text: user2005: I want to save a sparse and very large dgcMatrix onto disc. I read that it could be done with writeMM method. So, when I am trying to do that:
  writeMM(UMI_count, "/home/gene_count_filtered/filtered_dataset")
  
  Rstudio is giving me an error:
  Error in writeMM(UMI_count, "/home/gene_count_filtered/filtered_dataset") : 
  could not find function "writeMM"
  
  Ok, I read that this function is in the Matrix package. I installed it, but when I try loading it:
  library(Matrix)
  
  I am getting another error due to other libraries using Matrix already on the lower level, as I understand:
  Error in value[[3L]](cond) : 
  Package ‘Matrix’ version 1.2.11 cannot be unloaded:
  Error in unloadNamespace(package) : namespace ‘Matrix’ is imported by 
  ‘scran’, ‘scater’, ‘SummarizedExperiment’ so cannot be unloaded
  
  I also tried justwrite.matrix(UMI_count, "/home/nikita/filtered_dataset"), but got an error:
  
  Cholmod error 'out of memory' at file ../Core/cholmod_memory.c, line 147
  
  What could be the solution to the problem? I just need to somehow save a very large dgcMatrix on disc.
  
  user2005: Ultimately I just restarted Rstudio as Konrad Rudolph suggested, imported Matrix library, and then writeMM method worked just fine. However, rownames were converted into just numbers, but I needed to keep the gene names instead as it was in dgcMatrix, so after some search I found a different way of doing that from here: 
  http://www.sthda.com/english/wiki/saving-data-into-r-data-format-rds-and-rdata
  So, I just did save() (and then, to load back - load()) and the rownames are maintained like I wanted it to be. So, storing it now as .RData file.
  
original_text: 2005: <p>I want to save a sparse and very large <code>dgcMatrix</code> onto disc. I read that it could be done with <code>writeMM</code> method. So, when I am trying to do that:</p>
  
  <pre><code>writeMM(UMI_count, "/home/gene_count_filtered/filtered_dataset")
  </code></pre>
  
  <p><code>Rstudio</code> is giving me an error:</p>
  
  <pre><code>Error in writeMM(UMI_count, "/home/gene_count_filtered/filtered_dataset") : 
  could not find function "writeMM"
  </code></pre>
  
  <p>Ok, I read that this function is in the <code>Matrix</code> package. I installed it, but when I try loading it:</p>
  
  <pre><code>library(Matrix)
  </code></pre>
  
  <p>I am getting another error due to other libraries using <code>Matrix</code> already on the lower level, as I understand:</p>
  
  <pre><code>Error in value[[3L]](cond) : 
  Package ‘Matrix’ version 1.2.11 cannot be unloaded:
  Error in unloadNamespace(package) : namespace ‘Matrix’ is imported by 
  ‘scran’, ‘scater’, ‘SummarizedExperiment’ so cannot be unloaded
  </code></pre>
  
  <p>I also tried just<code>write.matrix(UMI_count, "/home/nikita/filtered_dataset")</code>, but got an error:</p>
  
  <blockquote>
    <p>Cholmod error 'out of memory' at file ../Core/cholmod_memory.c, line 147</p>
  </blockquote>
  
  <p>What could be the solution to the problem? I just need to somehow save a very large <code>dgcMatrix</code> on disc.</p>
   2005: <p>Ultimately I just restarted <code>Rstudio</code> as <code>Konrad Rudolph</code> suggested, imported <code>Matrix</code> library, and then <code>writeMM</code> method worked just fine. However, <code>rownames</code> were converted into just numbers, but I needed to keep the gene names instead as it was in <code>dgcMatrix</code>, so after some search I found a different way of doing that from here: </p>
  
  <p><a href="http://www.sthda.com/english/wiki/saving-data-into-r-data-format-rds-and-rdata" rel="nofollow noreferrer">http://www.sthda.com/english/wiki/saving-data-into-r-data-format-rds-and-rdata</a></p>
  
  <p>So, I just did <code>save()</code> (and then, to load back - <code>load()</code>) and the <code>rownames</code> are maintained like I wanted it to be. So, storing it now as <code>.RData</code> file.</p>
  