R Language Learning Note 1

1. Chinese text mining software package: TMCN

2, used to eliminate the two vectors, lists, data frame, etc. in the same row or column function: Setdiff ()

3, create an empty array, used to load uncertain length data by: a <-numeric ()

4, convert the string format date to the date format with a function: As.date (), stored as a numeric value, for the standard format specified in R: year-month-day or year/month/day, you can do not need to specify the format of formats, if the input format is irregular, You need to read in the format specified by format.

To extract the numeric numbers 3 and 4 in the form {3,4}, the available methods are:

5. Appearance: Error in if (A & B): argument is of length zero error, its error is because one or more of the values in a or B are 0 or null, at which point the alternative method removes null or 0 values. If you are using which to determine if an element is contained in a vector, the error will appear in the following way:

if (which (Related==users.all[i]) ==as.integer (0)) {}
Error in if (which (related = = Users.all[i]) = = As.integer (0)) {: argument is of length zero

If the which determines that the vector does not contain the element, it indicates that the resulting vector length is 0, at which point the method can be used:

if (length (which (related==related)) ==0) {}

To solve the problem.