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我已经在增加光强度时测量了光合速率，以生成单个样品的 PI 曲线。我想通过将模型拟合到每个样本的测量响应来确定每条曲线的渐近线。下面是数据帧的一个子集，其中 O2_229、O2_35 等是单个样本。

A <- structure(list(LightIntensity = c(0, 112, 180, 272, 351, 430, 
482, 541, 609), O2_229 = c(-0.44673102313958, 0.0205958989967557, 
0.475351137678564, 0.640026082127451, 0.753504162148724, 
0.804818094545302, 0.84640533715284, 0.864374368585184, 
0.905709184251358), O2_35 = c(-0.302567249367208, 
0.181032510348939, 0.376659543810537, 0.496560233238315, 
0.540322247837853, 0.521608765794946, 0.528669387756481, 
0.516887809093099, 0.514844068198885), 
O2_230 = c(-0.542179874878379, 0.110661210104475, 
0.331450283334161, 0.568762984387555, 0.752938666550757, 
0.88143509214304, 0.945109493908027, 1.04005672006219, 
1.10246315337637), O2_36 = c(-0.510663216304597, 
0.509412237512078, 0.888867356301998, 1.18011410170533, 
1.28838854392113, 1.21645059640005, 1.29459817366225, 
1.02604605624222, 0.620845429599006), 
O2_Blank = c(-0.0291830039468955, -0.010410546520055, 
0.0414968296661793, 0.0398063330176891, -0.00945808361433628, 
-0.039882102158536, -0.0447402714742525, -0.0283811043764061, 
-0.0365212803552079)), row.names = c(NA, -9L), class = 
"data.frame")

到目前为止，这是我比较单个样本（O2_229）的模型的内容。我现在正试图确保找到最佳模型并确定每个样本曲线的渐近线。

A <- Data_9.20
linear.model <-lm(O2_229 ~ LightIntensity, A)
summary(linear.model)
plot(A$LightIntensity, A$O2_229)
abline(lm(O2_229 ~ LightIntensity, A))

light2 <- A$LightIntensity^2
quadratic.model <-lm(O2_229 ~ LightIntensity + light2, A)
summary(quadratic.model)
lightvalues <- seq(0, 700, 100)
predictedcounts <- 
predict(quadratic.model,list(LightIntensity=lightvalues, light2 = 
lightvalues^2)) 
plot(A$LightIntensity, A$O2_229)
lines(lightvalues, predictedcounts)
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1 回答 1

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我看到您正在使用二次方程对数据进行建模，该数据没有明确的渐近线。我发现带有偏移量的标准几何方程“y = a * pow(x, (b*x)) + Offset”似乎是一个很好的数据模型，其优点是“Offset”参数是显式拟合的渐近线。这是我对各种数据集（O2_Blank 除外）和模型图的拟合值。我注意到数据集 02_36 似乎是向下弯曲而不是接近渐近线。

data set O2_229:
a = -1.3851681272467806E+00
b = -1.0364478100088784E-03
Offset =  9.1626307846861987E-01

情节229

data set O2_35:
a = -8.4182899434390634E-01
b = -1.7580233358644494E-03
Offset =  5.3416172364897729E-01

情节35

data set O2_230:
a = -1.6587794258648598E+00
b = -7.2532639452267352E-04
Offset =  1.1581944009325142E+00

情节230

data set O2_36:
a = -1.6368370242440751E+00
b = -2.1647786145736897E-03
Offset =  1.1086452557429154E+00

情节36

于 2019-10-22T11:43:26.283 回答