Description Usage Arguments Details Value Note Examples

Chain subset conditions

1 | ```
chainsubset(..., out.vars)
``` |

`...` |
Logical conditions to be chained. |

`out.vars` |
character. Variables not in data.frame, only needed if you use variables which
are not in the frame. If |

A set of logical conditions are chained, not and'ed. That is, each argument to
`chainsubset`

is used as a filter to create a smaller dataset. Each subsequent
argument filters further.
For independent conditions this will be the same as and'ing them. I.e.
`chainsubset(x < 0 , y < 0)`

will yield the same subset as `(x < 0) & (y < 0)`

.
However, for aggregate filters like `chainsubset(x < mean(y), x > mean(y))`

we first find all the observations with `x < mean(y)`

, then among these we
find the ones with `x > mean(y)`

. The last `mean(y)`

is now conditional on
`x < mean(y)`

.

Expression that can be `eval`

'ed to yield a logical subset mask.

Some trickery is done to make this work directly in the subset argument of functions like
`felm()`

and `lm()`

. It might possibly fail with an error message in some situations.
If this happens, it should be done in two steps: ```
ss <- eval(chainsubset(...),data);
lm(...,data=data, subset=ss)
```

. In particular, the arguments are taken literally,
constructions like `function(...) {chainsubset(...)}`

or `a <- quote(x < y); chainsubset(a)`

do
not work, but `do.call(chainsubset,list(a))`

does.

1 2 3 4 5 6 7 8 | ```
set.seed(48)
N <- 10000
dat <- data.frame(y=rnorm(N), x=rnorm(N))
# It's not the same as and'ing the conditions:
felm(y ~ x,data=dat,subset=chainsubset(x < mean(y), y < 2*mean(x)))
felm(y ~ x,data=dat,subset=chainsubset(y < 2*mean(x), x < mean(y)))
felm(y ~ x,data=dat,subset=(x < mean(y)) & (y < 2*mean(x)))
lm(y ~ x, data=dat, subset=chainsubset(x < mean(y), x > mean(y)))
``` |

lfe documentation built on May 1, 2019, 9:19 p.m.

Embedding an R snippet on your website

Add the following code to your website.

For more information on customizing the embed code, read Embedding Snippets.