Matías de Felipe - 3 months ago 13

R Question

I have three different treatments and within each one I have five sample values. I am into difficulties in how to sum the five values corresponding at each treatment.

Really I am working with a big dataframe which management is not too easy for me.

Below there is the dataframe

`dataexample_2`

`Treatment Variable`

A1 0.020408163

A1 0.040816327

A1 0.06122449

A1 0.081632653

A1 0.102040816

A2 0.12244898

A2 0.142857143

A2 0.163265306

A2 0.183673469

A2 0.204081633

A3 0.224489796

A3 0.244897959

A3 0.265306122

A3 0.285714286

A3 0.306122449

names(dataexample_2)

summary(dataexample_2)

Add<-sapply(split(dataexample_2, dataexample_2$Treatment), function(d) sum(dataexample_2$Variable,na.rm = FALSE))

Table<-as.data.frame(Add)

I am obtaining:

`Add`

A1 2.44898

A2 2.44898

A3 2.44898

And I wish to obtain:

`Add`

A1 0.3061

A2 0.8163

A3 1.3265

Any help will be really appreciated. Thanks in advance. Regards. MatÃas.

Answer

The problem with your code is that you refer to the whole data in your anonymus `function(d)`

instead of the current data `d`

.

The following corrected line does what you want:

```
sapply(split(dataexample_2, dataexample_2$Treatment), function(d) sum(d$Variable,na.rm = FALSE))
```

Also I would suggest that you have a look at `tapply`

which is better suited for the task you want to accomplish than `sapply`

. It can do the whole thing much clearer:

```
tapply(dataexample_2$Variable, dataexample_2$Treatment, sum)
```

Source (Stackoverflow)

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