cd "C:\Users\Aki\Documents\stata"
log using feb28.log, replace

*******FEB 28. GRAPHING IN STATA. PART 2******
sysuse auto, clear
***dot chart
 graph dot (mean) price, over(rep78)
 //OR: go to Graphics menu - Dot chart - select the statistics to show and the categories
 //similar to bar chart
 
 ****DISTRIBUTIONAL PLOTS*****
 **it is useful to explore the distribution of key variables before running linear regressions and doing statistical tests
 
 **histogram, quantile density plot, kernel density plot
 histogram price
 //the variable price is not normally distributed
 histogram price, bin(20)
 histogram price, frequency
 
**k-density (kernel density) is a line-based representation of distribution
kdensity price
//the variable is not normally distributed

kdensity price if foreign==0
kdensity price if foreign ==1
graph twoway (kdensity price if foreign==0) (kdensity price if foreign==1)

quantile price
//useful to test for uniformal distribution. If a variable is distributed uniformally, the dots (observations) would be on the 45 degree line 


***BOX PLOT****
graph box price, over(foreign)
graph box price weight, over(foreign)
//useful to compare the distribution of a variable over different groups

***PIE CHART***
graph pie, over(rep78)

***SCATTERPLOTS WITH FITTED LINES****
scatter price mpg
twoway (scatter price mpg) (lfit price mpg)
//lfit is for linear fit
twoway (scatter price mpg) (qfit price mpg)
//qfit is for quadratic fit
**to let Stata decide on its own
twoway (scatter price mpg) (lpoly price mpg)
//looks more like a quasi-linear relationship

**CONTOUR PLOT****
***relationship between three continous variables. Used for mapping usually
sysuse sandstone, clear
twoway contour depth northing easting

**COMBINING GRAPHS***
// twoway () () is to combine graphs with common axis
sysuse auto, clear
twoway (scatter price mpg if foreign==1, title(Foreign)) (lfit price mpg if foreign==1, name(graph1))
twoway (scatter price mpg if foreign==0, title(Domestic)) (lfit price mpg if foreign==0, name(graph2))

graph combine graph1 graph2

****LOCAL AND GLOBAL MACROS AND LOOPING***
**local macros is some rule that you write yourself and which is valid only in one do-file and for a single execution of commands
*global macros work across all do-files and work until you close your Stata session (be careful with global macros)

local varlist "price mpg rep78"
sum `varlist'
tab rep78
sum `varlist'

global varlist "price mpg rep78"
sum $varlist
tab rep78
sum $varlist
reg trunk $varlist
//until you close your Stata session, this rule will apply

**looping
**want to generate a log for each var in the dataset
//can do it manually, using gen command
//gen logprice = log(price)
//gen logmpg = log(mpg)

foreach i in price mpg length {
	gen log`i' = log(`i')
    su log`i'	
	}

foreach var of varlist price - trunk {
	gen `var'10 = `var'*10
}

foreach var of varlist * {
gen `var'100 = `var'*100
}

log close