好了，所以我也有类似的这种结构的csv文件
hashID,value,flag
98fafd, 35, 1
fh56w2, 25, 0
ggjeas, 55, 1
adfh5d, 45, 0
基本上我想要做的就是值列的值，但只有包括行，其中flag==1在计算中。
这甚至可能在R' 我已搜索周围并没有发现这样的事。
Answer 1:
这是一种可能性：
使用下面的命令来读取你的数据集：
newdata <- read.csv("stackoverflow questions/mediancol.csv")
# I assume you have the data in csv format
# Showing the data I used for the computation
newdata <- structure(list(hashID = structure(c(1L, 3L, 4L, 2L), .Label = c("98fafd",
"adfh5d", "fh56w2", "ggjeas"), class = "factor"), value = c(35L,
25L, 55L, 45L), flag = c(1L, 0L, 1L, 0L)), .Names = c("hashID",
"value", "flag"), class = "data.frame", row.names = c(NA, -4L
))
> newdata
hashID value flag
1 98fafd 35 1
2 fh56w2 25 0
3 ggjeas 55 1
4 adfh5d 45 0
# Subset the data when flag =1
newdata1 <- subset(newdata,flag==1)
# Look at the summary of the data
> summary(newdata1)
hashID value flag
98fafd:1 Min. :35 Min. :1
adfh5d:0 1st Qu.:40 1st Qu.:1
fh56w2:0 Median :45 Median :1
ggjeas:1 Mean :45 Mean :1
3rd Qu.:50 3rd Qu.:1
Max. :55 Max. :1
# Only look at the median
median(newdata1$value)
[1] 45
Answer 2:
你也可以这样做在一个快速班轮与索引数据帧的布尔数组：
# read the data from a csv file
newdata <- read.csv("file.csv")
# this will give you a vector of boolean values of length nrow(newdata)
newdata$flag==1
# and this line uses the above vector to retrieve only those elements of
# newdata$value for which the row contains a flag value of 1
median(newdata$value[newdata$flag==1])
文章来源: Getting Median of a Column where value of another Column is 1 in R
