# declaring the columns of data frame
df = data.frame(
col1 = c('A', 'B', 'C', NA,'M'),
col2 = c(12.5, 9, 16.5, 20, 14.5),
col3 = c(NA, 3, 2, NA, 0))
# printing original data frame
print("Original data frame : ")
print(df)
# print("Renaming columns names ")
# renaming all the column names of data frame
df <- setNames(df, c("changed_Col1","changed_Col2","changed_Col3"))
print("Renamed data frame : ")
print(df)