[英]Cross-validating an ordinal logistic regression in R (using rpy2)
我正在嘗試在Python中創建一個預測模型,通過交叉驗證比較幾種不同的回歸模型。 為了適應序數邏輯模型( MASS.polr
),我必須通過rpy2
與R接口如下:
from rpy2.robjects.packages import importr
import rpy2.robjects as ro
df = pd.DataFrame()
df = df.append(pd.DataFrame({"y":25,"X":7},index=[0]))
df = df.append(pd.DataFrame({"y":50,"X":22},index=[0]))
df = df.append(pd.DataFrame({"y":25,"X":15},index=[0]))
df = df.append(pd.DataFrame({"y":75,"X":27},index=[0]))
df = df.append(pd.DataFrame({"y":25,"X":12},index=[0]))
df = df.append(pd.DataFrame({"y":25,"X":13},index=[0]))
# Loads R packages.
base = importr('base')
mass = importr('MASS')
# Converts df to an R dataframe.
from rpy2.robjects import pandas2ri
pandas2ri.activate()
ro.globalenv["rdf"] = pandas2ri.py2ri(df)
# Makes R recognise y as a factor.
ro.r("""rdf$y <- as.factor(rdf$y)""")
# Fits regression.
formula = "y ~ X"
ordlog = mass.polr(formula, data=base.as_symbol("rdf"))
ro.globalenv["ordlog"] = ordlog
print(base.summary(ordlog))
到目前為止,我主要使用sklearn.cross_validation.test_train_split
和sklearn.metrics.accuracy_score
比較我的模型, sklearn.metrics.accuracy_score
的數字從0到1,代表訓練集模型預測測試集值的准確性。
如何使用rpy2
和MASS.polr
復制此測試?
通過使用rms.lrm
重新擬合模型最終解決了問題,該模型提供了validate()
函數(在此示例之后進行解釋)。
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