# Write a function called get_distance that accepts two character vector inputs representing the names of two cities. The function returns the distance between them as an output argument called distance. For example, the call get_distance('Seattle, WA'

16 visualizaciones (últimos 30 días)
Abhishek singh el 17 de Abr. de 2019
Respondida: Pascal el 15 de Jun. de 2023
function distance = get_distance(x,y)
col_labels = raw(1,:);
row_labels = raw(:,1);
try
distance = raw{contains(row_labels,y),contains(col_labels,x)};
catch
distance = -1;
end
end
error
Assessment result: incorrectNashville, TN and Las Vegas, NV
Variable distance has an incorrect value.
Assessment result: incorrectRandom city pairs
Variable distance has an incorrect value.
get_distance('Chattanooga, TN','Meads, KY') returned -1 which is incorrect.
##### 0 comentariosMostrar -2 comentarios más antiguosOcultar -2 comentarios más antiguos

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### Respuestas (22)

Arafat Roney el 6 de Mayo de 2020
function distance=get_distance(a,b)
row=raw(1,:);
col=raw(:,1);
for ii=2:length(row)
if strcmp(row(ii),a)
mii=ii;
break;
end
end
for jj=2:length(col)
if strcmp(col(jj),b)
njj=jj;
break;
end
end
if (strcmp(row(ii),a))&&(strcmp(col(jj),b))
distance=raw{mii,njj};
else
distance=-1;
end
end
##### 6 comentariosMostrar 4 comentarios más antiguosOcultar 4 comentarios más antiguos
SOUMYAJIT MONDAL el 20 de Ag. de 2021
Okay ,
if raw(1,;) represents the first row of that cell array then row=raw(,;) should also be selecting the first row. So 'row' is not initialised as a vector ,but in the for loop 'row' is used as a vector ex. row(1) , row(2), ....
Walter Roberson el 20 de Ag. de 2021

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Mati Somp el 6 de Oct. de 2020
one more
function distance = get_distance(A,B)
ii=0;
jj=0;
for i=2:length(data)
if string(A)==string(txt{1,i})
ii=i;
end
if (string(B)==string(txt{1,i}))
jj=i;
end
end
if (~(jj) || ~(ii))
distance=-1;
else
distance=data(ii-1,jj-1);
end
##### 2 comentariosMostrar NingunoOcultar Ninguno
THIERNO AMADOU MOUCTAR BALDE el 30 de Dic. de 2020
perfect
Kulko Margarita el 12 de Feb. de 2021
I wish this code was commented. I understand the general idea, but would like to see the logic flow of whoever wrote it.

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Olel Arem el 1 de Mayo de 2020
Editada: Olel Arem el 1 de Mayo de 2020
function distance=get_distance(city_1,city_2)
n=0;m=0;
for ii=1:size(name,2)
if (strcmp(city_1,name(ii,1)))
n=ii;
end
end
for jj=1:size(name,1)
if (strcmp(city_2,name(1,jj)))
m=jj;
end
end
if(n==0 && m==0 && n==1&&m==1)
distance =-1;
elseif (n>0&&m>0)
distance=value(n-1,m-1);
else
distance=-1;
end
##### 2 comentariosMostrar NingunoOcultar Ninguno
Syed Zubair shah el 16 de Mzo. de 2022
if(n==0 && m==0 && n==1&&m==1)
can you explain why we use this line and kindly explain it
Rik el 16 de Mzo. de 2022
That will never be true. n can't be 0 and 1 at the same time. Why this uncommented block of code ever received an upvote is not clear to me.

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Taif Ahmed BIpul el 28 de Mayo de 2020
function distance=get_distance(A,B)
p=strcmp(All,A);
q=strcmp(All,B);
r=sum(p(:));
s=sum(q(:));
if ~(r==2&&s==2)
distance=-1;
return
end
a=find(p==1);
b=find(q==1);
distance=All{(a(1)),(b(1))};
##### 2 comentariosMostrar NingunoOcultar Ninguno
Nada Hussein el 20 de Jul. de 2020
Walter Roberson el 20 de Jul. de 2020
The ==2 does not make sense to me; it would make sense to me if it were ==1 meaning that exactly one column matched.
Oh wait... the Raw (third) output has the names in the first row and in the first column. The person who wrote the above code assumes that each name will appear exactly once in the header row and once in the header column, for a total of two appearances: that is why the 2. The person also assumes that the order is exactly the same between the rows and columns.
Distance matrices should not be assumed to be symmetric. I would not recommend this version of the code.

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UJJWAL Padha el 11 de Jun. de 2020
function distance = get_distance(x,y)
k=-1;
[r c] = size(all)
for i = 1:r
for j = 1:c
if i==1 && j==1
continue;
else
if strcmp(x,all(i,1))==1 && strcmp(y,all(1,j))==1
k= all{i,j};
end
end
end
end
distance = k;
end
##### 2 comentariosMostrar NingunoOcultar Ninguno
Sumit Naza el 1 de Sept. de 2020
this doesn't return Distance=-1
Rik el 1 de Sept. de 2020
It turns out you can't reliably cheat off this page, because some solutions have bugs or flaws. If that weren't the case I would probably be a lot more active in deleting answers.

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Ankit singh chauhan el 29 de Nov. de 2020
Editada: Rik el 29 de Nov. de 2020
g=strcmp(raw,city1)
[r1,c1]=find(s==1)
[r2,c2]=find(g==2)
distance=raw{r1,r2}
catch
distance=-1
end
##### 1 comentarioMostrar -1 comentarios más antiguosOcultar -1 comentarios más antiguos
Rik el 29 de Nov. de 2020
Still the same question: why did you post this? What does it teach?

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Gokul surya Subramanian el 17 de Abr. de 2019
Editada: Rik el 2 de Jul. de 2019
function distance = get_distance(a,b)
for i=2:size(raw,1)
if strcmp(text{i,1}, a)
break
end
end
if i>=size(raw,1)
distance=-1;
else
for j=2:size(raw,2)
if strcmp(text{1,j}, b)
distance=raw{i,j};
break
end
end
if j>=size(raw,2)
distance = -1;
end
end
##### 13 comentariosMostrar 11 comentarios más antiguosOcultar 11 comentarios más antiguos
Jobin Geevarghese Thampi el 17 de Feb. de 2021
this one also 'if string(A)==string(txt{1,i})' why 1?
Walter Roberson el 17 de Feb. de 2021
For this particular homework problem, the reference data has been defined to be stored in a xlsx file that has the format
<empty> <cityname1> <cityname2> <cityname3> ...
<cityname1> distance11 distance12 distance13 ...
<cityname2> distance21 distance22 distance23 ...
where the <cityname> are text such as 'Los Vegas, Nevada' and 'Wawa, Ontario', and the distances are numeric.
When you use xlsread on the file and ask for the second output, the output will be a cell array of character vectors, with the character vectors being present where the original data had text, and being empty where the original data had numbers. So it might look something like
txt = {
[], 'LA', 'Wawa', 'Lima'
'LA' [] [] []
'Wawa' [] [] []
'Lima' [] [] []
}
When you use txt{1,i} you would therefore be accessing the [] at the beginning, or one of the city names, 'LA', 'Wawa', 'Lima' -- you would be reading out of row #1 from the txt cell array. txt{ROWNUMBER, COLUMNNUMBER} is the general form.
Using string() on a character vector converts it from being a character vector to being a scalar "string" object. So the line
if string(A)==string(txt{1,i})
converts character vector inside A to a string() object; and then extracts the content of column #i from row 1 of the cell array named txt and converts that content into a string() object. Then the line uses == between the string objects.
The reason someone would do that is that == is defined between string objects to return true of the strings have the same content, and false if the strings do not have the same content, with false being returned if they are different because they have different lengths. So string('LA') == string('Wawa') is perfectly good code that will not have a problem.
But == is not defined between character vectors in the same way, In particular, == between character vectors will fail if they both have more than one character and the lengths do not match. 'LA'=='Wawa' would fail complaining that the array dimensions do not agree (meaning that the lengths are different.) To compare character vectors taking into account they might be different lengths, use strcmp(), as in strcmp('LA', 'Wawa')

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function distance = get_distance(a,b)
for i=2:size(raw,1)
if strcmp(text{i,1}, a)
break
end
end
if i>=size(raw,1)
distance=-1;
else
for j=2:size(raw,2)
if strcmp(text{1,j}, b)
distance=raw{i,j};
break
end
end
if j>=size(raw,2)
distance = -1;
end
end
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Alan Chacko el 13 de Mayo de 2020
function d = get_distance(c1,c2)
[r,c] = size(city);
row = city(1:end,1);
col = city(1,1:end);
ccr=sort(contains(row(2:end),c1));
ccc=sort(contains(col(2:end),c2));
if ccr'==ccc
ir = find(strcmp(row,c1));
ic = find(strcmp(col,c2));
d = city{ir,ic};
else
d=-1;
end
##### 5 comentariosMostrar 3 comentarios más antiguosOcultar 3 comentarios más antiguos
Jagadeesh Korukonda el 31 de Mayo de 2020
this errors are coming
Walter Roberson el 31 de Mayo de 2020
What happens when you use the debugger to trace the flow of your code?

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Timothy Simon Thomas el 21 de Mayo de 2020
function distance=get_distance(L1,L2)
i=1;j=1;
[R C]=size(n);
while(~(strcmp(L1,r(1,i))) && i<=R)
i=i+1;
end
while(~(strcmp(L2,r(j,1)))&& j<=C)
j=j+1;
end
j=j-1;i=i-1;
if(~(strcmp(L1,r(1,i+1))) || ~(strcmp(L2,r(j+1,1))))
distance=-1;
else
distance=n(i,j);
end
end
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Ujjawal Barnwal el 7 de Jun. de 2020
function distance=get_distance(c1,c2)
a=0;b=0;
for ii=2:337
if strcmp(txt{1,ii},c1)
a=ii;
elseif strcmp(txt{1,ii},c2)
b=ii;
end
end
if a && b
distance=num(a-1,b-1);
else
distance=-1;
end
##### 1 comentarioMostrar -1 comentarios más antiguosOcultar -1 comentarios más antiguos
Walter Roberson el 7 de Jun. de 2020
Why 337?
Your code assumes that Distances contains data of a particular size. It also assumes that the number of rows and columns is the same. It further assumes that there is never a case where the two different cities happen to occur at the same row and column number. For example,
* apple orange grapefruit
orange 2 0 3
grapefruit 1 3 0
apple 0 2 1
Your code would fail for (say) orange, grapefruit because it assumes that when it finds orange in column 3, that it is not possible to also happen to find grapefruit in row 3.

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Vishesh Haria el 7 de Jun. de 2020
function distance=get_distance(a,b)
row=raw(1,:);
col=raw(:,1);
for ii=2:length(row)
if strcmp(row(ii),a)
mii=ii;
break;
end
end
for jj=2:length(col)
if strcmp(col(jj),b)
njj=jj;
break;
end
end
if(njj > 0 && mii > 0)
distance = raw{mii,njj};
elseif(njj == 1 && mii == 1)
distance = -1;
elseif(njj == 0 && mii == 0)
distance = -1;
else
distance=-1;
end
end
Error:
distance = get_distance('g, WA','Miagmi, FL')
Unrecognized function or variable 'njj'.
Error in get_distance (line 19)
if(njj > 0 && mii > 0)
Help me understand this error.
##### 1 comentarioMostrar -1 comentarios más antiguosOcultar -1 comentarios más antiguos

I think you might remove two elif condition commands and set default "mii" and "njj" as 0, then it could work.

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Md Nazmus Sakib el 20 de Jun. de 2020
function y = get_distance(city_1,city_2)
global raw;
%fetching cities in rows
r_city = {};
for i = 1:337
r_city{1,i} = raw{1,i};
end
%fetching cities in columns
c_city = {};
for j = 1:337
c_city{1,j} = raw{j,1};
end
%searching city_1
search_c1 = strcmp(c_city,city_1);
%searching row
for ii = 1:337
if (search_c1(1,ii) == 1)
break
else
ii = 1;%if the city is not found ii will give 1
end
end
%searching city_2
search_c2 = strcmp(r_city,city_2);
%searching column
for jj = 1:337
if (search_c2(1,jj) == 1)
break
else
jj = 1;%if the city is not found jj will give 1
end
end
if ((ii == 1) || (jj == 1)) % if the city is not found
y = -1;
else
y = raw{ii,jj}(1,1);
end
end
##### 2 comentariosMostrar NingunoOcultar Ninguno
Walter Roberson el 20 de Jun. de 2020
What will you do when the Distances.xlsx file does not have exactly 337 rows and columns ?
Md Nazmus Sakib el 21 de Jun. de 2020
Thanks, I think I'll first measure the size or length of 'raw'.

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M NAGA JAYANTH AVADHANI el 28 de Jul. de 2020
This works perfectly.
function distance = get_distance(city1,city2)
row = raw(1,:);
col = raw(:,1);
mi =0;mj =0;
for i = 2:length(row)
if strcmp(row(i),city1)
mi = i;
end
end
for j = 2:length(col)
if strcmp(col(j),city2)
mj = j;
end
end
if mi> 1 && mj>1
distance = raw{mi,mj};
else
distance = -1;
end
end
##### 3 comentariosMostrar 1 comentario más antiguoOcultar 1 comentario más antiguo
Rik el 14 de Ag. de 2020
Look through the rest of the code. Where are values for mi and mj set? Only inside if statements. Is it guaranteed that those lines are reached? What would be the consequence of those variables not being set?
THIERNO AMADOU MOUCTAR BALDE el 30 de Dic. de 2020
thanks sir

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Capulus_love el 12 de Ag. de 2020
Editada: Capulus_love el 12 de Ag. de 2020
function distance = get_distance(a,b)
col = excel(1,:);
row = excel(:,1);
x=size(col)
y=size(row)
col_count = 1;
row_count = 1;
for i = 2 : x(2)+1
col_count = col_count + 1;
if contains(col{i},a) == 1
break
end
end
for j = 2 : y(1)+1
row_count = row_count + 1;
if contains(row{j},b) == 1
break
end
end
if (col_count > 337) || (row_count > 337)
distance = -1
else
distance = excel{row_count,col_count}
end
end
% why Non-existent city is not solved...???
##### 3 comentariosMostrar 1 comentario más antiguoOcultar 1 comentario más antiguo
Rik el 12 de Ag. de 2020
Where are you checking if a city exists in the list? What happens on each line if that happens?
Walter Roberson el 12 de Ag. de 2020
if (col_count > 337) || (row_count > 337)
What would happen if they changed the data file to one that had (for example) 500 cities?

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Yan Li el 4 de Sept. de 2020
function distance = get_distance (ct1, ct2)
f_row = raw(1,:);
f_col = raw(:,1);
flag = false;
distance = -1;
for n=1:length(f_row)
for m=1:length(f_col)
if string(f_row(n)) == ct1 && string(f_col(m)) == ct2
flag = true
distance = raw{n,m};
end
end
end
end
##### 2 comentariosMostrar NingunoOcultar Ninguno
Yan Li el 4 de Sept. de 2020
THE CODE PASSED ALL TESTS, MIGHT NOT BE THE SMARTEST, BUT A WORKING ONE.
Rik el 4 de Sept. de 2020
Surprisingly enough this works.
string({'foo'})=='foo'
Why did you decide to post this? What does it teach?
Also, why are you setting a flag, but not returning it or using it anywhere?

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Ahmed Saleh el 28 de Mzo. de 2021
Editada: Ahmed Saleh el 28 de Mzo. de 2021
function distance = get_distance(city1,city2)
num1=0;
num2=0;
s=size(distances);
for i=2:s(1)
logic=strcmp(city1,distances{i,1});
if logic== true
num1=i;
break
end
end
for j=2:s(2)
logic2 = strcmp(city2,distances{1,j});
if logic2 == true
num2=j;
break
end
end
if num1==0 || num2==0
distance=-1;
return
end
distance=distances{num1,num2};
end
##### 7 comentariosMostrar 5 comentarios más antiguosOcultar 5 comentarios más antiguos
Rik el 29 de Mzo. de 2021
You mean that one? You can use it to attract the attention of high reputation users and site administrators to solve a particular issue (e.g. if a post should be deleted or a thread should be closed).
Also, strcmp doesn't just return 1 or 0, it returns true or false. And it doesn't always return 1 value.
To refrase Walter's second question: when is false equal to true or is true not equal to true?
Use the debugger to execute your code line by line.
Ahmed Saleh el 30 de Mzo. de 2021
ok, thank you

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Abhijeet Singh el 14 de Mayo de 2021
Editada: Abhijeet Singh el 14 de Mayo de 2021
function distance = get_distance(x,y)
a = everything(1:size(everything,1),1);
b = everything(1,1:size(everything,2));
for j = 1:size(everything,1)
l=0;
if strcmp(a(j,1),x)
l=j;
break
end
end
for i = 1:size(everything,2)
k=0;
if strcmp( b(1,i),y)
k=i;
break
end
end
if k ~= 0 && l ~= 0
s = everything(l,k);
distance = s{1};
else
distance = -1;
end
end
##### 3 comentariosMostrar 1 comentario más antiguoOcultar 1 comentario más antiguo
Abhijeet Singh el 15 de Mayo de 2021
@RikIt is another way to solve the given problem! And it will work even if we add few details in the xlx file.
Rik el 15 de Mayo de 2021
What would you say is the key difference between your solution and the one above this one?
If you want to educate: comments are a great way to explain what your code is doing.
Also:
a = everything(1:size(everything,1),1);
b = everything(1,1:size(everything,2));
%is equivalent to this:
a = everything(:,1);
b = everything(1,:);

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Silvana Castillo el 3 de Jun. de 2021
function distance = get_distance(c1,c2);
% reads excel file in just everything
% find would give index of c1 readinf first column
a = find(strcmp(everything(1,1:end),c1))
% find would give index of c2 reading first row
% strcmp = are equals two strings inputs?
b = find(strcmp(everything(1:end,1),c2))
% if any c1 or c2 do not exist
if isempty(a) || isempty(b)
distance = -1
else
% converts from cell class to matrix or double
%the distance value based on index
distance = cell2mat(everything(a,b))
end
##### 0 comentariosMostrar -2 comentarios más antiguosOcultar -2 comentarios más antiguos

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Milad Mehrnia el 31 de Oct. de 2021
function distance = get_distance(a,b)
x = 0;y = 0;
for i = 2:lenghth(txt)
if strcmp(txt{1,i},a)
x = i;break; % It's better to use break, Because it reduces the running time significantly
end
end
for j = 2:height(txt) % It's better to use a seperated for function for j, Because it reduces the running time significantly too
if strcmp(txt{j,1},b)
y = j;break;
end
end
if ~x || ~y
distance = -1;
else
distance = num(x-1,y-1);
end
##### 2 comentariosMostrar NingunoOcultar Ninguno
Rik el 1 de Nov. de 2021
You are on the right track. I would suggest looking up the numel and size functions (as replacement for height and length, which you misspelled).
I would also suggest looking up ismember, which can further increase performance.
Milad Mehrnia el 1 de Nov. de 2021
As we have the matrices on the memory, you are right and ismember is better than for. After your comment I tried it and the result is awesome. It brakes the time to half.
Really thank you

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Zia Ur Rehman el 30 de Ag. de 2022
Hi folks,
plz check my code and plz tell me if I can improve this.
function distance = get_distance(a,b)
[~, ~, data] = xlsread('Distances.xlsx'); %reading the file and having its full data that is by default raw data in data variable on 3rd aurgument
z = size(data); % Calculating the size as we need to traverse both first coloumn and first row
c = z(1,1); % c = no. of rows
d = z(1,2); % d = no. of coloumn
for i = 2:c % as (1,1) of file is empty so starting from 2 to the length of rows and coloumns
e = strcmp(data{1,i},a); % checking through first row and compare with a
if e == true % if we find the matching then record its index in f and stop the loop through 'break'.
f = i;
break;
end
end
for j = 2:d
k = strcmp(data{j,1},b); % checking through first coloumn and compare with b
if k == true % if we find the matching then record its index in l and stop the loop through 'break'.
l = j;
break;
end
end
if e==true && k==true % if both are true then show the distance at that index(f,l) otherwisr distance = -1
distance = data{f,l};
else
distance = -1;
end
##### 4 comentariosMostrar 2 comentarios más antiguosOcultar 2 comentarios más antiguos
Walter Roberson el 30 de Ag. de 2022
ismember() is easier than looping
Zia Ur Rehman el 30 de Ag. de 2022
ok, I will check how this builtin function works.

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Pascal el 15 de Jun. de 2023
I got this solution but the last bit of code seems rather plump, do you have suggestions to improve the code?
function [distance] = get_distance(c1,c2)
row1 = raw(1,2:end);
col1 = raw(2:end,1);
ind1 = find(ismember(row1,c1));
ind2 = find(ismember(col1,c2));
if isempty(ind1) || isempty(ind2)
distance = -1;
else
dis = raw(2:end,2:end);
d = dis(ind1,ind2);
distance = cell2mat(d);
end
##### 0 comentariosMostrar -2 comentarios más antiguosOcultar -2 comentarios más antiguos

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