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'

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Abhishek singh
Abhishek singh 2019-4-17
回答： Pascal 2023-6-15
function distance = get_distance(x,y)
[~,~,raw] = xlsread('Distances.xlsx');
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.

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回答（22 个）

Arafat Roney
Arafat Roney 2020-5-6
function distance=get_distance(a,b)
[~,~,raw]=xlsread('Distances.xlsx');
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 个评论
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SOUMYAJIT MONDAL
SOUMYAJIT MONDAL 2021-8-20
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), ....

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Mati Somp
Mati Somp 2020-10-6
one more
function distance = get_distance(A,B)
[data txt] =xlsread('Distances.xlsx');
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
Olel Arem
Olel Arem 2020-5-1
编辑：Olel Arem 2020-5-1
function distance=get_distance(city_1,city_2)
n=0;m=0;
[value,name]=xlsread('Distances.xlsx');
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
Taif Ahmed BIpul
Taif Ahmed BIpul 2020-5-28
function distance=get_distance(A,B)
[~,~,All]=xlsread('Distances.xlsx');
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 个评论
Walter Roberson
Walter Roberson 2020-7-20
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
UJJWAL Padha 2020-6-11
function distance = get_distance(x,y)
k=-1;
[~,~,all] = xlsread('Distances.xlsx');
[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
Ankit singh chauhan
Ankit singh chauhan 2020-11-29
编辑：Rik 2020-11-29
function distance=get_distance(city1,city2) [~,~,raw]=xlsread('Distance.xlsx') try s=strcmp(raw,city2)
g=strcmp(raw,city1)
[r1,c1]=find(s==1)
[r2,c2]=find(g==2)
distance=raw{r1,r2}
catch
distance=-1
end
Gokul surya Subramanian
编辑：Rik 2019-7-2
function distance = get_distance(a,b)
[~,text,raw] = xlsread('Distances.xlsx');
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 个评论
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Walter Roberson
Walter Roberson 2021-2-17
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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Muhammad Sadiq
Muhammad Sadiq 2020-5-7
function distance = get_distance(a,b)
[~,text,raw] = xlsread('Distances.xlsx');
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
Alan Chacko
Alan Chacko 2020-5-13
function d = get_distance(c1,c2)
[~,~,city] = xlsread("Distances.xlsx");
[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
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Timothy Simon Thomas
function distance=get_distance(L1,L2)
[n,~,r]=xlsread('matlab_dist.xlsx');
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
Ujjawal Barnwal
Ujjawal Barnwal 2020-6-7
function distance=get_distance(c1,c2)
[num txt raw]=xlsread("Distances.xlsx");
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 个评论
Walter Roberson
Walter Roberson 2020-6-7
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
Vishesh Haria 2020-6-7
function distance=get_distance(a,b)
[~,~,raw]=xlsread('Distances.xlsx');
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.
Md Nazmus Sakib
Md Nazmus Sakib 2020-6-20
function y = get_distance(city_1,city_2)
global raw;
[~,~,raw] = xlsread('Distances.xlsx');
%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
M NAGA JAYANTH AVADHANI
编辑：M NAGA JAYANTH AVADHANI 2020-7-28
This works perfectly.
function distance = get_distance(city1,city2)
[~,~,raw] = xlsread('Distances.xlsx');
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 个评论
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Rik
Rik 2020-8-14
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?

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Capulus_love
Capulus_love 2020-8-12
编辑：Capulus_love 2020-8-12
function distance = get_distance(a,b)
[~,~,excel] = xlsread('Distances.xlsx');
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 个评论
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Walter Roberson
Walter Roberson 2020-8-12
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
Yan Li 2020-9-4
function distance = get_distance (ct1, ct2)
[~,~,raw]= xlsread("Distances.xlsx");
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 个评论
Rik
Rik 2020-9-4
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
Ahmed Saleh 2021-3-28
编辑：Ahmed Saleh 2021-3-28
function distance = get_distance(city1,city2)
[~,~,distances] = xlsread('Distances.xlsx');
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 个评论
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Rik
Rik 2021-3-29
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.

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Abhijeet Singh
Abhijeet Singh 2021-5-14
编辑：Abhijeet Singh 2021-5-14
function distance = get_distance(x,y)
[~,~,everything] = xlsread('Distances.xlsx');
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 个评论
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Rik
Rik 2021-5-15
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
Silvana Castillo 2021-6-3
function distance = get_distance(c1,c2);
% reads excel file in just everything
[~,~,everything] = xlsread('Distances.xlsx');
% 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
Milad Mehrnia
Milad Mehrnia 2021-10-31
function distance = get_distance(a,b)
[num,txt] = xlsread('Distances.xlsx');
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 个评论
Rik
Rik 2021-11-1
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
Milad Mehrnia 2021-11-1
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
Zia Ur Rehman 2022-8-30
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
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Pascal
Pascal 2023-6-15
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)
raw = readcell('Distances.xlsx');
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

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