Importing a CSV does not include all columns

ParaView Support
1

I have a .csv file with three columns and 441 rows. It is completely numerical. This csv was generated by Kenneth Moreland in his excellent answer to 2D contour from .csv as a test file.

When trying to import this into paraview, I only get two of the three columns, plus a column called “row ID”.

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This seems very odd, as in the answer given on the previous page, the third column was needed to generate a colour map.

Any ideas on how to get all three columns? I am using the default CSV reader to open this.

2

Add a heading to each column [ e.g. X, Y, Z ] and then import with CSV reader.

1 Like
3

Thank you, this fixed the issue!

4

Might just add as I had the same issue recently:
Make sure the last data line in the CSV file does not have a trailing whitespace. This also leads to Paraview not showing the last column.

1 Like
5

This is an excellent tip, definitely something to watch out for.

I’ll also add that python is great for avoiding any potential issues with a weird csv file. Pandas makes filtering out things you don’t want - excess headers, comments, bad data, really easy.

For example, I use the following code for one particular file I get from another program which loves to add comments to my data, and uses -1 instead of NaN:

import numpy as np
import pandas as pd

df = pd.read_csv(r"C:\Users\User\yourdata.txt",
                       comment='#',delim_whitespace=True, header=None,
                      )
df.columns =['qx', 'qz', 'counts']  #these are the x, y, and z labels for my data, which is a 2D XRD scan if you're curious.
df['counts'] = df['counts'].mask(df.counts < 0) #change negative values to NaN

for series_name, series in df.items():
    name = series_name
    array = series.to_numpy()
    output.RowData.append(array, name)

This is probably my favourite method so far, I don’t love the default CSV reader. But when I’m following a tutorial I think it’s best that I don’t do anything fancy haha.

6

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Also, if the data doesn’t have headers, it helps to make sure that this box is not ticked!! A semi-obvious solution - I assumed that this wouldn’t case issues and that the first line of data would become a header, but it seems that wasn’t the case.