EAS Department / Remote Sensing
Remote6-2c.doc (2 columns)
Plot – Scatter (scatter.pro)
Type in this information to create a graph
IDL> array=[[1,5],[2,8]]
IDL>print, array
IDL> plot,array
This is the output
1
5
2
8
This is the graph
Type in this information to create a graph
IDL> x=[1,5]
IDL> y=[2,8]
IDL> plot, x,y
This is the graph:
IDL>array=[[1,2],[5,8]]
IDL>print, array
IDL> plot,array
This is the result
___________________________________
____
These are the first 4 data rows from 589filter.txt
500.2
5.5
501.1
52.3225
502
52.28
502.9 49.95231
Xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Type in this program
pro newrsi
device, decomposed=0
;Look into various directories to load a file - looks for
'data1.txt'
;START 1------------FIND DATA FILE----------------filename = Dialog_Pickfile(Filter = '589.txt', /read)
get_lun, v
print, filename
openr, v, filename
;END 1------------------------------------------------------;START 2---------COUNT # LINES IN FILE --------a=' '
K=0
L=0
while ~ EOF(v) do begin
readf, v, a
k=k+1
endwhile
print, 'k=',k
close, v
free_lun, v
;END 2------------------------------------------------------;START 3----CREATE/PRINT DATA ARRAY ----GET_LUN, LUN
OPENR, LUN, FILENAME
array=fltarr(2,4) ;read a small fraction of the data file
readf, lun, array
PRINT, ARRAY ;print the whole array
print,array (0,1) ;print the first entry in this format
print,array (0,2)
print,array (1,0)
print, array(1,1)
;END 3------------------------------------------------------;plot, array
;END 6------------------------------------------------------end
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
This is the output
k= 662
500.200 5.50000
501.100 52.3225
502.000 52.2800
502.900 49.9523
501.100
502.000
5.50000
52.3225
so, the notation (0,1), (0,2) reads and prints the 2nd and 3rd
entry in column 1 (e.g. 501.1, 502.0) – this is the reverse of
typical mathematical notation
Therefore, place the columns first and the rows second. In
our case, we need a 2,4 matrix.
We can extract the x-values into an x-array (in this case 500,
501, etc.)
To extend the size of the array to include all the rows:
;START 3----CREATE AND PRINT DATA ARRAY
FROM DATA 1------------------
>array=fltarr(2,k)
Now, extract the x-column (really the second
column):
First, define 1-dimensional arrays (vectors) to hold
the data points:
>x=fltarr(k,1)
>y=fltarr(k,1)
Now fill these arrays accordingly
>x=array[0,*]
;remember that (0,0) = 500.2 and
(0,1)
; =501.1 so we are reading ;the
;mathematical column into an x-axis
array.
; END 3 ---------------------------------------------------------; START 4 ------------REVISE X,Y INTO PROPER
FORMAT---------------x=fltarr(k,1)
y=fltarr(k,1)
>y=array[1,*]
Now, x and y are in the usual format, but IDL needs
to be updated:
>x=reform(x)
>y=reform(y)
Now,
>plot, x, y
GET_LUN, LUN
OPENR, LUN, FILENAME
array=fltarr(2,k)
readf, lun, array
PRINT, ARRAY
print,array (0,1)
print,array (0,2)
print,array (1,0)
print, array(1,1)
;produces
x=array[0,*]
y=array[1,*]
x=reform(x)
y=reform(y)
; END 4 ----------------------------------------------; START 5 --------------PLOT X,Y ----------------------------plot,x,y
; END 5 -------------------------------------------------------------
end
This program should work:
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
pro newrsi2
;READS AND PLOTS A
SET OF X,Y DATA - EXPECTS NO HEADERS --
device, decomposed=0
;Look into various directories to load a file - looks
for 'data1.txt'
;START 1------------FIND DATA FILE---------filename = Dialog_Pickfile(Filter = '589.txt', /read)
get_lun, v
print, filename
openr, v, filename
;END 1------------------------------------------------------;START 2---------COUNT # LINES IN FILE AND
NUMBER OF HEADER LINES-----a=' '
K=0
L=0
while ~ EOF(v) do begin
readf, v, a
k=k+1
endwhile
print, 'k=',k
close, v
free_lun, v
;END 2------------------------------------------------------