Mat Operation Use Selected Observation Stata

This function is similar to using inlist or inrange with if as mentioned above.

Mat operation use selected observation stata. In principle the problem is perfectly programmable as a stata program writing a version of mata s select but writing extensions to stata s matrix language peaked about 20 years ago. Matrix operations in stata. The variable nvals now contains the number of distinct observations. Matrix addition subtraction mat b 1 1 4 2 2 1 mat c a b mat lis.

During the loading process so n 100 is false. Although we chose to tag the first observation in each group as was specified by n 1 we could have done it also for the last observation in each group for which the code is n n. The if and in keywords on a command can be used to limit the analysis on a selection of observations filter observations for analysis. Multiplication by a scalar mat b 3 a mat lis b b 3 2 c1 c2 r1 6 3 r2 9 6 r3 6 6.

Moreover even if stata could hold the n k matrix x it would still be more efficient to use matrix accum to form x 0 x. 14 1 2 matsize matrices are limited to being no larger than matsize matsize. List the last ten observations you can use l for last and f for first. Anymatch in stata 9 and later releases is a replacement for eqany in stata 8 and prior releases.

By default stata commands operate on all observations of the current dataset. Officially correct syntax is use if n 100 using mydata or better yet use in 1 99 using mydata this latter syntax is much more efficient. In this problem the result is the same. You probably mean n little n rather than n.

Using the transpose of a for the first matrix which also interchanged the names and so obtained the names shown. Crucially the argument of values may be a numlist so to give only one example unbroken sequences of integers may be specified concisely. I suppose n is. A deeper question is where this matrix comes from and what it is being used for and so whether there is a better way of working altogether.

The default value of matsize is 400 for stata mp stata se and stata ic but you can reset this with the set matsize command. You may want to be careful when using the list command. In this case the census dta is a small dataset with only 50 rows observations in it and i eliminated 33 observations so i know i only have a fairly small number of cases to be listed in the output.