Find the probability in 2nd column for a selection in 1st column - shell

Question

I have two columns as follows
ifile.dat
1 10
3 34
1 4
3 32
5 3
2 2
4 20
3 13
4 50
1 40
2 20
5 2
I would like to calculate the probability in 2nd column for some selection in 1st column.
ofile.dat
1-2 0.417 #Here 1-2 means all values in 1st column ranging from 1 to 2;
#0.417 is the probability of corresponding values in 2nd column
# i.e. count(10,4,2,40,20)/total = 5/12
3-4 0.417 #count(34,32,20,13,50)/total = 5/12
5-6 0.167 #count(3,2)/total = 2/12
Similarly if I choose the range of selection with 3 number, then the desire output will be
ofile.dat
1-3 0.667
4-6 0.333
RavinderSingh13 and James Brown had given nice scripts (see answer), but these are not working for lager values than 10 in 1st column.
ifile2.txt
10 10
30 34
10 4
30 32
50 3
20 2
40 20
30 13
40 50
10 40
20 20
50 2
~

Answer 1

EDIT2: Considering OP's edited samples could you please try following. I have tested it successfully with OP's 1st and latest edit samples and it worked perfectly fine with both of them.
Also one more thing, I made this solution such that a "corner case" where range could leave printing elements in case it is NOT crossing range value at last lines. Like OP's 1st sample where range=2 but max value is 5 so it will NOT leave 5 in here.
sort -n Input_file |
awk -v range="2" '
!b[$1]++{
c[++count]=$1
}
{
d[$1]=(d[$1]?d[$1] OFS:"")$2
tot_element++
till=$1
}
END{
for(i=1;i<=till;i++){
num+=split(d[i],array," ")
if(++j==range){
start=start?start:1
printf("%s-%s %.02f\n",start,i,num/tot_element)
start=i+1
j=num=""
delete array
}
if(j!="" && i==till){
printf("%s-%s %.02f\n",start,i,num/tot_element)
}
}
}
'
Output will be as follows.
1-10 0.25
11-20 0.17
21-30 0.25
31-40 0.17
41-50 0.17
EDIT: In case your Input_file don't have 2nd column then try following.
sort -k1 Input_file |
awk -v range="1" '
!b[$1]++{
c[++count]=$1
}
{
d[$1]=(d[$1]?d[$1] OFS:"")$0
tot_element++
till=$1
}
END{
for(i=1;i<=till;i+=(range+1)){
for(j=i;j<=i+range;j++){
num=split(d[c[j]],array," ")
total+=num
}
print i"-"i+range,tot_element?total/tot_element:0
total=num=""
}
}
'
Could you please try following, written and tested with shown samples.
sort -k1 Input_file |
awk -v range="1" '
!b[$1]++{
c[++count]=$1
}
{
d[$1]=(d[$1]?d[$1] OFS:"")$2
tot_element++
till=$1
}
END{
for(i=1;i<=till;i+=(range+1)){
for(j=i;j<=i+range;j++){
num=split(d[c[j]],array," ")
total+=num
}
print i"-"i+range,tot_element?total/tot_element:0
total=num=""
}
}
'
In case you don't have to include any 0 value then try following.
sort -k1 Input_file |
awk -v range="1" '
!b[$1]++{
c[++count]=$1
}
{
d[$1]=(d[$1]!=0?d[$1] OFS:"")$2
tot_element++
till=$1
}
END{
for(i=1;i<=till;i+=(range+1)){
for(j=i;j<=i+range;j++){
num=split(d[c[j]],array," ")
total+=num
}
print i"-"i+range,tot_element?total/tot_element:0
total=num=""
}
}
'

Answer 2

Another:
$ awk '
BEGIN {
a[1]=a[2]=1 # define the groups here
a[3]=a[4]=2 # others will go to an overflow group 3
}
{
b[(($1 in a)?a[$1]:3)]++ # group 3 defined here
}
END { # in the end
for(i in b) # loop all groups in no particular order
print i,b[i]/NR # and output
}' file
Output
1 0.416667
2 0.416667
3 0.166667
Update. Yet another awk with range configuration file. $1 is the start of range, $2 the end and $3 is the group name:
1 3 1-3
4 9 4-9
10 30 10-30
40 100 40-100
Awk program:
$ awk '
BEGIN {
OFS="\t"
}
NR==FNR {
for(i=$1;i<=$2;i++)
a[i]=$3
next
}
{
b[(($1 in a)?a[$1]:"others")]++ # the overflow group is now called "others"
}
END {
for(i in b)
print i,b[i]/NR
}' rangefile datafile
Output with both your datasets catenated together (and awk output piped to sort -n):
1-3 0.285714
4-9 0.142857
10-30 0.285714
40-100 0.142857