@eqna—599

Date-TO-Observation. Returns the observation number corresponding to the date contained in the string. The observation number is relative to the start of the current workfile range, not the current sample. Observation numbers may be used to select a particular element in a vector that has been converted from a series, provided that NAs are preserved (see stomna (p. 627)).

Examples:

scalar obnum = @dtoo("1994:01")

vec1(1) = gdp(@dtoo("1955:01")+10)

Suppose that the workfile contains quarterly data. Then the second example places the 1957:02 value of the GDP series in the first element of VEC1.

Note that @DTOO will generate an error if used in a panel structured workfile.

See also @otod (p. 605).

Tests for equality of str1 and str2, treating null strings as ordinary blank strings, and not as missing values. Strings which test as equal return a 1, and 0 otherwise.

Example:

@eqna("abc", "abc")

returns a 1, while

@eqna("", "def")

returns a 0.

@left—601

Tests for whether str is a blank string, returning a 1 if str is a null string, and 0 otherwise.

Example:

@isempty("1.23415")

returns a 0, while

@isempty("")

return the value 1.

See also @len, @length (p. 602).

Returns a string containing n characters from the left end of str. If the string is shorter than n characters, this function returns all of the characters in the source string.

Example:

scalar sc1 = @left("I did not do it",5)

returns “I did”.

See also @right (p. 606), and @mid (p. 603).