r - How to find a data frame in a list from its attribute value? -

i have several data frames each represent data in given condition.

for instance, df.1 data measured @ temperature t1, df.2 @ temperature t2, , on.

i have set attribute temperature each data frame , stored data frames in list.

now want retrieve data frame given temperature.

so have 2 questions:

• is attribute/list approach recommended one?

• is there elegant way retrieve data frame appropriate temperature? see way loop, wonder if there better solution.

here example code:

x <- seq(0, 50, = 0.1) y1 <- sin(x) y2 <- cos(x) df.1 <- data.frame(time = x, value = y1) attr(df.1, "temperature") <- 20.0 df.2 <- data.frame(time = x, value = y2) attr(df.2, "temperature") <- 30.0  df.list <- list(df.1, df.2)  result <- null (df in df.list) {   if (attr(df, "temperature") == 20) {     result <- df   } } 

it's advisable provide appropriate names list created, e.g.

names(df.list) <- c("t20", "t30") 

this way, can call out appropriate table according names, e.g.

head(df.list[["t20"]])   time      value 1  0.0 0.00000000 2  0.1 0.09983342 3  0.2 0.19866933 4  0.3 0.29552021 5  0.4 0.38941834 6  0.5 0.47942554  head(df.list[["t30"]])   time     value 1  0.0 1.0000000 2  0.1 0.9950042 3  0.2 0.9800666 4  0.3 0.9553365 5  0.4 0.9210610 6  0.5 0.8775826