Difference between as.data.frame(x) and data.frame(x)

Question

What is the difference between as.data.frame(x) and data.frame(x)

In this following example, the result is the same at the exception of the columns names.

Answer 1

data.frame() can be used to build a data frame while as.data.frame() can only be used to coerce other object to a data frame.

for example:

# data.frame()
df1 <- data.frame(matrix(1:12,3,4),1:3)

# as.data.frame()
df2 <- as.data.frame(matrix(1:12,3,4),1:3)

df1
#   X1 X2 X3 X4 X1.3
# 1  1  4  7 10    1
# 2  2  5  8 11    2
# 3  3  6  9 12    3

df2
#   V1 V2 V3 V4
# 1  1  4  7 10
# 2  2  5  8 11
# 3  3  6  9 12