Sorting imported data into a structure array

Question

Sam Zipper 2011-10-11

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/18055-sorting-imported-data-into-a-structure-array

Hi everyone-

I have a question about organizing some data I've collected and I couldn't find anything similar on here. Here is a simplified version of my problem:

I have a structure array (named 'hydro'). This structure is for three research sites ('WAU_Forest', 'WAU_Wetland', and 'CHE_Forest'). At each one of these sites, there is a structure for each of the three species of plants (different at each site). For example, hydro(1).spec(1) would be a Hickory at WAU_Forest. For each plant, I'm measuring temperature and transpiration. Now, let's say I have collected some data that's in .csv format:

Site,Species,Temp,Transpiration

WAU_Wetland,Cattail,20,100

WAU_Wetland,Cattail,25,150

WAU_Forest,Hickory,20,300

WAU_Forest,Hickory,20,350

CHE_Forest,Hickory,30,450

CHE_Forest,Boxelder,30,400

CHE_Forest,Hickory,32,200

etc.

My goal is to have MATLAB open a file, extract the data, use the first two columns (site and species) to sort the data, then put the last two columns (temp and transp) into a data table at that section of the structure.

It ends up being a few thousand data points in a couple dozen Excel files - some of which have all the sites, some of which have only one or two - so I'd rather not do this by hand. And, there's actually 15 sites, and a lot more data collected than just temperature and transpiration. I know how to import the data, but sorting it based on the text of the first two columns has me stumped. Any help would be much appreciated.

Thanks in advance for your help,

-Sam

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Hossein 2011-10-11

let say that you put all of your excel files into one file or you just run the program for one file and then resume it to the next file. then

for i=1:number_of_rows_in_excel_file

switch z(i,1)

case 'WAU_Wetland'

if strcmp(z(i,2),'Hickory')

hydro(1).spec(1).Temp(k)=z(i,3);

hydro(1).spec(1).Transpiration(k)=z(i,4);

k=k+1;

if strcmp (z(i,2),'Cattail'

hydro(1).spec(2)

case 'CHE_Forest'

if strcmp(z(i,2),'Cattail')

hydro(2).spec(2)

and ...

I am sure you could come up with a more efficient code, but I think all you need is to compare first two column with a strings defining sites and species. Instead of index k you will probably need 9 index so it could be as well k(i,j).

-Hossein

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Answer 1

Fangjun Jiang 2011-10-11

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https://ww2.mathworks.cn/matlabcentral/answers/18055-sorting-imported-data-into-a-structure-array#answer_24324

在 MATLAB Online 中打开

I don't fully understand the structure of your struct array, but for sorting, you can reference the following example:

>> [Num,Txt]=xlsread('test.csv')
Num =
    20   100
    25   150
    20   300
    20   350
    30   450
    30   400
    32   200
Txt = 
    'DataWAU_Wetland'    'Cattail' 
    'WAU_Wetland'        'Cattail' 
    'WAU_Forest'         'Hickory' 
    'WAU_Forest'         'Hickory' 
    'CHE_Forest'         'Hickory' 
    'CHE_Forest'         'Boxelder'
    'CHE_Forest'         'Hickory' 
>> [SortedTxt,index]=sortrows(Txt)
SortedTxt = 
    'CHE_Forest'         'Boxelder'
    'CHE_Forest'         'Hickory' 
    'CHE_Forest'         'Hickory' 
    'DataWAU_Wetland'    'Cattail' 
    'WAU_Forest'         'Hickory' 
    'WAU_Forest'         'Hickory' 
    'WAU_Wetland'        'Cattail' 
index =
     6
     5
     7
     1
     3
     4
     2
>> SortedNum=Num(index,:)
SortedNum =
    30   400
    30   450
    32   200
    20   100
    20   300
    20   350
    25   150