Nice Girl - 4 months ago 21

R Question

`summary(as.factor(qanswer$q41))`

1 B C D E NA's

112 66 127 45 30 896

I just want to get the number of 1,which is 112.then i tried:

`length(qanswer$q41[qanswer$q41==1])`

[1] 1008

> length(qanswer$q41[qanswer$q41=='1'])

[1] 1008

> length(qanswer$q41[qanswer$q41=='A'])

[1] 896

> length(qanswer$q41[qanswer$q41=='B'])

[1] 962

I made a function:

`x<-function(column){sum(column=='1',na.rm = TRUE)/sum(column,na.rm = TRUE)}`

> x(qanswer$q41)

Error in sum(column, na.rm = TRUE) :

invalid 'type' (character) of argument

what's the problem?

Answer

We can use `sum`

```
sum(qanswer$q41==1, na.rm = TRUE)
```

As there are NA values in the 'q41' column, the `==`

returns NA for those NA elements and by subsetting `qanswer$q41[qanswer$q41==1]`

, the length will also include the 896 NAs, i.e.

```
896+ 112 = 1008
```

Instead, we need to make sure that the NAs are either removed (`na.rm=TRUE`

) in the `sum`

or use `!is.na`

if we wanted to try with `length`

```
length(qanswer$41[qanswer$q41==1 & !is.na(qanswer$q41)])
```