使用R语言SIAR包绘制d15N-d13C双图时遇报错，寻求解决方案

Hey there, let's tackle this SIAR error head-on—it's a super common issue tied to data formatting, so we can work through it step by step. The error is telling you loud and clear that your source (or possibly consumer) isotope data isn't in pure numeric format, which the SIAR Dirichlet model requires to run calculations.

1. First, diagnose your data structure #

Start by checking the data types of your DataSISource and DataSIConsumer objects. Run these commands in R:

# Check source data structure
str(DataSISource)
# Check consumer data structure
str(DataSIConsumer)

Look specifically at your d13C and d15N columns—they must be labeled as numeric. If you see character or factor instead, that's the root problem.

2. Clean and convert non-numeric columns #

If you find non-numeric isotope columns, it's usually because your raw data has hidden issues: stray spaces, letters, special characters, or even misformatted headers. Fix this by converting the columns to numeric, then check for missing values that pop up (these flag invalid entries):

# Convert source data columns to numeric
DataSISource$d13C <- as.numeric(DataSISource$d13C)
DataSISource$d15N <- as.numeric(DataSISource$d15N)

# Convert consumer data columns to numeric
DataSIConsumer$d13C <- as.numeric(DataSIConsumer$d13C)
DataSIConsumer$d15N <- as.numeric(DataSIConsumer$d15N)

# Check for NA values (these mean invalid entries were present)
sum(is.na(DataSISource))
sum(is.na(DataSIConsumer))

If you get NA values, go back to your original data file (like a CSV) and delete any non-numeric content in those isotope columns.

3. Verify your data matches SIAR's required format #

Double-check that your data aligns with the structure outlined in the SIAR guide:

• Source data: First column is source names (character/factor), followed by numeric columns for isotope means, standard deviations, and sample sizes (e.g., d13C_mean, d13C_sd, d13C_n, d15N_mean, d15N_sd, d15N_n). No missing values allowed in these numeric columns.
• Consumer data: Each row is a single sample, with numeric columns for d13C and d15N. Any grouping columns should be character/factor, not numeric.

4. Test with example data to rule out package issues #

To confirm the problem is with your data (not the SIAR package itself), run the model with SIAR's built-in example data (if available):

# Load example data (check SIAR's documentation for exact object names)
data(siar_example)
# Run model with example data
test_model <- siarmcmcdirichletv4(siar_example$consumer, siar_example$source, corrections=0, concdep=0, iterations=500000, burnin=50000)

If this runs without errors, you know your custom data has formatting issues—go back to steps 1-3 to refine it.

5. Quick extra checks #

• Make sure your corrections and concdep parameters are numeric (your 0 values are fine here, but avoid passing character strings by accident).
• When importing data (e.g., with read.csv()), use stringsAsFactors=FALSE to prevent R from converting numeric columns to factors unintentionally.

内容的提问来源于stack exchange，提问作者Lindsay Cox