Splitting up large amount of data into smaller tables based on one coloumn

Question

pillowheaded 2019-2-12

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/444553-splitting-up-large-amount-of-data-into-smaller-tables-based-on-one-coloumn

评论： Peter Perkins 2019-3-11

clear all; close all;

% x = x, y = y, r= raman shift, i = intensity

[x] = textread('rawData.txt');

y=size(x);

rv=length(x);% rv = raman shift value

B1=zeros(rv,4);

for c=1:1:rv-1;

for i=1:4;

if x(c,3)>x(c+1,3)

B1(c,i)=x(c,i);

B1=B1+1;

elseif x(c,3)<x(c+1,3);

B1(c,i)=x(c,i);

B1=B1+1;

end

Hi all this is my current code, i have a very large data set comprised of 4 coloumns, and i need to seperate it when a value in the third coloumn is smaller than the next value. The number of values between this happening is not consistent, but i need to seperate it out into lots of tables of the 4 coloumns

Any help would be greatly appreciated!!

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Bob Thompson 2019-2-12

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/444553-splitting-up-large-amount-of-data-into-smaller-tables-based-on-one-coloumn#answer_360690

编辑：Bob Thompson 2019-2-12

Hmm, I think I kind of understand what you are trying to do. Let me know if this works.

mark = 1;
cll = 1;
for i = 2:size(x,1)
    if x(i,3) > x(i-1,3);
        tests{cll} = x(mark:i,:);
        cll = cll + 1;
        mark = i;
    end
end

This should look for the different breaks, and record the different data sets into cells in 'tests'.

2 个评论
显示无隐藏无

pillowheaded 2019-2-13

Thank you so much that has done exactly what i need it to!

pillowheaded 2019-2-22

Hi

I have been using the code you wrote and realised that it misses out the last block of data is there anyway to add additional lines of code to ensure it copies all the data?

thank you for your help

请先登录，再进行评论。

Answer 2

Peter Perkins 2019-2-25

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/444553-splitting-up-large-amount-of-data-into-smaller-tables-based-on-one-coloumn#answer_362634

在 MATLAB Online 中打开

You have not said why you want to do that, but in general, you DON'T want to split one table up into lots of tables. You will usually find that less convenient than just haivng an indicator variable in your one table.

In any case, to create that indicator, you don't need loops. Find the changepoints, and cumsum:

>> t = array2table(rand(10,3))
t =
  10×3 table
      Var1        Var2        Var3  
    _________    _______    ________
      0.10665    0.43141     0.85303
       0.9619    0.91065     0.62206
    0.0046342    0.18185     0.35095
      0.77491     0.2638     0.51325
       0.8173    0.14554     0.40181
      0.86869    0.13607    0.075967
     0.084436    0.86929     0.23992
      0.39978     0.5797     0.12332
      0.25987    0.54986     0.18391
      0.80007    0.14495     0.23995
>> t.Indicator = cumsum([true; t.Var3(2:end) > t.Var3(1:end-1)])
t =
  10×4 table
      Var1        Var2        Var3      Indicator
    _________    _______    ________    _________
      0.10665    0.43141     0.85303        1    
       0.9619    0.91065     0.62206        1    
    0.0046342    0.18185     0.35095        1    
      0.77491     0.2638     0.51325        2    
       0.8173    0.14554     0.40181        2    
      0.86869    0.13607    0.075967        2    
     0.084436    0.86929     0.23992        3    
      0.39978     0.5797     0.12332        3    
      0.25987    0.54986     0.18391        4    
      0.80007    0.14495     0.23995        5    

2 个评论
显示无隐藏无

pillowheaded 2019-2-27

Hi thank you for your answer,

the reason i want to do this is my data is a series of scans taken at various points but instead of the data being individual files the output is they are all stacked into one giant table with 4 coloumns.

i see what you have done and i like it but it is more benifical to me to have them split up as i then go on to fit peaks as each set of data is a spectre.

how would i use this code to then divide up the data?

Peter Perkins 2019-3-11

在 MATLAB Online 中打开

n = 5;
c = cell(n,1);
for i = 1:n
    c{i} = t(t.Indicator==i,1:3);
end

请先登录，再进行评论。

Splitting up large amount of data into smaller tables based on one coloumn

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

回答（2 个）

2 个评论
显示无隐藏无

2 个评论
显示无隐藏无

另请参阅

类别

标签

Community Treasure Hunt

Splitting up large amount of data into smaller tables based on one coloumn

0 个评论 显示 -2更早的评论隐藏 -2更早的评论

回答（2 个）

2 个评论 显示 无隐藏 无

2 个评论 显示 无隐藏 无

另请参阅

类别

标签

Community Treasure Hunt

WeChat

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

2 个评论
显示无隐藏无

2 个评论
显示无隐藏无