',paste(odd_indexes,even_indexes,sep = "_"),sep = "_"))

从这里链接答案: Create list in R with specific iteration

更新 (获取列表中的数据)

lst=c(paste('Coherence',paste(odd_indexes,even_indexes,sep = "_"),sep = "_"))

或者

a=c(1:10)
for (i in seq(1, 9, 2)){
 print(paste('Coherence',paste(a[i],a[i+1],sep = "_"),sep = "_"))
}

输出:

[1] "Coherence_1_2"
[1] "Coherence_3_4"
[1] "Coherence_5_6"
[1] "Coherence_7_8"
[1] "Coherence_9_10"

2

1

Silpara 6 年前

paste 操作矢量的能力:

dates <- c("20180412", "20180424", "20180506", "20180518", "20180530", 
"20180611", "20180623", "20180705", "20180717", "20180729")
paste("Coherence", dates[1:length(dates)-1], dates[2:length(dates)], sep="_")
[1] "Coherence_20180412_20180424" "Coherence_20180424_20180506" "Coherence_20180506_20180518"
[4] "Coherence_20180518_20180530" "Coherence_20180530_20180611" "Coherence_20180611_20180623"
[7] "Coherence_20180623_20180705" "Coherence_20180705_20180717" "Coherence_20180717_20180729"

或者其他简单模式可以生成为:

paste("Coherence", dates[seq(1, length(dates), 2)], dates[seq(2, length(dates), 2)], sep="_")
[1] "Coherence_20180412_20180424" "Coherence_20180506_20180518" "Coherence_20180530_20180611"
[4] "Coherence_20180623_20180705" "Coherence_20180717_20180729"

3

0

jogo 6 年前

你可以用 matrix(..., nrow=2) :

dates <- c("20180412", "20180424", "20180506", "20180518", "20180530", "20180611", "20180623", "20180705", "20180717", "20180729")
paste0("Coherence_", apply(matrix(dates, 2), 2, FUN=paste0, collapse="_"))
# > paste0("Coherence_", apply(matrix(dates, 2), 2, FUN=paste0, collapse="_"))
# [1] "Coherence_20180412_20180424" "Coherence_20180506_20180518" "Coherence_20180530_20180611" "Coherence_20180623_20180705"
# [5] "Coherence_20180717_20180729"