使用 R 中的条件替换列中的值 [英] Replacing values from a column using a condition in R

问题描述

我有一个非常基本的 R 问题，但我很难找到正确的答案.我有一个如下所示的数据框:

I have a very basic R question but I am having a hard time trying to get the right answer. I have a data frame that looks like this:

 ind<-rep(1:4,each=24)
 hour<-rep(seq(0,23,by=1),4)
 depth<-runif(length(ind),1,50)

 df<-data.frame(cbind(species,ind,hour,depth))
 df$depth<-as.numeric(df$depth)

我希望它选择并替换 depth <的所有行10(例如)为零，但我想保留与这些行相关的所有信息以及数据框的原始维度.

What I would like it to select AND replace all the rows where depth < 10 (for example) with zero, but I want to keep all the information associated to those rows and the original dimensions of the data frame.

我尝试了以下方法，但这不起作用.

I have try the following but this does not work.

df[df$depth<10]<-0

有什么建议吗?

推荐答案

# reassign depth values under 10 to zero
df$depth[df$depth<10] <- 0

(对于因子列，您只能分配因子级别的值.如果要分配当前不是因子级别的值，则需要先创建附加级别:

(For the columns that are factors, you can only assign values that are factor levels. If you wanted to assign a value that wasn't currently a factor level, you would need to create the additional level first:

levels(df$species) <- c(levels(df$species), "unknown") 
df$species[df$depth<10]  <- "unknown" 

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