I want to know the best way of importing both number and non-numeric data (which is string in the present case) from an excel file into MATLAB? By best (or better) way, I mean all the data together in a variable (or data structure).
First, I tried uiopen(filename) function which opens a wizard and from there, I can import the data into a MATLAB variable. However, problem here is that it replaces all the non-numeric data with zeros which is not required. I later on, found that this function calls another function, named xlsread(filename), which is another way (actual way) of importing excel file.
Second (last) way that I tried (which seems to be better) is to use function called importdata(filename) which imports both numeric and non-numeric data into separate structure variables.
However, I am wondering if there exists some other way(s) to import everything into a single variable or data structure?
xlsread is the correct way to import data from Excel spreadsheets,both numeric and non-numeric data. Check the documentation:
[num,txt,raw] = xlsread(___) additionally returns the text fields in
cell array txt, and the unprocessed data (numbers and text) in cell
array raw using any of the input arguments in the previous syntaxes.
If xlRange is specified, leading blank rows and columns in the
worksheet that precede rows and columns with data are returned in raw.
Related
I have some data I imported from a excel spreadsheet as a csv. I created a dataframe using Pandas, and want to change a specific column. The column contains strings such as "5.15.1.0.0". I want to change these strings to floats like "5.15100".
So far I've tried using the method "replace" to change every instance in that column:
df['Fix versions'].replace("5.15.1.0.0", 5.15.1.0.0)
this however does not work. When I reprint the dataframe after the replace methods are called it shows me the same dataframe where no changes are made. Is it not possible to change a string to a float using replace? If not does anyone know another way to do this?
I could parse each string and remove the "." but I'd prefer not to do it this way as some of the strings represent numbers of different lengths and decimal place values.
Adding the parameter "inplace" which default is false. Changing this to true will change the dataframe in place, which can be type casted.
df['Fix versions'].replace(to_replace="5.15.1.0.0", value="5.15100", inplace=True)
I am retrieving data through Power Query from an Oracle DB live to an Excel workbook. In PQ, under the "Transform" tab, there is a function to change the data type of a column, that I use to get all the decimal numbers displayed. In the M-code the function is called TransformColumnTypes. However I have some strings in the data that I cannot change to decimal number and produce an error. Is there a way to exclude these? Because the function takes the whole column at the moment.
Before applying function
Function producing error
Code
I don't think so. If you have multiple types within a column, text is the only one that doesn't produce errors.
But if it is only the first row like in your image, promoting it to header before setting the column type will fix the issue.
thanks for taking a look at my question.
I'm having a peculiar issue importing an xlsx file into MATLAB R2016a (Mac OS X) , more specifically importing dates.
I am using the below code to import my bank statement history from the Worksheet 'Past' in the xlsx file 'bank_statements.xlsx'. A snippet of column 1 with the dates in dd/mm/yyyy format is also included.
[ndata, text, data] = xlsread('bank_statements.xlsx','Past');
My understanding is that MATLAB uses filters to distinguish between text and numeric data with these being represented in the 'text' and 'data' arrays respectively whilst 'ndata' is a cell array with everything included. Previously, when running the script on MATLAB 2015a (Windows) the dates from column 1 were treated as strings and populated in the 'text' array, whilst on MATLAB 2016a (Mac OS X) column 1 of the text array is blank. I assumed this was because updates had been made to how the xlsread function interprets date information.
Here's the strange part. Whilst inspecting the text array through the Variables window and referencing in the Command Window shows text(2,1) to be empty, performing the datenum function on this "empty" cell successfully gives the date in a numbered format:
Whilst I can solve this issue by using the ndata array (or ignoring the fact that the above doesn't make sense to me) I'd really like to understand what is happening here and whilst a seemingly empty cell can actually be holding information which operations can be performed on.
Best regards,
Jim
I was able to replicate your problem and although I can't answer the intricacies of what is happening, I could offer a suggestion. I was only able to replicate it when I was converting a string of non-date text, which leads me to believe that there might be an issue with the way the data was imported.
Instead of:
[ndata,text,data] = xlsread('bank_statements.xlsx','Past');
maybe try and add in the #convertSpreadsheetDates function if you have it, along with the range of values you want to import, i.e.
[ndata,text,data] = xlsread('bank_statements.xlsx','Past','A2:A100','',#convertSpreadsheetDates);
Probably not what you are looking for but it might help!
I'm looking to write a script for MATLAB that will import data from a csv file which has a first row containing string headers and the data in each of those columns is either string, date or numeric.
I want to then be able to filter the data in MATLAB according to instances of a particular string and number combination.
Any help appreciated!
Cheers!
I would recommend you to start with reading MATLAB documentation.
[num,txt,raw] = xlsread('myExample.xlsx')
Reads numeric, text and combined data, so, if your data is combined, then you need the cell array raw. After that, you do whatever you want with your cell array (Additional information is not provided since OP did not provide any specific information about the way the data would be filtered)
Try using readtable function in MATLAB.
It correctly imports csv file with header and mixed data type.
xlsread was imported by mixed csv file very incorrectly repeating the some rows while maintaining the same total rows.
I got this after searching for a long time:
MATLAB Central Question/Answer
I have a matrix where the first column contains dates and the first row contains maturities which are alpha/numeric (e.g. 16year).
The rest of the cells contain the rates for each day, which are double precision numbers.
Now I believe xlsread() can only handle numeric data so I think I will need something else or a combination of functions?
I would like to be able to read the table from excel into MATLAB as one array or perhaps a struct() so that I can keep all the data together.
The other problem is that some of the rates are given as '#N/A'. I want the cells where these values are stored to be kept but would like to change the value to blank=" ".
What is the best way to do this? Can it be done as part of the input process?
Well, from looking at matlab reference for xlsread you can use the format
[num,txt,raw] = xlsread(FILENAME)
and then you will have in num a matrix of your data, in txt the unreadable data, i.e. your text headers, and in raw you will have all of your data unprocessed. (including the text headers).
So I guess you could use the raw array, or a combination of the num and txt.
For your other problem, if your rates are 'pulled' from some other source, you can use
=IFERROR(RATE DATA,"")
and then there will be a blank instead of the error code #N\A.
Another solution (only for Windows) would be to use xlsread() format which allows running a function on your imported data,
[num,txt,raw,custom] = xlsread(filename,sheet,xlRange,'',functionHandler)
and let the function replace the NaN values with blank spots. (and you will have your output in the custom array)