可以打印超过 100 行的 data.table 吗？

Question

The data.table has a nice feature that suppresses output to the head and tail of the table.

Is it possible to view / print more than 100 rows at once?

library(data.table)
## Convert the ubiquitous "iris" data to a data.table
dtIris = as.data.table(iris)
## Printing 100 rows is possible
dtIris[1:100, ]
## Printing 101 rows is truncated
dtIris[1:101, ]

I often have data.table results that are somewhat large (eg 200 rows) that I just want to view.

Answer 1

The print method of data.table has an argument nrows :

args(data.table:::print.data.table)
function (x, nrows = 100L, digits = NULL, ...) 

You can use this to control how many rows get printed:

print(dtIris, nrow=105)
.....
99:          5.1         2.5          3.0         1.1 versicolor
100:          5.7         2.8          4.1         1.3 versicolor
101:          6.3         3.3          6.0         2.5  virginica
102:          5.8         2.7          5.1         1.9  virginica
103:          7.1         3.0          5.9         2.1  virginica
104:          6.3         2.9          5.6         1.8  virginica
105:          6.5         3.0          5.8         2.2  virginica
     Sepal.Length Sepal.Width Petal.Length Petal.Width    Species

Answer 2

View() （如在View(iris)或View(dtIris[1:120,])中）不会截断data.table ，并且通常比打印/喷出data.*到控制台更好。

Answer 3

打印前 60 行和后 60 行（默认为前 5 行和后 5 行）：

print(dtIris, topn = 60)

Answer 4

You could convert it to a data.frame only for printing:

iris_dt = as.data.table(iris)
print(as.data.frame(iris_dt))

Answer 5

A messy option, but you could always export it into excel to view it with excels convenience.

library(xlsReadWrite)
write.xls(mydata, "c:/mydata.xls")