Create new column with binary data or presence/absence data in R [duplicate]

问题

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How to add a factor column to dataframe based on a conditional statement from another column? (1 answer)

Closed 7 years ago.

The answer to the following question has been addressed more simply than this answer: Create new column with binary data based on several columns

I am trying to create a new column of binary data (presence/absence data) based on another column in R.

I want "Species_code" rows with the number 101 to produce a 1 in the new "Presence_absence" column; everything else should produce a 0.

Here is what I want the new Presence_absence column to look like:

Species_code       Presence_absence
101                1
103                0
101                1
99                 0
101                1

回答1:

Use ifelse:

> df <- data.frame(Species_code = c(101, 103,101,99,101)) # your data
> df$Presence_absence <- ifelse(df$Species_code==101, 1, 0) # this does the trick
> df
  Species_code Presence_absence
1          101                1
2          103                0
3          101                1
4           99                0
5          101                1

来源：https://stackoverflow.com/questions/18818763/create-new-column-with-binary-data-or-presence-absence-data-in-r