Can I use R to get a category count for every time an item in a vector pertains to a certain category?

user_15664927 0
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I am a novice R user hoping for some help:

I want to write some code where I can input a vector and determine how many times each item fell within a category. For example, if I had three categories in a data frame and a vector in question:

```
fruits<-c("Apple","Banana","Pear")
vegetables<-c("Broccoli","Spinach","Peas")
flowers<-c("Rose","Daisy","lily")

df<-cbind(fruits,vegetables,flowers)

df

vectorinquestion<-c("Banana","Peas","Apple")
```

What kind of code can I use to get the output of:

Fruit = 2
Vegetable = 1
Flower = 0

Any help with this would be greatly appreciated! I am trying to learn new functions, so this would help a lot.

categories grouping vector count r
1 Answers

You can loop apply %in%, creating a logical matrix.


logical_matrix<-sapply(df, function(x) vectorinquestion %in% x)
> logical_matrix
     fruits vegetables flowers
[1,]   TRUE      FALSE   FALSE
[2,]  FALSE       TRUE   FALSE
[3,]   TRUE      FALSE   FALSE

Then you can loop apply a function to sum your TRUEs for every column:

> colSums(logical_matrix)
    fruits vegetables    flowers 
         2          1          0

All in a one-liner:

colSums(sapply(df, function(x) vectorinquestion %in% x)

With purrr:

df%>%map(~vectorinquestion %in% .)%>%cbind.data.frame()%>%colSums()
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