CODEWITHSUNDEEP
rexcelif-statement
She632
She632

Reputation: 53

Translating IF condition from Excel to R

I have the following data

A B C D E
1 Date Temp.10 values Criteria
2 10/08/2020 1 0
3 11/08/2020 1 0
4 12/08/2020 1 0 0
5 13/08/2020 1 3 0
6 14/08/2020 1 13 0
7 15/08/2020 1 15 0
8 16/08/2020 1 7 1
9 17/08/2020 1 6 1
10 18/08/2020 1 0 1
11 19/08/2020 1 25 0

To meet the criteria (=1) the two previous days must have values higher than 5. In Excel I would just place my self in cell E4 and type:

=IF(AND(D3>5,D2>5),1,0)

And then pull down the formula.

I am trying to write this in R, but I am not succeeding!

Help much appreciated thank you :)

Upvotes: 0

Views: 69

Answers (2)

Captain Hat
Captain Hat

Reputation: 3237

R syntax is quite different from Excel. I'll show you:

AND

Excel: AND(this, that)

R: this & that

IF

Excel: IF(condition, expression, otherwise)

R:

if(condition){
expression
} else {
otherwise
}

alternatively: ifelse(condition, expression, otherwise)

Indexing

There's no need for, or possibility of, clicking-and-dragging in R. Lots of functions, including &, can deal with vectorised input. (But note that if does not.)

To index a 'previous' value, you'll need to use the lag() function.

The equivalent of =IF(AND(D3>5,D2>5),1,0) is just (lag(D,1) > 5) & (lag(D,2) > 5)), where D is a numeric vector.

If your data is a matrix or data.table, you can get D with df[,4] where df is the name of your talbe and, as in your example, D is the fourth column. Alternatively if your columns are named, you can use df[,"D"]. So the code would be something like:

(lag(df[,"D"], 1) > 5) & (lag(df[,"D"], 2) > 5)

The above will return a logical vector with TRUE/FALSE values. If you want 1's and 0's, put the whole thing inside as.numeric().

Upvotes: 2

Gregor Thomas
Gregor Thomas

Reputation: 145775

With dplyr:

library(dplyr)
your_data %>%
  mutate(
    Criteria = ifelse(lag(values, 1) > 5 & lag(values, 2) > 5, 1, 0)
  )

Upvotes: 3

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