最后一次观察结果在多个柱上进行 [英] Last observation carried forward by group over multiple columns

问题描述

我有一个数据集，观察多个患者及其随时间的诊断。有9个不同的虚拟变量，每个代表一个特定的诊断，命名为例如。 L40，L41，K50，M05等。

I have a dataset with observations of multiple patients and their diagnoses over time. There are 9 different dummy variables, each representing a specific diagnosis, named e.g. L40, L41, K50, M05 and so on.

如果虚拟变量中有缺失值，我想结束患者的最后一个非缺失值，使得一旦患者接收到诊断，其将遵循到随后的观察。

Where there are missing values in the dummy variables, I want to carry forward the last non-missing value by patient, so that once a patient receives a diagnosis, it will follow through to subsequent observations.

我开始使用动物园软件包中的na.locf函数。

I started with this, using the na.locf function from the zoo package.

diagdata <- originaldata[,grep("^patient|^ar|^edatum|^K|^L|^M",colnames(originaldata))]

require(zoo)
require(data.table)

diagnosis <- data.table(diagdata)

diagnosis[,L40:=na.locf(L40),by=patient]

这实现了我正在寻找的东西， L40）。是否有任何方法将上述应用于所有相关的诊断列，即以K，L和M开头的列？

This achieves what I am looking for, but only on the column in question (L40). Is there any way of applying the above to all the relevant diagnosis columns, i.e. columns starting with K, L and M?

推荐答案

cols = grep("^K|^L|^M", names(diagnosis), value = T)

diagnosis[, (cols) := na.locf(.SD, na.rm = F), by = patient, .SDcols = cols]

另请参阅按组中的有效locf单R数据表。

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