運行此代碼后，我沒有在 Firas 頻譜的 R 中獲得預期的 output

Question

我正在嘗試運行下面的代碼，可以從https://lambda.gsfc.nasa.gov/data/cobe/firas/monopole_spec/firas_monopole_spec_v1.txt訪問數據

#loading the data 
cobe <- read.table("~/Downloads/cobe.txt", quote="\"")

frequency <- (cobe$V1)*29.979
spectrum <- cobe$V2

B_f <- function(frequency, t){

h <- 6.62607015e-34
c <- 299792458
k <- 1.380649e-23
spectrum <- ((2*h*frequency^3)/c^2)/exp((h*frequency)/k*t)-1
return(spectrum * 1e-9)
}

t <- 2.725
spectrum <- B_f(frequency,t)

library(ggplot2)



ggplot(data = data.frame(frequency, spectrum)) + 
geom_line(aes(x = frequency, y = spectrum)) + 
ggtitle("Blackbody spectrum at T = 2.725K \n with data from the COBE satellite") + 
xlab("Frequency (GHz)") + ylab("Spectral Radiance (MJy/sr)") + 
theme_classic()+

geom_point(aes(x = frequency, y = spectrum), color = 'red', size = 5)

我不斷得到第一張圖片（直線水平圖），但我期待第二張圖（BB 曲線） output plot [2]預期 plot 。

Answer 1

根據您提供的來源，我認為您進行了不必要的轉換：

#loading the data 
cobe <- read.table("~/Downloads/cobe.txt", quote="\"")

library(ggplot2)

ggplot(data = cobe, aes(x = V1, y = V2)) + 
  geom_line(colour = "blue") + 
  ggtitle("Blackbody spectrum at T = 2.725K \n with data from the COBE satellite") + 
  xlab("Frequency (cycles/cm)") + ylab("Spectral Radiance (MJy/sr)") + 
  theme_classic()+
  geom_point(aes(x = frequency, y = spectrum), color = 'red', size = 5)

產生一個 plot 來匹配我認為的預期圖像？